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o Journal of Organometallic Chemistry 777 (2015) 71e 80

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Journal of Organometallic Chemistry

journal homepage: www . elsevier . com/locate/jorganchem

Organotin(IV) hypervalent pseudohalides. Synthesis and structural characterization

Cristina Coza a, 1, Adina Stegarescu b, 1, Razvan_ S uteu a, Anca Silvestru a, *

a Centre of Supramolecular Organic and Organometallic Chemistry, Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babes -Bolyai University, Str. Arany Janos 11, RO-400028 Cluj-Napoca, Romania b National Institute for Research and Development of Isotopic and Molecular Technologies, Str. Donat 67-103, RO-400293 Cluj-Napoca, Romania

a r t i c l e i n f o

Article history:

Received 29 September 2014 Received in revised form

21 November 2014 Accepted 24 November 2014

Available online 4 December 2014

Keywords:

Organotin(IV) pseudohalides NMR spectroscopy

Single crystal X-ray diffraction

a b s t r a c t

Tri- and diorganotin(IV) pseudohalides of type [2-(Me2NCH2)C6H4]R2Sn(NCE) [E S, R Me (1); E Se, R Me (2), Ph (3)] and respectively [2-(Me2NCH2)C6H4]RSn(NCE)2 [E S, R nBu (4), Ph (5), 2-(Me2NCH2)C6H4 (6); E Se; R 2-(Me2NCH2)C6H4 (7)] were obtained by reacting the appropriate organotin(IV) chlorides and alkali metal pseudohalides in stoichiometric amounts. The new species were characterized by multinuclear NMR (1H, 13C, 119Sn and 77Se where appropriate), IR spectroscopy and mass spectrometry. Both the 119Sn NMR and the X-ray diffraction studies evidenced the formation of SneNCE bonds in these compounds. For compounds 1e4, 6 and 7 the single-crystal X-ray diffraction studies revealed intramolecular Me2N/Sn interactions and the formation of hypervalent species 10-Sn-5 in compounds 1e3 and 12-Sn-6 in 4, 6 and 7, respectively. Compounds 1e3 are monomeric species, with monodentate isochalcogenocyanato ligands, while in 4 one of the NCE_ ligands behave as a bridging moiety, thus resulting in dimeric associations. Short p CHg-CH2/Cg and respectively Cg/Cg intermo-lecular contacts resulted in polymeric chains of dimmers in 4 and 3D supramolecular networks in 6 and 7, respectively. The reactions of [2-(Me2NCH2)C6H4]RSnCl2 and MECN in an 1:1 molar ratio resulted in the formation of a mixture of [2-(Me2NCH2)C6H4]RSnCl2, [2-(Me2NCH2)C6H4]RSn(NCE)2 and [2-(Me2NCH2) C6H4]RSnCl(NCE) [E S, R Ph (8), 2-(Me2NCH2)C6H 4 (9); E Se, R 2-(Me2NCH2)C6H 4 (10)]. 2014 Elsevier B.V. All rights reserved.

Introduction

The chemistry of organotin compounds bearing organic groups with one or two pendant arms capable for N/Sn intramolecular coordination, mainly 2-(Me2NCH2)C6H4 and 2,6-(Me2NCH2)C6H3, started to attract a continuously increased interest once the first representatives were reported by van Koten in the second half of the 1970s decade [1,2]. Their structural features and the high thermal and hydrolytic stability determined by the C,N chelating behavior of these ligands make them promising reagents for various applications in biology, catalysis or nanomaterials. The organotin(II) isolated species are practically limited to [2-(Me2NCH2)C6H4]2Sn [3] and [2,6-(Me2NCH2)C6H3]SnCl [4]. Such compounds were extensively used in order to obtain hetero di- or trinuclear species with SneM bonds (M Pd, Pt, Rh, Co, Ru, Zr, W,

Corresponding author.

E-mail address: [email protected] (A. Silvestru).

1 These co-authors have contributed in equal proportions to this work.

http://dx.doi.org/10.1016/j.jorganchem.2014.11.026 0022-328X/ 2014 Elsevier B.V. All rights reserved.

Mo) [5e 13], as well as the distannyne [{2,6-(Me2NCH2)C6H3}Sn]2 [14]. The tin(IV) hypervalent compounds with such groups attrac-ted much more interest, due to the various structural aspects which may arise by varying the number of organic groups with pendant arms, as well as the type of additional anionic ligands in the coor-dination sphere of tin(IV). Among them, the organotin(IV) halides of type [2-(R2NCH2)C6H4]R0SnX2 (R Me, Et; R0 Me, nBu; Ph, 2-(R2NCH2)C6H4; X F, Cl, Br, I) [15e 23] and [2-(Me2NCH2) C6H4]nR3_nSnX (R Me, Ph, n 1, 2; X F, Cl, Br, I) [1,15,16,23e 28], as well as [2-(Me2NCH2)C6H4]SnX3 (X Cl, Br, I) [29,30] were systematically investigated and in all cases the solid-state structure revealed increased coordination numbers at the metal center as a consequence of the strong N/Sn intramolecular interactions. The single-crystal X-ray diffraction studies upon the di- and tri-organotin halides revealed short intermolecular X/H contacts resulting in chain polymers or supramolecular assemblies in most of the species containing such organic groups.

On the other hand, the ambidentate ligands SCN_ and SeCN_ may act either as monodentate (chalcogenocyanato or iso-chalcogenocyanato) or as bidentate, bridging moieties towards

[2-(Me2NCH2)C6H4]RSnCl272C. Coza et al. / Journal of Organometallic Chemistry 777 (2015) 71e80

metals [31]. The single-crystal X-ray diffraction studies upon several diorgano- and triorganotin(IV) pseudohalides have shown a monodentate behavior in complexes containing sterically demanding organic groups, i.e. (2-CH3C6H4)3SnNCS, (2-CH3OC6H4)3SnNCS [32], [(PhMe2Si)3C]Me2SnNCS [33], while poly-meric chains with bridging NCS_ ligands are formed in species as Me2Sn(NCS)2 [34], Me3SnNCS [35], Ph3SnNCS [36], (4-CH3C6H4)3SnNCS [32]. In order to avoid polymerization and to investigate the adaptability and the preference of tin for different coordination geometries, several triorganotin(IV) complexes with additional neutral ligands, besides NCS_, were studied [37e 40]. Only one isoselenocyanato compound was described so far, namely Ph3Sn(NCSe) [41] and several 1:1 adducts with O- or N-donor neutral ligands derived from it [42].

It was observed that organotin(IV) pseudohalides have an increased biological activity, mainly as pesticides [32], in compar-ison with the halides or compounds with other type of ligands. In the same time such species containing both chalcogen (sulfur or selenium) and tin in the same molecule might be of interest to design promising precursors for nanomaterials based on tin chal-cogenides. Due to the high affinity of tin for nitrogen, organotin pseudohalides might be versatile spacers in coordination polymers with transition metals with affinity for the soft chalcogen (S, Se).

Recently we reported several organopnicogen(III) pseudoha-lides of type [2-(Me2NCH2)C6H4]nMX3_n [M Sb, Bi; X NCO, NCS, SeCN; n 1, 2] [43].

A quick search of the Cambridge CSD database revealed no structure of pseudohalides (NCS_ or NCSe_) of tin(IV) species containing organic groups with pendant arms as those mentioned above. As a continuation of our studies, we report here about the synthesis and spectroscopic characterization of several hypervalent triorganotin(IV) compounds of type [2-(Me2NCH2)C6H4]R2Sn(NCE) (R Me, Ph; E S, Se), as well as diorganotin(IV) pseudohalides of

type [2-(Me2NCH2)C6H4]RSn(NCE)2 [R nBu, Ph, 2-(Me2NCH2) C6H4; E S or Se]. The species [2-(Me2NCH2)C6H4]RSnCl(NCE) [R Ph, 2-(Me2NCH2)C6H4; E S or Se] could not be isolated, but they were evidenced by NMR spectroscopy.

