the crystal and molecular structure of nitrosylbis...

Journal of Crystallographic and Spectroscopic Research, Vol. 13, No. 1, 1983

The crystal and molecular structure of nitrosylbis (N,N-diethyldithiocarbamato) o-

phenylenebis(dimethylarsine)molybdenum(II) tetrafluoroborate

GEORGE FERGUSON* and A R P A D SOMOGYVARI Department of Chemistry, University o f Guelph

Guelph, Ontario N1 G 2 W1 Canada

(Received July 8, 1982 )

Abstract

Crystals of [NOMo(S2CNET2)2diars]�9 are monoclinic, space group I 2 / a with eight molecules in a unit cell of dimensions a = 25.808(5), b = 11.017(2), c = 23.275(5) A, and B = 108.10(2) ~ The structure was solved by the heavy- atom method and refined by full-matrix least-squares calculations with anisotropic thermal parameters. R = 0.048 for 2038 reflections w i t h / > 3o(1). The crystal structure contains discrete ions separated by normal van der Waals distances. The Mo atom has a distorted pentagonal bipyramidal geometry with the NO group and one S atom axial. Principal dimensions are: Mo-As 2.634(2) and 2.626(2); Mo-S(eq) 2.535(4), 2.530(4), and 2.503(3); Mo-S(ax) 2.552(4); Mo-N 1.78(1); N-O 1.19(1)A; and M o - Y - O 175.9(9) ~

Introduct ion

Coordination number seven dominates much of the coordination chemistry of molybdenum(II) (Drew, 1977; Kepert, 1979; Coucouvanis, 1979). Present descriptions rely on three idealized geometries: capped octahedron, capped trigonal prism, and pentagonal bipyramid. Because of the shallow potential energy minima associated with these geometries (Hoffman et al., 1977), much of the stereochemistry of seven coordination is concerned with polytopal isomerizations (Muetterties and Guggenberger, 1974; Brown et al., 1978; Davis et al., 1971). Crystal structure analyses provide an

49

0277-8068/83/0200-0049503.00/0 �9 1983 Plenum Publishing Corporation

50 Ferguson and Somogyvari

unambiguous way to determine precise details of molecular geometry, and the paucity of structural data for complexes of the type [XMo(L-L)2(L'-L')]- (where L-L is a uni-negative bidentate ligand and L ' -L ' is a neutral chelate) promped our previous investigation of COMo(S2CNMe2)2diars (Alyea et al., 1982). We report here details of the isostructural nitrosyl complex [NOMo(S2CNEt2)2diars]+BF4.

Experimental

Slow crystallization of [NOMo(S2CNEt2)2diars] (BF4) (Alyea et al., 1982) from a saturated nitrobenzene solution afforded bright yellow plate crystals. A crystal of approximate dimensions 0.35 • 0.16 • 0.06 mm was chosen for X-ray analysis. Accurate unit cell dimensions were obtained by a least-squares procedure applied to the setting angles for 25 general reflections, with 0 - - 10-15 ~ measured on an Enraf-Nonius CAD-4 diffractometer. Crystal data: C20H36AsEBF4MoN3OS4, M = 795.4, monoclinic, a = 25.808(5), b = II.017(2), c = 23.275(5) A, /3 = 108.10(2) ~ V = 6290.5 A 3, F(000) = 3184, Z = 8, Dc = 1.68, k(Mo Ka) = 0.71069 A, #(Mo Ka) = 21.0 cm -1. Systematic absences (hkl absent if h + k+ l = 2n + l, h 0l absent ifh = 2n + 1 and l = 2n + I) allow the space group to be I2/a (C6h, No. 15) or Ia (C 4, No. 9) (nonstandard settings of C2/c or Cc); I2/a was assumed and confirmed by the analysis. The cell data for the C2/c cell are; a = 28.890(5), b = 11.017(2), c = 25.808(5)/~,/3 = 130.03(1) ~ The intensities of the unique reflections with 2 ~ ~< 0 ~< 20 ~ were surveyed; of the 2919 unique reflections measured, the 2038 with I ~ 3a(I) were labeled observed, and the remainder excluded from refinement calculations. The data were corrected for Lorentz, polarization, and absorption effects. The transmission coefficients were in the range 0.71 to 0.87.

Theostructure was solved by the heavy-atom method from phases originally derived from the coordinates of the molybdenum and arsnic atoms whose positions were deduced from a three-dimensional Patterson synthesis. The structure was then refined (Sheldrick, 1976) 1 with isotropic thermal parameters by full-matrix least-squares calculations to R = 0.063. A dif- ference Fourier synthesis at this stage revealed the positions of all hydrogen atoms close to those expected on geometrical grounds. These were then positioned geometrically (C-H = 1.08 /~), and only an overall isotropic thermal parameter was refined for each type (i.e., CH3, CH2, phenyl CH) of hydrogen atom in subsequent refinement cycles. The BF4 anion was refined isotropically as a rigid group because of disorder problems with the fluorine atoms (B-F 1.35 A, F �9 �9 �9 F 2.03 A). Refinement converged with R = 0.048

1All numerical calculations were performed using the SHELX system of programs.