Results and discussion

Preparation

New triorganotin(IV) pseudohalides of type [2-(Me2NCH2)C6H4] R2Sn(NCE) [R Me, E S (1), Se (2); R Ph, E Se (3)] were ob-tained according to Scheme 1, by reacting a benzene solution of the appropriate triorganotin chloride with an aqueous solution of KSCN or KSeCN. The reactions were performed by using a 1:1 molar ratio of the respective reactants. Previously we prepared organo-pnicogen pseudohalides of type [2-(Me2NCH2)C6H4]MX2 or [2-(Me2NCH2)C6H4]2MX (M Sb, Bi; X NCO, NCS or SeCN) by using a similar protocol and either benzene or dichloromethane as organic phase [43]. Applying a two phase system (CH2Cl2/water) and stoi-chiometric amounts of the appropriate reactants in order to pre-pare diorganotin pseudohalides of type [2-(Me2NCH2)C6H4] RSn(NCE)2 or [2-(Me2NCH2)C6H4]RSnCl(NCE) [R nBu; Ph, 2-(Me2NCH2)C6H4; E S, Se] we obtained in all cases mixtures of [2-(Me2NCH2)C6H4]RSn(NCE)2, [2-(Me2NCH2)C6H4]RSnCl(NCE) and

( Scheme 1). Moreover, the iso-

selenocyanato derivatives have shown further decomposition in solution.

We succeeded to isolate the desired [2-(Me2NCH2)C6H4] RSn(NCE)2 [E S, R nBu (4), Ph (5), 2-(Me2NCH2)C6H4 (6); E Se, R 2-(Me2NCH2)C6H4 (7)] by using methanol instead of water as solvent for NH4SCN or KSeCN. Compound 6 was obtained also in pure form by using the two phase system (CH2Cl2/water) and a large excess of NH4SCN.

Scheme 1.

C. Coza et al. / Journal of Organometallic Chemistry 777 (2015) 71e8073

Compounds 1e4, 6 and 7 are microcrystalline, colorless solids, soluble in common organic solvents. Compound 5 was obtained as a sticky material and our efforts to obtain it as a solid product failed.

The species of type [2-(Me2NCH2)C6H4]RSnCl(NCE) [E S, R Ph (8), 2-(Me2NCH2)C6H4 (9); E Se, R 2-(Me2NCH2)C6H4 (10)] were only spectroscopically identified in the obtained mixture of products. Single crystals of 10 resulted serendipitously by slow evaporation of CD2Cl2 from the NMR tube solution containing the crude product formed of 7, 10 and [2-(Me2NCH2)C6H4]2SnCl2. Due to the equilibrium process discussed below and, in case of the se-lenium containing species due also to further decomposition, the attempts to separate the compounds by chromatography were unsuccessful.

Spectroscopy

The 1H and 13C NMR spectra of compounds 1e7 suggest the presence of only one species in solution. For the compounds 1e5, containing only one 2-(Me2NCH2)C6H4 group, the aliphatic protons in the Me2NCH2 pendant arm show in the 1H NMR spectra narrow singlet resonances for the methyl and the methylene protons, respectively, thus suggesting that the nitrogen atom in the pendant arm either is not involved in any intramolecular N/Sn coordina-tion or it takes part at ambient temperature to a process comprising decoordination, inversion to nitrogen and recoordination to tin, too fast to be observed at the NMR time scale [44]. In the aromatic region the 1H NMR spectra of these groups show the expected multiplet resonances with a multiplicity determined by the pro-toneproton couplings. The other organic groups, e.g. Me, nBu, Ph, attached directly to tin, give the expected resonances in the aliphatic (Me, nBu) or the aromatic (Ph) region. The resonances of the SnCH3 protons in 1 and 2, as well as the H6 resonance in the 2-

(Me2NCH2)C6H4 groups (see Scheme 2) are accompanied by tin e proton satellites determined by the 117/119Sne1H couplings. In case

of compounds 6 and 7 the two organic groups attached to metal appear to be equivalent in solution. In the aliphatic region two singlet resonances are present, corresponding to the N(CH3)2 pro-tons, while the CH2N protons appear as an AB spin system centered at d 3.75 ppm (dA 3.62 and dB 3.87 ppm) in 6 and at 3.79 ppm (dA 3.67 and dB 3.91 ppm) in 7, respectively, thus suggesting that both 2-(Me2NCH2)C6H4 groups act as C,N-chelating ligands. This solution behavior is similar to that one observed for the starting [2-(Me2NCH2)C6H4]2SnCl2 [15,23]. The VT 1H NMR experiments (in CDCl3) in case of compound 6 revealed a coalescence temperature of 326 K (DGz 15.54 kcal/mol) for the dynamic processes suffered by the N(CH3)2 protons and of 333 K (DGz 16.14 kcal/mol), for the CH2N protons respectively (see Supplementary information, Fig. S1).

The 13C NMR spectra are also in accordance with the expected structures. The resonances of the CH2N carbon atoms, as well as the aliphatic carbons directly bonded to tin are accompanied by tinecarbon satellites. In case of compounds 6 and 7 the three sharp resonances in the aliphatic region, one of them assigned to the CH2N and the other two to the N(CH3)2 carbons confirm the

Scheme 2.

equivalence of the two 2-(Me2NCH2)C6H4 groups presenting intramolecular N/Sn coordination and the non-equivalence of the two Me groups in each pendant arm. The 13C NCS resonances appear in all compounds around 140 ppm, similarly with the chemical shift of the NCS carbon in [2,6-(Me2N)2C6H3]2Sn(NCS) 2 (d 143.4 ppm [45]).

The 119Sn NMR spectra of the compounds containing three organic groups attached to tin show broad resonances in case of compounds 2 and 3, while for 1 the resonance appears as a triplet, as expected due to coupling with nitrogen (d _95.85 ppm, 1JNSn 139.4 Hz), thus suggesting that the NCS ligand is attached by ni-trogen to tin, as it was observed also for other tin complexes with pseudohalides [32,33]. For the species containing two NCE ligands, the 119Sn NMR resonances appear at higher field, broad in case of compounds 4, 5 and 7 and as a quintet in case of compound 6 ( Table 1).

For the products isolated from the reactions between [2-(Me2NCH2)C6H4]RSnCl2 and MECN [R nBu, Ph, 2-(Me2NCH2)C6H4; M NH4, K; E S, Se] performed in an 1:2 molar ratio, using a mixture of water and organic solvent (dichloromethane or ben-zene), in the 119Sn NMR spectra three broad resonances were observed. In case of the products resulted in the reaction between [2-(Me2NCH2)C6H4]2SnCl2 and NH4SCN in an 1:2 molar ratio the singlet resonance at _257.7 ppm was assigned to the starting ma-terial by comparison with the 119Sn NMR resonance for a pure sample of [2-(Me2NCH2)C6H4]2SnCl2, the triplet at d _330.0 ppm (1JNSn 146.2 Hz) to [2-(Me2NCH2)C6H4] 2SnCl(NCS) (9) and the quintet resonance at high field (d _398.4 ppm, 1JNSn 147.1 Hz) to the desired [2-(Me2NCH2)C6H4]2Sn(NCS)2 (6), taking in account that

the multiplet aspect of the latest two resonances is a consequence of the 1J(14Ne119Sn) couplings in these compounds. In this way we

assigned the three resonances observed in case of the other re-actions to the corresponding starting diorganotin(IV) dichloride and the species [2-(Me2NCH2)C6H4]RSnCl(NCE) and [2-(Me2NCH2) C6H4]RSn(NCE)2 (see Table 1). By replacing water with methanol, the reactions of [2-(Me2NCH2)C6H4]RSnCl2 with two equivalents of MECN resulted in the formation of only the desired products 4e7. The reaction proceeds also cleanly with the formation of compound 6 when NH4SCN in aqueous phase was used in excess (1:4 molar ratio).

Table 1

119Sn NMR data for the starting organotin(IV) halides and the compounds 1e10.

Compound119Sn NMR (d, ppm)77Se NMR Ref.

(d, ppm)

[2-(Me2NCH2)C6H4]2SnCl2_257.7 (CD2Cl2) [15]

n_252.84 (CDCl3) [17]

[2-(Me2NCH2)C6H4] BuSnCl2_103.0 (CDCl3)

[2-(Me2NCH2)C6H4]PhSnCl2_170.0 (CDCl3) [15]

[2-(Me2NCH2)C6H4]Me2SnCl_48.7 (CH2Cl2/ [23]

acetone-d6)

[2-(Me2NCH2)C6H4]Ph2SnCl_176.9 (CDCl3) [26]

[2-(Me2NCH2)C6H4]2PhSnCl_185.7 (CDCl3) [15]

[2-(Me2NCH2)C6H4]Me2Sn(NCS) (1)_195.85t (CDCl3,

JSnN 139.4 Hz)_346.8

[2-(Me2NCH2)C6H4]Me2Sn(NCSe) (2)_87.89s, br. (CDCl3)

[2-(Me2NCH2)C6H4]Ph Sn(NCSe) (3)_224.5s, br. (CDCl3)343.2

n 2_

[2-(Me2NCH2)C6H4] BuSn(NCS)2 (4)_266.6s, br. (CDCl3)

[2-(Me2NCH2)C6H4]PhSn(NCS)2 (5)_329.3s, br. (C6D6)

[2-(Me2NCH2)C6H4]2Sn(NCS)2 (6)_327.6s, br. (CD2Cl2)

_1398.4qu (CD2Cl2,

JNSn 147.1 Hz)_350.3

[2-(Me2NCH2)C6H4]2Sn(NCSe)2 (7)_406.4s, br. (CDCl3)

[2-(Me2NCH2)C6H4]PhSnCl(NCS) (8)_242.6s, br. (CDCl3)

[2-(Me2NCH2)C6H4]2SnCl(NCS) (9)_249.1s, br. (CD2Cl2)

_1330.0t (CD2Cl2,

JNSn 146.2 Hz)_346.6

[2-(Me2NCH2)C6H4]2SnCl(NCSe) (10)_329.5s, br. (CDCl3)

74C. Coza et al. / Journal of Organometallic Chemistry 777 (2015) 71e80

Table 2

Selected interatomicdistances () andangles (_ ) in compounds[2-(Me2NCH2)C6H4]Me2Sn(NCS) (1),[2-(Me2NCH2)C6H4]Me2Sn(NCSe) (2) and[2-(Me2NCH2)C6H4]

Ph2Sn(NCSe) (3).

123a3b

C1eSn12.123(4)C1eSn12.118(7)C1eSn12.136(5)C23eSn22.131(5)



N1eSn12.456(4)N1eSn12.432(7)N1eSn12.453(4)N3eSn22.438(4)


C12eN21.158(6)C12eN21.112(11)C22eN21.140(7)C44eN41.141(6)

C12eS11.595(6)C12eSe11.787(9)C22eSe11.768(6)C44eSe21.783(5)

C10eSn1eC11117.1(2)C10eSn1eC11116.7(4)C16eSn1eC10122.59(19)C32eSn2eC38114.4(2)



C10eSn1eN290.3(2)C10eSn1eN294.5(3)C16eSn1eN293.34(19)C32eSn2eN495.37(19)






N2eSn1eN1165.96(15)N2eSn1eN1165.7(3)N2eSn1eN1170.99(16)N4eSn2eN3166.89(17)

N2eC12eS1179.8(6)N2eC12eSe1179.0(9)N2eC22eSe1179.2(5)N4eC44eSe2179.0(5)

C12eN2eSn1149.3(4)C12eN2eSn1148.1(7)C22eN2eSn1157.2(4)C44eN4eSn2169.3(5)

When the reactions between [2-(Me2NCH2)C6H4]RSnCl2 [R Ph or 2-(Me2NCH2)C 6H4] and NH4SCN were performed in a 1:1 molar ratio, in a mixture of water and organic solvent (dichloromethane or benzene), we obtained again a mixture of the three species. In order to further investigate the process leading to this result we performed directly in an NMR tube, using either CD2Cl2 or C6D 6 as solvent, the reaction between [2-(Me2NCH2)C 6H4]2SnCl2 and [2-(Me2NCH2)C6H4]2Sn(NCS)2 in an 1:1 molar ratio. The 1H NMR spectrum of this mixture revealed the instantaneously formation of a mixture of the starting ma-terials and [2-(Me2NCH2)C6H4] 2SnCl(NCS) (9), according to the equilibrium depicted in Equation (1) (see Supplementary information, Figs. S2a, S2b and S3):

spectra show besides the peaks corresponding to the [{2-(Me2NCH2)C6H4}RSn(NCE)] cation, peaks corresponding to the species [{2-(Me2NCH2)C6H4}RSnCl] [R 2-(Me2NCH2)C6H4, nBu, Ph]. This behavior might suggest the formation of a mixture of the starting diorganotin(IV) dichloride and mono- and di-isothiocyanato diorganotin(IV) complexes.

The infrared spectra of compounds 1e7 show very strong bands characteristic for the n(CN) stretching vibration of the NCE group, in the region 2040e2070 cm_1 for the species with monodentate NCE_ ligands and at 2104 cm_1 in case of com-pound 4, with bridging NCS_ groups, in agreement with the previously reported values for other related compounds [40,46].

2 _ Me2NCH2C6H4&2SnNCS2 2 _ Me2NCH2C6H4&2SnCl2#2 2 _ Me2NCH2C6H4&2SnCl NCS(1)

As expected, the two organic groups in 9 are no more equivalent, and this results in two AB systems for the CH2N protons. The same consideration applies for 10, but in this case the dA and dB values corresponding to the respective two AB systems are overlapped and they could not be unambiguously assigned.

From the data given in Table 1 it can be observed that the 119Sn NMR d values are decreasing as [2-(Me2NCH2)C 6H4]

BuSn(NCS)2 > [2-(Me2NCH2)C6H4]PhSn(NCS)2 > [2-(Me2NCH2) C6H4]2Sn(NCS)2 and respectively [2-(Me2NCH2)C6H4]RSn-Cl2 > [2-(Me2NCH2)C6H4]RSnCl(NCS) > [2-(Me2NCH2)C6H4] RSn(NCS)2.

In the compounds containing NCSe_ ligands, the 77Se NMR spectra present one singlet resonance in each case (see Table 1).

The APCI mass spectra of the triorganotin(IV) complexes 1e3 show peaks of 100% intensity corresponding to the cations [{2-(Me2NCH2)C6H4}R2Sn] (R Me, Ph). For compounds 4e7 the APCI mass spectra show peaks corresponding to the [{2-(Me2NCH2)C6H4}RSn(NCE)] cation. The base peaks in the ESI-MS spectra for compounds 5e7 correspond to the anions [{2-(Me2NCH2)C6H4}RSn(NCE)3]_. For the products isolated from the reactions performed in order to obtain diorganotin(IV) complexes using stoichiometric amounts of reactants and a two phase water/organic solvent system, the APCI mass

Single-crystal X-ray diffraction studies

Single crystals of 1e4, 6 and 7 suitable for X-ray diffraction studies were obtained from a CH2Cl2/n-hexane mixture (1/5, v/v) at room temperature, while single crystals of 10 resulted serendipi-tously from the CD2Cl2 solution containing a mixture of 7, 10 and [2-(Me2NCH2)C6H4]2SnCl2, formed in the reaction between [2-(Me2NCH2)C6H4]2SnCl2 and KSeCN (CH2Cl2/water mixture of solvents).

Crystal and molecular structure of [2-(Me2NCH2)C6H4]Me2Sn(NCS) (1), [2-(Me2NCH2)C6H 4]Me2Sn(NCSe) (2) and [2-(Me2NCH2)C6H4] Ph2Sn(NCSe) (3)

Selected bond lengths and angles for compounds 1e3 are given in Table 2. The three structures are similar, with the observation that the crystal of compound 3 contains two independent mole-cules. The ORTEP-like diagram of compound 1 is depicted in Fig. 1, while the other two molecular structures are presented in the Supplementary material (see Supplementary information, Figs. S4 and S5).