Structure of C20H36As2BF4MoN3OS4 51

and Rw = (Xw A 2/XwF2) 1/2 = 0.055 using anisotropic thermal parameters for all atoms not geometrically positioned. In the least-squares calculations, the weights used were based on counting statistics; scattering factors were taken from Cromer and Mann (1968) and Stewart et al. (1965), and the anomalous dispersion corrections were made for Mo and As (Cromer and Liberman, 1970).

Atomic coordinates of all atoms are given in Table 1. Interatomic distances and angles are given in Table 2; Table 3 gives mean plane data, and Tables 4a and 4b list the thermal parameters. A list of calculated and observed structure factors has been deposited. Figure 1 and 2 show respectively an ORTEP (Johnson, 1971) plot of the molecule with our numbering scheme and a stereodiagram of the unit-cell contents.

D i s c u s s i o n

The structure of [NOMo(S2CNEt2)2diars] § (BF4)- consists of discrete monomeric units separated by normal van der Waals distances (Fig. 2, Table 2). No crystallographic symmetry is required of the cation. The dithiocarbamate (dtc) and the diars ligands are both bidentate, and the immediate coordination sphere around the molybdenum is a slightly distorted pentagonal bipyramid, with As(l), As(2), S(1), S(2), and S(4) forming the equatorial plane (Table 3), and the nitrosyl group and S(3) axial. Intra- molecular contacts and geometrical constraints imposed by the axial- equatorial dithiocarbamate ligand cause a slight ruffling of the equatorial plane (deviations range from +0.29 A [S(4)] to -0.22 A [S(2)].

The Mo-N(3) [ 1.78( 1)] and N(3)-O [ 1.19(1)A] distances are normal and compare well with distances [Mo-N 1.778(6), N-O 1.19(1) A] reported for ~-N,N(CH3)2{ CpMo(NO)I}2 (Mallinson et al., 1980) although such distances vary somewhat [Mo-N 1.763(6), N-O 1.224(8) A in (NO)2Mo2(O;Pr)6 (HNMe2)2 (Chisholm et al. , 1980); Mo-N 1.731(8), N-O 1.154(9) A in NOMo(S2CN~Bu2)3 (Brennan and Bernal, 1973)]. The Mo-N(3)-O moiety is essentially linear with Mo-N-O 175.9(9) ~

The Mo-S distances in the equatorial-equatorial dtc ligand do not differ significantly [2.535(4), 2.530(4) A] whereas those in the axial-equatorial ligand show a 0.05 A variation [2.552(4)ax, 2.503(3) eq A]. Such trends have been noted previously for NOMo(S2CN~Bu2)3 (Brennan and Bernal, 1973) and COMo(S2CNMe2)2diars (Alyea et al . , 1982). The size of the differences is less than reported previously, suggesting that electron density is more evenly distributed within the dtc moiety. Also to be noted is that the axial Mo-S(3) bond length [2.552(4) A] is significantly less (15o) than the corresponding bond length [2.613(1) A] found for the COMo(S2CNMe2)2diars complex


0

4" 0

X

0

X

0

"N

<

I I I I I 1

I

~ ~ ~ Z Z ~ ~

Structure of C20H3~As2BF~MoN~OS~ 53

~ 1 L I E ~ ~ ~ ~

I I I I


Table 2. Intcratomic distances (A) and Angles (deg) with estimated standard deviations in parentheses

Bond distances

Mo-As(1) 2.634(2) N(1)-C(1) 1.29(2) Mo-As(2) 2.626(2) N(1)-C(2) 1.52(2) Mo-S(1) 2.535(4) N(1)-C(4) 1.52(2) Mo-S(2) 2.530(4) N(2)-C(6) 1.30(1) Mo-S(3) 2.552(4) N(2)-C(7) 1.46(2) Mo-S(4) 2.503(3) N(2)-C(9) 1.54(2) Mo-N(3) 1.777(11) N(3)-O 1.19(1) As(1)-C(11) 1.96(1) C(2)-C(3) 1.47(2) As(1)-C(12) 1.96(1) C(4)-C(5) 1.29(2) As(1)-C(15) 1.93(1) C(7)-C(8) 1.45(2) As(2)-C(13) 1.98(1) C(9)-C(10) 1.42(2) As(2)-C(14) 1.91(1) C(15)-C(16) 1.42(2) As(2)-C(20) 1.94(1) C(15)-C(20) 1.36(2) S(1)-C(1) 1.71(1) C(16)-C(17) 1.40(2) S(2)-C(1) 1.71(1) C(17)-C(18) 1.34(2) S(3)-C(6) 1.74(1) C(18)-C(19) 1.43(2) S(4)-C(6) 1.72(1) C(19)-C(20) 1.38(2)