The three compounds are monomeric in solid state, with pen-tacoordinated tin atoms. The nitrogen atom of the pendant arm is involved in strong intramolecular interactions with tin, while the


Fig. 1. ORTEP-like representation at 30% probability and atom numbering scheme for the pRN1-1 isomer (hydrogen atoms are omitted for clarity).

pseudohalide ligand acts as monodentate isochalcogenocyanato moiety, similarly with the situation found in other organotin(IV) complexes with pseudo-halides [32,33]. In this way 10-Sn-5 hypervalent species [47] with a distorted trans-C3SnN2 trigonal bipyramidal coordination are formed [NeSneN 165.96(15)_ in 1, 165.70(3)_ in 2, 170.99(16)_ in 3a and 166.89(17)_ in 3b]. The Me2N/Sn interactions are slightly greater than the SneNCE (E S, Se) bonds {Me2N/Sn/SneNCE 2.456(4)/2.227(5) in 1, 2.432(7)/ 2.305(8) in 2, 2.453(4)/2.221(5) in 3a and 2.438(4)/2.247(5) in 3b, respectively, vs. rvdW (Sn,N) 3.75 , rcov (Sn,N) 2.15 [48]} and close to the values found in the starting triorganotin chlorides [23]. The SneNCE distances are in agreement with the covalent nature of the metaleligand interaction. The NCE ligand is almost linear [NeCeE 179.8(6)_ in 1, 179.0(9)_ in 2, 179.2(5)_ in 3a and 179.0(5)_ in 3b], but the molecules are bent at nitrogen, with SneNeCE an-gles of 149.3(4)_ in 1, 148.1(7)_ in 2, 157.2(4)_ in 3a and 169.3(5)_ in 3b, probably due to a steric effect. The NeCE interatomic distances of 1.158(6) in 1, 1.112(11) in 2, 1.140(7) in 3a and 1.141(6) in 3b are similar with the values found in other related compounds [35,38]. The NCeE distances (see Table 2) are consistent with a sp carbon atom { rcov(Csp,S) 1.64, rcov(Csp,Se) 1.77 [48]}.

The five membered SnC3N chelate rings are folded along the Sn/Cmethylene axis and the nitrogen atoms are displayed out of the best SnC3 plane at a distance of 0.78 in 1, 0.76 in 2, 0.73 in 3a and 0.77 in 3b, respectively. The intramolecular N/Sn interac-tion induces planar chirality. Compounds 1 and 2 crystallize in the chiral orthorhombic space group P2(1)2(1)2(1) and therefore the crystals contain only the pRN1 isomer, while compound 3 crystal-lizes in the monoclinic P2(1)/n space group as an 1:1:1:1 mixture of pRN1-3a, pSN1-3a, pRN3-3b and pSN3-3b isomers [49].

Crystal and molecular structure of [2-(Me2NCH2)C6H4]BuSn(NCS)2 (4), [2-(Me2NCH2)C6H4]2Sn(NCS)2 (6) and [2-(Me2NCH2) C6H 4]2Sn(NCSe)2 (7)

Selected interatomic distances and angles for compounds 4, 6 and 7 are presented in Table 3. The ORTEP-like diagrams of com-pounds 4 and 7 are depicted in Figs. 2 and 3, respectively. The structure of compound 6 is similar with that one of 7 and it is given in Supplementary information, Fig. S6.

In all three species the nitrogen atoms in the pendant arms of the 2-(Me2NCH2)C6H4 groups are coordinated to tin, thus deter-mining the formation of one (in 4) and respectively two (in 6 and 7) five-membered SnNC3 chelate rings folded about the imaginary Sn/CH2N axis, with the nitrogen atoms displayed out of the best

SnC3 plane at 0.70 in 4, 0.69 and 0.66 in 6, and 0.65 and 0.66 in 7, respectively. The NCS_ ligands are monodentate in compounds 6 and 7, while in compound 4 one of the NCS_ ligand acts as a bridging moiety {Sn1/S20 3.546(2) vs. rvdW (Sn,S) 4.05 [48]}, thus giving rise to dimeric associations ( Fig. 2). In this way 12-Sn-6 hypervalent species [47] with a distorted octahedral geometry is realized about tin in all three compounds. In compounds 6 and 7 each nitrogen in the pendant arm is trans to one NCS nitrogen [N1eSn1eN4 164.70(12)_ and N2eSn1eN3 168.67(11)_ in 6 and N1eSn1eN3 168.99(15)_ and N2eSn1eN4 163.74(15)_ in 7], while in compound 4 one NCS nitrogen is trans to the nitrogen in the pendant arm [N1eSn1eN3 169.21(15)_] and the other is trans to one SCN sulfur atom in the neighbor molecule [N2eSn1eS20 174.26(11)_]. In all three compounds the N/Sn intramolecular coordination, besides the planar chirality (pRN and pSN isomers due to the non-planar SnC3N chelate ring), results in chirality induced at the metal atom. Therefore, the bis(C,N-chelate) species 6 and 7 crystallize as 1:1 mixtures of DSn,pRN1,pSN2 and LSn,pSN1,pRN2 iso-mers, and LSn,pR N1,pSN2 and DSn,pSN1,pRN2 isomers, respectively, while compound 4 crystallizes as a racemic of CSn,pSN1 and ASn,pRN1 isomers [49]. Pairs of CSn,pSN1 and ASn,pRN1 isomers are associated in dimeric units which are further connected in a chain polymer by p intermolecular contacts established between a g-CH2 hydrogen in each nBu group and the C6H4 rings of the neighbor dimmers [H12A/Cg(C100 eC600 ) 2.78 ] ( Fig. S7, Supplementary information). We have to mention that the starting dichlorides are polymers, i.e. a layered structure built by intermolecular Cl/H40 interactions in [2-(Me2NCH2)C6H4]2SnCl2 [23] and a polymeric chain built by Sn/Cl0 in [2-(Me2NCH2)C6H4]nBuSnCl2 [17]. The Sn2(NCS)2 eight-membered ring in the dimeric units has a chair conformation with the tin atoms in apices. The other two monodentate NCS_ li-gands, as well as the nBu and the 2-(Me2NCH2)C6H4 groups are trans each other, with respect to the N2C2S2 plane in the eight-membered ring. The NCS_ ligands have a linear arrangement and, similarly with the situation described for compounds 1e3 the SneN]C]S systems are bent at nitrogen (see Table 3). In compounds 6 and 7 the C6H4 rings of both C,N-ligands are involved in p Cg/Cg in-teractions with the C6H4 rings of the neighbor molecules (range 4.67e5.37 in 6 and 4.74e5.38 in 7), thus determining a su-pramolecular 3D network ( Supplementary information, Fig. S8).

Crystal and molecular structure of [2-(Me2NCH2)C6H4]2SnCl(NCSe) (10)

The ORTEP-like diagram for 10 is represented in Fig. 4 and important bond lengths and angles are given in Table 3.

In compound 10 both 2-(Me2NCH2)C6H4 groups act also as C,N-chelating ligands, with the nitrogen atom of one of the pendant arms in trans position to the NCS_ ligand [N2eSn1eN3 169.3(2)_], while the nitrogen in the other pendant arm is trans to the chlorine atom [N1eSn1eCl1 164.43(16)_], thus determining a distorted octahedral environment about tin. The carbon atoms of the ligand containing N2 were found to be disordered over two positions, corresponding with equal occupancy to the RN2 and the SN2 iso-mers. The carbon atoms labeled with A correspond to the isomer RN2. The SnC3N five-membered chelate rings are folded about the Sn/Cmethylene axis, with the nitrogen atoms deviated from the respective SnC3 plane (N1 is deviated at 0.71 from the Sn1/C1/C2/ C7 plane, while N2 is deviated at 0.71 from the Sn1/C10/C11/C16 plane and at 0.67 from the Sn1/C10A/C11A/C16A plane). Similarly with the situation described for compounds 6 and 7, the two N/Sn intramolecular interactions determine the formation of an 1:1 mixture of LSn,pSN1,pSN2 and DSn,pRN1,pR N2 isomers in the crystal of 10. Short p Cg/Cg intermolecular interactions results in a 2D su-pramolecular network ( Supplementary information, Fig. S9).


Table 3

Selected interatomic distances () and angles (_ ) in compounds [2-(Me2NCH2)C6H4]nBuSn(NCS)2 (4), [2-(Me2NCH2)C6H4]2Sn(NCS)2 (6), [2-(Me2NCH2)C6H4]2Sn(NCSe)2 (7) and [2-(Me2NCH2)C6H4]2SnCl(NCSe) (10).

46710



N1eSn12.387(4)N1eSn12.500(3)N1eSn12.517(4)Cl1eSn12.432(3)



C14eN21.121(6)N4eSn12.144(4)N4eSn12.169(4)N3eSn12.214(8)

C14eS11.618(6)C19eN31.144(5)C19eN31.135(6)C19eN31.040(12)

C15eN31.158(6C19eS11.611(4)C19eSe11.769(5)C19eSe11.805(9)

C15eS21.603(5)C20eN41.148(5)C20eN41.116(6)C10AeSn12.13(6)

Sn1eS20 a3.546(2)C20eS21.603(5)C20eSe21.781(6)





C1eSn1eN498.43(15)C1eSn1eN4100.92(18)C1eSn1eCl198.1(2)

C10eSn1eN188.45(11)C10eSn1eN190.56(15)C10eSn1eN191.7(16)



C10eSn1eN395.0(2)C10eSn1eN4101.76(15)C10eSn1eN498.15(18)C10eSn1eCl198.7(16)

C10AeSn1eC1153.8(15)

N1eSn1eN2106.25(9)N1eSn1eN2106.97(13)C10AeSn1eN187.4(16)

N1eSn1eN286.46(15)N1eSn1eN381.35(11)N1eSn1eN3168.99(15)C10AeSn1eN274.2(17)

N1eSn1eN3169.21(15)N4eSn1eN386.02(15)N4eSn1eN385.15(18)C10AeSn1eN397.4(16)

N2eSn1eN388.81(17)N1eSn1eN4164.70(12)N1eSn1eN488.01(15)C10AeSn1eCl1103.7(16)

N2eSn1eN3168.67(11)N2eSn1eN380.93(15)Cl1eSn1eN387.6(2)

N2eSn1eN487.58(12)N2eSn1eN4163.74(15)N1eSn1eN2105.7(2)

C14eN2eSn1140.8(4)N1eSn1eN380.2(2)

C15eN3eSn1160.4(4)N3eC19eS1178.8(4)N3eC19eSe1178.6(5)N2eSn1eN3169.2(2)

N4eC20eS2178.1(4)N4eC20eSe2177.6(5)Cl1eSn1eN1164.44(17)

Cl1eSn1eN288.01(16)

N2eC14eS1178.1(5)C19eN3eSn1166.7(4)C19eN3eSn1167.9(4)C19eN3eSn1168.6(8)

N3eC15eS2178.1(4)C20eN4eSn1146.9(4)C20eN4eSn1147.7(5)N3eC19eSe1178.2(9)

a Symmetry equivalent position (1 _ x, 2 _ y, 2 _ z) is given by prime.

Conclusions

Our studies focused on several displacement reactions between tri- and respectively diorganotin(IV) chlorides and alkali metal pseudohalides revealed in all cases the formation of hypervalent

species with strong intramolecular N/Sn interactions. Both the solution NMR studies and the solid state structures have shown the formation of SneNCE bonds. The single-crystal X-ray diffraction studies put in evidence monomeric structures and a monodentate behavior of the NCE_ ligands for compounds 1e3 (10-Sn-5 hyper-valent species, with a distorted trigonal bipyramidal coordination geometry). Compounds 6, 7 and 10 can be described as 12-Sn-6

Fig. 2. Dimeric association of CSn,pSN1 and ASn,pRN1 isomers in the crystal of 4, based on SneNCS/Sn0 intermolecular interactions (hydrogen atoms are omitted for clarity) [symmetry equivalent atoms (1 _ x, 2 _ y, 2 _ z), are given by prime].

Fig. 3. ORTEP-like representation at 30% probability and atom numbering scheme for the LSn,pRN1,pSN20 -7 isomer (hydrogen atoms are omitted for clarity).


Fig. 4. ORTEP-like representation at 50% probability and atom numbering scheme for LSn,pSN1,pSN200 -10 isomer (hydrogen atoms are omitted for clarity).

hypervalent species, with a distorted octahedral coordination ge-ometry. Short p Cg/Cg intermolecular interactions result in 3D supramolecular networks in 6 and 7, and a layer structure in 10, respectively. In case of compound 4 the NCS_ ligand acts as a bidentate, bridging moiety, thus giving rise to dimeric associations with hexacoordinated tin atoms. Due to the weak Sn/S intermo-lecular interaction 4 can be described as a 12-Sn-6 hypervalent species as well. Short p CHg-CH2/Cg intermolecular interactions determine the formation of a polymeric chain in 4. The reactions between [2-(Me2NCH2)C6H4]RSnCl2 and alkali metal pseudohalides either in 1:1 or 1:2 molar ratio in a two phase CH2Cl2/water system lead to mixtures of [2-(Me2NCH2)C6H4]RSn(NCE)2, [2-(Me2NCH2) C6H4]RSnCl(NCE) and [2-(Me2NCH2)C6H4]RSnCl2, due to the redis-tribution reaction suffered by the [2-(Me2NCH2)C6H4]RSnCl(NCE) species once formed. We could not obtain or separate in pure form the compounds of type [2-(Me2NCH2)C6H4]RSnCl(NCE), but we evidenced their formation by NMR. The N/Sn intramolecular co-ordination induces planar chirality and chirality to the tin atom, as well. As a consequence, the compounds crystallize as racemic mixtures.

Experimental

Materials and procedures

Starting materials were prepared according to literature pro-cedures: [2-(Me2NCH2)C6H4]RSnCl2 (R [2-(Me2NCH2)C6H4] [21], nBu [17], Ph [16]), [2-(Me2NCH2)C6H4]R2SnCl (R Me, Ph [23]), or were commercially available: NH4SCN, KSCN, KSeCN. Elemental analyses were performed on a Flash EA 1112 analyzer. Melting points were measured on an Electrothermal 9200 apparatus and are not corrected. 1H and 13C NMR spectra were recorded in CDCl3 or CD2Cl2, either on a BRUKER Avance DRX 300 or a BRUKER DRX 400 instrument. The chemical shifts are reported in ppm relative to the residual peak of solvent (ref. CHCl3: 1H 7.26, 13C 77.0 ppm; CH2Cl2: 1H 5.33, 13C 54.24 ppm). 1H and 13C resonances were assigned using 2D NMR experiments (COSY, HSQC and HMBC),

according to the numbering scheme shown in Scheme 2. The 77Se and the 119Sn NMR spectra were obtained on a BRUKER DRX 400

equipment, using diphenyl diselenide and Me4Sn respectively, as external standards. The NMR data were processed using the Mes-tReNova software [50]. Infrared spectra were recorded on a BioRad FTS-165 machine as KBr pellets. APCI and ESI mass spectra were performed on an LTQ Orbitrap e XL instrument.