Bond angles

As(1)-Mo-As(2) 74.7(1) S(1)-Mo-S(2) 67.6 (1) As(1)-Mo-S(1) 146.0(1) S(1)-Mo-S(3) 91.1(1) As(1)-Mo-S(2) 146.1(1) S(1)-Mo-S(4) 137.6(1) As(1)-Mo-S(3) 87.0(1) S(1)-Mo-N(3) 98.5(3) As(1)-Mo-S(4) 72.8(1) S(2)-Mo-S(3)- 89.0(1) As(1)-Mo-N(3) 86.9(3) S(2)-Mo-S(4) 74.2(1) As(2)-Mo-S(1) 71.6(1) S(2)-Mo-N(3) 91.5 (3) As(2)-Mo-S(2) 139.2(1 ) S(3)-Mo-S(4) 70.0(1 ) As(2)-Mo-S(3) 93.4(1) S(3)-Mo-N(3) 169.9(3) As(2)-Mo-S(4) 144.1(1) S(4)-Mo-N(3) 100.3(3) As(2)-Mo-N(3) 86.9(3) Mo-As(1)-C(11) 120.7(4) Mo-As( D-CO 2) 111.4(4) Mo-N(3)-O 175.9(9) Mo-As(1)-C(15) 112.1(4) S(1)-C(1)-S(2) 111.1(8) C(11)-As(1)-C(12) 105.8(4) S(1)-C(1)-N(1) 123(1) C(11)-As(i)- C(15) 102.1(6) S(2)-C(1)-N(1) 126(1) C(12)-As(1)-C(15) 103.1(6) N(1)-C(2)-C(3) 112(1) Mo-As(2)-C(13) 115.1(4) N(1)-C(4)- C(5) 114(2) Mo-As(2)-C(14) 115.3(5) S(3)-C(6)-8(4) 114(7) Mo-As(2)-C(20) 114.3(4) S(3)-C(6)-N(2) 125(1) C(13)-As(2)-C(14) 104.7(7) S(4)-C(6)-N(2) 120(1) C(13)-As(2)-C(20) 103.5(6) N(2)-C(7)-C(8) 114(1) C(14)-As(2)-C(20) 102.4(6) N(2)-C(9)-C(10) 111(1) Mo-S(1)-C(1) 9 0 . 6 ( 5 ) As(1)-C(15)-C(16) 121(1) Mo-S(2)-C(1) 9 0 . 7 ( 5 ) As(1)-C(15)-C(20) 121(1) Mo-S(3)-C(6) 8 7 . 2 ( 4 ) C(16)-C(15)-C(20) 118(1) Mo-S(4)-C(6) 8 8 . 6 ( 4 ) C(15)-C(16)-C(17) 120(1) C(1)-N(1)-C(2) 122(1) C(16)-C(17)-C(18) 120(2) C(1)-N(1)-C(4) 121(1) C(17)-C(18)-C(19) 121(2) C(2)-N(1)-C(4) 117(1) C(18)-C(19)-C(20) 118(1) C(6)-N(2)-C(7) 124(1) As(2)-C(20)-C(15) 116(1) C(6)-N(2)-C(9) 120(1) As(2)-C(20)-C(19) 121(1) C(7)-N(2)-C(9) 116(1) C(15)-C(20)-C(19) 123(1)

Structure of C2oH36As2BF4MoN3OS4 55

Table 2. Continued

As(l) �9 �9 �9 As(2) As(l) - .S(3) As(l) . . S(4) As(l) . . N(3) As(2) �9 �9 S(1) As(2) . .S(3) As(2) .-N(3) S(1)-- �9 S(2)

Intramolecula_r nonbonded distances

3.192 S(1) .- �9 S(3) 3.632 3.569 S(1) . . . N(3) 3.302 3.050 S(2) -. �9 8(3) 3.563 3.097 S(2) �9 �9 �9 S(4) 3.037 3.018 S(2).- �9 N(3) 3.130 3.770 S(3) . . - S(4) 2.903 3.240 S(4) �9 �9 �9 N(3) 3.320 2.818

(Alyea et al., 1982). This implies a larger t rans influence for CO than for N O in these types of Mo( I I ) complexes and suggests tha t r ea r rangemen t s by par t i a l d i ssoc ia t ion of a dtc l igand should be more facile for ca rbony l complexes than for ni t rosyl complexes .