Synthesis

Preparation of [2-(Me2NCH2)C6H4]Me2Sn(NCS) (1). An aqueous solution of KSCN (0.114 g, 1.17 mmol) in 20 mL water was added to a benzene solution (caution, benzene is carcinogenic!) (20 mL) of [2-(Me2NCH2)C6H4]Me2SnCl (0.373 g, 1.17 mmol) and the reaction mixture was stirred for 10 h at room temperature. The organic layer was separated and the compound was extracted from the water solution with 2 _ 25 mL of CH2Cl2. The organic phase was dried over anhydrous Na2SO4. Then the solvent was removed in vacuum and the solid residue was recrystallized from a CH2Cl 2/n-hexane mixture to give the title compound as a colorless microcrystalline solid. Yield: 0.212 g (53%). M.p. 107 _C. Anal. Found: C, 42.42; H, 5.44; N, 8.28%. Calc. for C12H18N2SSn (Mw 341.04): C, 42.26; H, 5.32; N, 8.21%; FT-IR (cm_1): n(CN) 2065vs, n(CS) 760m, d(NCS) 450w. 1H NMR (CDCl3, 400 MHz) d [ppm]: 0.63 (s, 6H, SnCH3, 2JSnH 67.2 Hz), 2.31 (s, 6H, NCH3), 3.62 (s, 2H, CH2N), 7.14 (m, 1H, C6H4, H3), 7.34 (m, 2H, C6H4, H4,5), 7.97 (m, 1H, C6H4, H6, 3J117/119SnH 69.6/ 70.1 Hz). 13C NMR (CDCl3, 75.46 MHz) d [ppm]: _3.34 (s, SnCH3, 1J117/119SnC 510.6/534.3 Hz), 45.24 (s, NCH3), 64.68 (s, CH2N, 2JSnC 32.1 Hz), 126.64 (s, C6H4, C3, 3JSnC 60.9 Hz), 128.32 (s, C6H4, C5, 3JSnC 66.2 Hz), 129.80 (s, C6H4, C4, 4JSnC 13.4 Hz), 137.04 (s, C6H4, C6, 2JSnC 39.1 Hz), 138.14 (s, br., C6H4, C1), 138.50 (s, C6H4, C2), 141.58 (s, NCS). 119Sn (CDCl3, 111.9 MHz) d [ppm]: _95.85 (t, 1JNSn 139.4 Hz). APCI MS (CH3CN), m/z (%): 284.05 (100) [M _ SCN].Compounds 2 and 3 were prepared similarly:[2-(Me2NCH2)C6H4]Me2Sn(NCSe) (2) from KSeCN (0.148 g, 1.03 mmol) in 20 mL water and [2-(Me2NCH2)C6H4]Me2SnCl (0.328 g, 1.03 mmol) in benzene (20 mL), as a colorless solid. Yield: 0.186 g (46.5%). M.p. 113 _C. Anal. Found: C, 37.28; H, 4.79; N, 7.25%. Calc. for C12H18N2SeSn (Mw 387.94): C, 37.15; H, 4.68; N 7.22%; FT-IR (cm_1): n(CN) 2044vs, n(CSe) 546w, d(NCSe) 424w. 1H NMR (CDCl3, 400 MHz) d [ppm]: 0.67 (s, 6H, SnCH3, 2JSnH, 66.3 Hz), 2.34 (s, 6H, NCH3), 3.65 (s, 2H, CH2N), 7.17 (m, 1H, C6H4, H3), 7.38 (m, 2H, C6H4, H4,5), 8.01 (m, 1H, C6H4, H6, 3J117/119SnH 60.6/73.1 Hz). 13C NMR (CDCl3, 75.46 MHz) d [ppm]: _3.12 (s, SnCH3, 1J117/119SnC 516.6/ 528.3 Hz), 45.38 (s, NCH3), 64.88 (s, CH2N, 3JSnC 32.5 Hz), 126.64 (s, C6H4, C3, 3JSnC 61.2 Hz), 128.69 (s, C6H4, C5, 3JSnC 68.7 Hz), 130.01 (s,

C6H4, C4, 4JSnC 13.6 Hz), 137.25 (s, C6H4, C6, 2JSnC 39.4 Hz), 137.87 (s, br., C6H4, C1), 138.15 (s, C6H4, C2), 141.38 (s, NCSe). 119Sn (CDCl3,

111.9 MHz) d [ppm]: _87.89s, br. 77Se (CDCl3, 76.31 MHz) d [ppm]: _346.83s. APCI MS (CH3CN), m/z (%): 284.05 (100) [M _ SeCN].

[2-(Me2NCH2)C6H4]Ph2Sn(NCSe) (3), from KSeCN (0.140 g, 0.97 mmol) in water (20 mL) and [2-(Me2NCH2)C6H4]Ph2SnCl (0.432 g, 0.97 mmol) in benzene (20 mL), as a colorless solid. Yield: 0.21 g (42%). M.p. 138 _C. Anal. Found: C, 51.72; H, 4.54; N, 5.52%. Calc. for C22H22N2SeSn (Mw 512.08): C, 51.60; H, 4.33; N, 5.47%. FT-IR (cm_1): n(CN) 2055vs, n(CSe) 698m, d(NCSe) 454m. 1H NMR (CDCl3, 400 MHz) d [ppm]: 2.02 (s, 6H, NCH3), 3.61 (s, 2H, CH2N), 7.24 (m, 1H, C6H4, H3), 7.40e7.57 (m, 8H, C6H4, H4,5 C6H5 meta para), 7.66 (m, 4H, C6H5-ortho), 8.29d (1H, C6H4, H6, 3JHH 7.05, 3J117/119SnH 62.4/76.5 Hz). 13C NMR (CDCl3, 100.6 MHz), d [ppm]: 45.99 (s, NCH3), 64.78 (s, CH2N), 127.25 (s, C3), 128.92 (s, C5), 129.24 (s, C 6H5-meta), 130.13s (C6H5-para), 130.64 (s, C4), 135.55

(s, C1), 135.74 (s, C6H5-ortho, 2JSnC 44.8 Hz), 137.89 (s, C6H5-ipso), 138.19 (s, C6), 138.81 (s, C2), 142.17 (NCSe). 119Sn (CDCl3, 111.9 MHz)

d [ppm]: _224.5s, br. 77Se (CDCl3, 76.31 MHz) d [ppm]: _343.2s, br. MS (APCI, CH3CN), m/z (%): 408.08 (100) [M _ SeCN].


Synthesis of [2-(Me2NCH2)C6H4]nBuSn(NCS)2 (4). A solution of KSCN (0.159 g, 1.64 mmol) in 20 mL methanol was added to [2-(Me2NCH2)C6H4]BuSnCl2 (0.313 g, 0.82 mmol) in dichloromethane (15 mL), at room temperature and the reaction mixture was stirred for 2 h. The solvent was removed in vacuum and the remained solid was extracted with CH2Cl2. After removing dichloromethane in vacuum, 4 resulted as a colorless solid. Yield: 0.223 g (64%). M.p. 110 _C. Anal. Found: C 42.34; H 4.88; N 9.91%. Calc. for C15H21N3S2Sn (Mw 426.16): C, 42.28; H, 4.97; N, 9.86%. FT-IR (cm_1): n(CN) 2104vs, n(CS) 760m, d(NCS) 466m. 1H NMR (CDCl3, 300 MHz) d [ppm]: 0.97 (t, 3H, SnCH2CH 2CH2CH3, 3J HH 7.3 Hz), 1.45 (m, 2H, SnCH2CH2CH2CH3), 1.73 (m, 2H, SnCH2CH2CH2CH3), 1.86 (m, 2H,

SnCH2CH2CH2CH3), 2.46 (s, 6H, NCH3), 3.75 (s, 2H, CH2N), 7.23 (m, 1H, C6H4, H3), 7.45 (m, 2H, H4,5), 7.97 (m, 1H, H6, 3JSnH 83.8 Hz). 13C NMR (CDCl3, 75.46 MHz) d [ppm]: 13.65 (s, Cd), 22.92 (s, br., Cg),26.27 (s, C, 1J 109.0 Hz), 27.01 (s, C , 2J45.0 Hz), 45.12 (s,

aSnCbSnC

NCH3), 63.37 (s, CH2N, 3JSnC 37.8 Hz), 127.51 (s, C3, 3JSnC 75.3 Hz),

129.08(s,C5, 3JSnC 87.9 Hz),131.50 (s, C4), 136.55 (s, C6,

2JSnC61.2 Hz),140.86 (s, C2, 2JSnC50.3 Hz),143.1 (s, br., C1NCS).

119

Sn NMR (CDCl3, 111.9 MHz) d [ppm]: _266.6s, br. MS (APCI,

CH3CN), m/z (%): 369.05 (100) [M _ SCN].

Compounds 5e7 were prepared similarly:

[2-(Me2NCH2)C6H4]PhSn(NCS)2(5) fromNH4SCN (0.102 g,

1.34 mmol) in 10 mL methanol and [2-(Me2NCH2)C6H4]PhSnCl2 (0.269 g, 0.67 mmol) in 20 mL dichloromethane, as a colorless sticky material. Yield: 0.211 g (70.5%). Anal. Found: C, 45.84; H, 3.78; N, 9.35%. Calc. C17H17N3S2Sn (Mw 446.15): C, 45.77; H, 3.84; N, 9.42%. FT-IR (cm_1): n(CN) 2067vs, n(CS) 754m, d(NCS) 451m. 1H NMR (CDCl3, 300 MHz) d [ppm]: 2.26 (s, 6H, NCH3), 3.73 (s, 2H, CH2N), 7.28 (m, 1H, C6H4, H3), 7.45e7.54 (m, 5H, C6H4, H4,5 C6H5-meta para), 7.60 (m, 2H, C6H5-ortho) 8.14 (d, br., 1H, C6H4, H6, 3JHH 7.1, 3J117/119SnH 86.7/99.8 Hz). 13C NMR (CD2Cl2, 75.46 MHz) d [ppm]: 45.27 (s, NCH3), 62.92 (s, CH2N, 3JSnC 48.9 Hz), 128.00 (s, C3, 3JSnC 84.2 Hz), 129.13 (s, C5), 129.62 (s, C6H5-meta), 131.03 (s, C6H5-para), 131.96 (s, C4, 4JSnC 16.3 Hz), 134.06 (s, C6H5-ortho, 2JSnC 63.8 Hz),

136.79 (s, C6, 2JSnC 64.3 Hz), 141.38 (s, C6H5-ipso C1), 143.28 (NCS) (C2 could not be assigned). 119Sn (CDCl3, 111.9 MHz):

d [ppm]: _245.3s, br. MS (APCI, CH3CN), m/z (%): 389.01 (100) [M _ NCS]. MS (ESI_, CH3CN), m/z (%): 504.98 (100) [M NCS]_.[2-(Me2NCH2)C6H4]2Sn(NCS)2 (6) from NH4SCN (0.061 g, 0.80 mmol) in 10 mL methanol and [2-(Me2NCH2)C6H4]2SnCl2 (0.182 g, 0.40 mmol) in 20 mL dichloromethane, a colorless solid. Yield: 0.182 g (90.5%). M.p. 248 _C. Anal. Found: C, 47.68; H, 4.84 N, 11.15%. Calc. C20H24N4S2Sn (Mw 503.25): C, 47.73; H, 4.81; N, 11.13%. FT-IR (cm_1): n(CN) 2069vs, n(CS) 754s, d(NCS) 431w. 1H NMR (CD2Cl2, 400 MHz) d [ppm]: 2.09 (s, 6H, NCH3), 2.48 (s, 6H, NCH3), 3.75 (AB spin system with dA 3.62 and dB 3.87 ppm, 4H, CH2N, 2JHH 14.6 Hz), 7.33 (m, 2H, C6H4, H3, 4J117/119SnH 37.20/ 52.84 Hz), 7.56 (m, 4H, C6H4, H4,5), 8.02 (m, 2H, C6H4, H6, 3J117/119SnH 99.7/113.0 Hz). 1H NMR (CDCl3, 400 MHz) d [ppm]: 2.05 (s, 6H, NCH3), 2.44 (s, 6H, NCH3), 3.68 (AB spin system with dA 3.55 and dB 3.82 ppm, 4H, CH2N, 2JHH 14.4 Hz), 7.23 (m, 2H, C6H4, H3, 4J117/119SnH 36.24/50.55 Hz), 7.48 (m, 4H, C6H4, H4,5), 7.99 (d, 2H, C6H4, H6, 3JHH 6.26, 3J117/119SnH 102.1/111.7 Hz). 13C NMR (CDCl3, 100.6 MHz) d [ppm]: 46.16 (s, NCH3), 47.18 (s, NCH3), 63.75 (s, CH2N, 3JSnC 49.9 Hz), 128.14 (s, C3, 3JSnC 19.85 Hz), 128.98 (s, C 5), 131.09 (s, C4,

4JSnC 18.58 Hz), 135.15 (s, C6, 2JSnC 54.3 Hz), 136.46 (s, C2), 140.19 (s, C1, 1JSnC 70.1 Hz), 141.05 (s, br., NCS). 119Sn (CD2Cl2, 149.21 MHz)

d [ppm]: _398.4qu (1JNSn 147.1 Hz). MS (APCI, CH3CN), m/z (%): 446.07 (100) [M _ NCS]. MS (ESI_, CH3CN), m/z (%): 561.34 (100) [M NCS]_.

[2-(Me2NCH2)C6H4]2Sn(NCSe)2 (7) from KSeCN (0.049 g, 0.34 mmol) in methanol and [2-(Me2NCH2)C6H4]2SnCl2 (0.156 g, 0.34 mmol) in dichloromethane, as a colorless solid. Yield: 0.16 g (81%). M.p. 187 _C. Anal. Found: C 39.84; H 4.12; N 9.17%. Calc. for

C20H24N4Se2Sn (Mw 597.05): C, 40.23; H, 4.05; N, 9.38%. FT-IR (cm_1): n(NC) 2059vs, n(CSe) 698m, d(NCSe) 447m. 1H NMR (CD2Cl2, 300 MHz) d [ppm]: 2.13 (s, br., 6H, NCH3), 2.52 (s, br., 6H, NCH3), 3.79 (AB spin systems, 2H, dA 3.67 and dB 3.91 ppm, CH2N, 2JHH 14.6 Hz), 7.33 (m, 2H, H3), 7.56 (m, 4H, C6H4, H4,5), 8.02 (m, 2H, H6, 3J117/119SnH 101.3/116.2 Hz). 13C NMR (CD2Cl2, 75.46 MHz) d [ppm]: 46.03 (s, NCH3), 47.06 (s, NCH3), 63.51 (s, CH2N, 3JSnC 51.8 Hz), 128.34 (s, C3), 129.10 (s, C5), 131.32 (s, C4, 4JSnC 19.2 Hz), 134.84 (s, C6, 2JSnC 58.1 Hz), 135.93 (s, C2), 140.18 (s, C1), NCS reso-nance was not observed. 119Cl , 111.9 MHz), d [ppm]:404.1

(quintet,1JNSn152.2Sn (CD2772_

Hz);Se (CD2Cl2, 57.24MHz)

d [ppm]: _356.9s. 1H NMR (CDCl3, 300 MHz) d [ppm]: 2.07 (s, br., 6H, NCH3), 2.46 (s, br., 6H, NCH3), 3.72 (AB spin systems, dA 3.60 and dB 3.84 ppm, CH2N, 2JHH 14.6 Hz), 7.22 (m, 2H, H 3), 7.46 (m, 4H, C 6H4, H4,5), 7.96 (m, 2H, H6). 119Sn (CDCl3, 111.9 MHz), d [ppm]: _406.9s, br. 77Se (CDCl3, 76.31 MHz) d [ppm]: _350.3s. MS (APCI, CH3CN), m/z (%): 494.02 (100) [M _ NCSe]. MS (ESI_, CH3CN), m/z (%): 702.05 (100) [M NCSe]_.

Compounds 8e10 were put in evidence in the mixture obtained by a similar protocol as in case of compounds 1e3:[2-(Me2NCH2)C6H4]PhSnCl(NCS) (8) from NH4SCN (0.072 g, 0.94 mmol) in water (10 mL) and [2-(Me2NCH2)C6H4]PhSnCl2 (0.378 g, 0.94 mmol) in dichloromethane (10 mL), as a colorless oily product. Identified in mixture with 5 and [2-(Me2NCH2)C6H4] PhSnCl2. 1H NMR (CDCl3, 400 MHz) d [ppm]: 2.23 (s, 6H, NCH3), 3.72 (s, 2H, CH2N), 7.26 (m, 1H, C6H4, H3), 7.47e7.52 (m, 5H, C6H4, H4,5 C6H5-meta para), 7.62 (m, 2H, C6H5-ortho) 8.19 (br., 1H, C6H4, H6, 3JSnH 91.8 Hz). 119Sn (CDCl3, 111.9 MHz) d [ppm]: _168.00s, br. MS (APCI, CH3CN), m/z (%): 366.01 (100) [{2-(Me2NCH2)C6H4} PhSnCl].

[2-(Me2NCH2)C6H4]2SnCl(NCS) (9) from NH4SCN (0.061 g, 0.80 mmol) in 10 mL water and [2-(Me2NCH2)C6H4]2SnCl2 (0.182 g, 0.40 mmol) in 20 mL dichloromethane. Identified in mixture with 6 and [2-(Me2NCH2)C6H4]2SnCl2. 1H NMR (CD2Cl2, 400 MHz) d [ppm]: 2.09 (s, 6H, NCH3), 2.48 (s, 6H, NCH3), 3.71 (AB spin system with dA 3.58 and dB 3.84, 2H, CH2N, 2JHH 14.7 Hz), 3.76 (AB spin system with

dA 3.51 and dB 4.02, 2H, CH2N, 2JHH 14.4 Hz), 7.31 (m, 2H, C6H4, H3), 7.52 (m, 4H, C6H4, H4,5), 8.20 (m, 2H, C6H 4, H6, 3JSnH 108.98 Hz). 119Sn

(CD2Cl2, 149.21 MHz) d [ppm]: _330.0 (t, 1JNSn 146.2 Hz). MS (APCI, CH3CN), m/z (%): 423.06 (100) [{2-(Me2NCH2)C6H4}2SnCl]

[2-(Me2NCH2)C6H4]2SnCl(NCSe) (10) from KSeCN (0.049 g, 0.34 mmol) in water and [2-(Me2NCH2)C6H4]2SnCl 2 (0.156 g, 0.34 mmol) in benzene. Identified in mixture with 7 and [2-(Me2NCH2)C6H4]2SnCl2. 1H NMR (CDCl3, 300 MHz) d [ppm]: 2.07 (s, br., 6H, NCH3), 2.46 (s, br., 6H, NCH3), 3.52 (m, 2H, CH2N), 4.03 (m,

2H, CH2N), 7.22 (m, 2H, H3), 7.46 (m, 4H, C6H4, H4,5), 8.05 (m, 1H, H6) 8.17 (m, 1H, H6). 119Sn (CDCl 3, 111.9 MHz): d [ppm]: _329.8s, br. 77Se

(CDCl3, 76.31 MHz) d [ppm]: _346.6s. MS (APCI, CH3CN), m/z (%):423.06 (100) [{2-(Me2NCH2)C6H4}2SnCl].

X-ray structure determination

The details of the crystal structure determination and refine-ment are given in Table 4. The crystals were attached with paraton/ N oil to cryoloops and the data were collected on a Bruker SMART APEX diffractometer using Mo Ka radiation (l 0.71073 ) at 297 K. The hydrogen atoms were refined with a riding model and a mutual isotropic thermal parameter. The pendant arm in one of the 2-(Me2NCH2)C6H4 group in 10 is disordered over two positions with equal occupancy. The displacement parameters of C10eC15, C10AeC15A, N3, C19 and Se1 in 10 were restrained using DELU and SIMU. For structure solving and refinement the software package SHELX-97 was used [51]. p intermolecular interactions (p CHg-CH2/Cg in 4 and p Cg/Cg in 6, 7 and 10) were evidenced using the


Table 4

X-ray crystal data and structure refinement for compounds [2-(Me2NCH2)C6H4]Me2Sn(NCS) (1), [2-(Me2NCH2)C6H4]Me2Sn(NCSe) (2), [2-(Me2NCH2)C6H4]Ph2Sn(NCSe) (3), [2-(Me2NCH2)C6H4]nBuSn(NCS)2 (4), [2-(Me2NCH2)C6H4]2Sn(NCS)2 (6), [2-(Me2NCH2)C6H4]2Sn(NCSe)2 (7) and [2-(Me2NCH2)C6H4]2SnCl(NCSe) (10).

12346710

Empirical formulaC12H18N2SSnC12H18N2SeSnC22H22N2SeSnC15H21N3S2SnC20H24N4S2SnC20H24N4Se2SnC19H24ClN3SeSn

Formula weight341.03387.93512.07426.16503.24597.04527.51

Temperature (K)297(2)297(2)297(2)297(2)297(2)297(2)297(2)

Wavelength ()0.710730.710730.710730.710730.710730.710730.71073

Crystal systemOrthorhombicOrthorhombicMonoclinicMonoclinicMonoclinicMonoclinicMonoclinic

Space groupP2(1)2(1)2(1)P2(1)2(1)2(1)P2(1)/nP1 21/c1P2(1)/nP2(1)/nP21/c

Unit cell dimensions

a ()7.7758(7)7.8679(12)9.632(2)8.807(4)9.7467(17)9.8875(15)9.579(3)

b ()12.1569(10)12.2031(19)23.981(5)17.226(7)16.827(3)16.898(3)13.885(4)

c ()15.4074(13)15.695(2)18.802(4)12.808(5)13.344(2)13.465(2)16.590(5)

a (_ )90909090909090

b (_ )909092.126(4)107.346(6)93.398(3)93.173(3)105.848(5)

g (_ )90909090909090

Volume (3)1456.5(2)1506.9(4)4339.9(17)1854.8(13)2184.7(7)2246.2(6)2122.7(11)

Z4484444

Dc (g/cm3)1.5551.5551.5671.5261.5301.7651.651

Absorption coefficient1.8761.8762.8621.6001.3734.3903.051

(mm_1)

F(000)6807522016856101611601040

Crystal size, mm0.56 _ 0.34 _ 0.330.60 _ 0.52 _ 0.340.32 _ 0.30 _ 0.260.30 _ 0.28 _ 0.260.39 _ 0.34 _ 0.250.38 _ 0.33 _ 0.290.27 _ 0.26 _ 0.22

q Range for data2.13e25.002.11e25.011.70e25.002.04e25.001.95e25.002.39e25.001.95e25.50

collections (_ )

Reflections collected14,04214,09041,41817,50015,07621,01215,471

Independent reflections2574266576573267384839463962

[R(int) 0.0354][R(int) 0.0570][R(int) 0.0525][R(int) 0.0313][R(int) 0.0545][R(int) 0.0556][R(int) 0.046]

Refinement methodFull-matrix least-squares on F2

Data/restraints/2574/0/1492665/0/1497657/0/4733267/0/1933848/0/2483946/0/243962/0/313

parameters

Goodness-of-fit on F21.1711.1771.1661.1711.0531.0401.149

Final2R indicesRRRRRRR

21 0.0283,1 0.0503,1 0.0482,1 0.0406,1 0.0381,1 0.0377,1 0.0672,

[F> 2s(F )]wR2 0.0670wR2 0.1102wR2 0.0948wR2 0.0864wR2 0.0799wR2 0.0824wR2 0.1361

R Indices (all data)R1 0.0290,R1 0.0542,R1 0.0601,R1 0.0439,R1 0.0518,R1 0.0521,R1 0.0878,

Largest diff. peak andwR2 0.0674wR2 0.1119wR2 0.0992wR2 0.0882wR2 0.0846wR2 0.0867wR2 0.1444

0.811 and _0.3231.287 and _1.6080.877 and _0.6220.644 and _0.6520.835 and _0.4040.657 and _0.6441.153 and _1.104

hole, e _3

Platon program [52]. The drawings were created with the Diamond program [53].

Acknowledgements

Financial support from National University Research Council and Ministry of Education and Research of Romania (Research Projects PCCE-0050/2011 e Partner P3 and PD 443/2010) is acknowledged.

Appendix A. Supplementary material

CCDC 1018338, 1018337, 1018343, 1018344, 1021897, 1025186 and 1018339 for compounds 1e4, 6, 7 and 10 contain the supple-mentary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

Appendix B. Supplementary data

Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.jorganchem.2014.11.026.

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