The a t o m s o f each MoS2CNC2 unit a re close to being c o p l a n a r (Table 3), the dev ia t ions f rom p lana r i t y being less for the e q u a t o r i a l - e q u a t o r i a l d tc l igand t han for the a x i a l - e q u a t o r i a l l igand. The d ihedra l angles be tween the equa to r i a l c o o r d i n a t i o n p lane and the MoS2CNC2 units are 7.8 ~ for the e q u a t o r i a l - e q u a t o r i a l d tc uni t and 86.1 ~ for the a x i a l - e q u a t o r i a l d tc unit. Both as a result of c rowding in the equa to r i a l c oo rd ina t i on sphere and the "bi te" of the a x i a l - e q u a t o r i a l d tc g roup , S(4) lies 0.29 )k above the p lane t o w a r d ax ia l sulfur S(3). This d i sp lacement is s l ightly less than the cor res - p o n d i n g dev ia t ion (0.32 A ) found in COMo(S2CNMe2)2diars (Alyea et al. , 1982). The pucke r ing of the equa to r i a l c o o r d i n a t i o n p lane is more severe in the ca rbony l der ivat ive (Alyea et al., 1982) than repor ted here, t empt ing the sugges t ion tha t e lec t romer ic effects are of some consequence. The axia l M o - S(3) bond is not qui te pe rpend icu la r to the coo rd ina t i on plane [ S ( 3 ) - M o - N ( 3 ) 169.9(3)~ an exact ly ana logous s i tua t ion was found in the ca rbony l der ivat ive where the co r re spond ing angle S - M o - C O is 167.9(2) ~

Table 3. Mean-plane equations and atom displacements (A • 103)

Plane 1. Equation: 19.787x - 0.288y + 8.649z = 2.372 Mo -145, As(l) -152, As(2) 70, S(1) 150, S(2) -215, S(4) 292

Plane 2. Equation: 18.973x - 1.738y + 9.271z = 1.855 Mo -8, S(1) 12, S(2) 10, C(1) -2, N(1) -25, C(2) 6, C(4) 8

Plane 3. Equation: -14.311x + 3.180y + 21.276z = 0.976 Mo -59, S(3) 96, S(4) -55, C(6) 66, N(2) 47, C(7) 41, C(9) -136

Plane 4. Equation: 22.762x - 0.978), + 3.865z = 2.553 As(l) 0, As(2) -29, C(15) 3, C(16) -3, C(17) -10, C(18) -16, C(19) 14, C(20) 40


Table 4a. Anisotropic thermal parameters [Uil values (Mo and As • 104; S, O, and N • 10a, C • 102) A2]a

Ull U22 U33 U23 U13 U12

Mo 389(7) 348(7) 553(8) 14(6) 165(6) -12(6) As(I) 462(9) 416(9) 617(9) 2(7) 206(7) 33(7) As(2) 477(9) 414(9) 691(10) 39(7) 244(7) -32(7) S(1) 72(3) 48(2) 78(3) -6(2) 38(2) -7(2) S(2) 86(3) 50(2) 74(2) 4(2) 44(2) 3(2) S(3) 48(2) 44(2) 79(3) 2(2) 4(2) -8(2) S(4) 45(2) 40(2) 66(2) 5(2) 14(2) -5(2) O 45(6) 74(7) 87(7) -4(6) 3(6) -4(6) N(1) 93(10) 63(9) 66(8) 6(7) 35(8) 7(7) N(2) 51(8) 49(8) 79(8) 12(7) 2(7) 0(6) N(3) 36(7) 43(6) 69(8) 0(6) 21(6) 6(6) C(1) 6(1) 6(1) 5(1) 0(1) 3(1) 0(1) C(2) 10(1) 8(1) 9(1) -2(1) 5(1) 0(1) C(3) 16(2) 7(1) 12(2) -0(1) 7(1) 0(1) C(4) 17(2) 10(1) 13(2) 0(1) 10(2) 6(1) C(5) 27(4) 30(4) 32(4) 22(3) 22(3) 16(3) C(6) 4(1) 4(1) 6(1) 0(1) 0(1) 0(1) C(7) 7(1) 4(1) 8(1) 3(1) 1(1) 0(1) C(8) 9(1) 4(1) 17(2) -0(1) 5(1) 1(1) C(9) 8(1) 7(1) 10(1) !(1) 2(1) 1(1) C(10) 9(1) 11(2) 8(1) -1(1) 1(1) 1(1) C(11) 7(1) 7(1) 8(1) 1(1) 3(1) 4(1) C(12) 9(1) 6(1) 8(1) -2(1) 3(1) -2(1) C(13) 11(1) 5(1) 9(1) 3(1) 4(1) 3(1) C(14) 6(1) 11(1) 10(1) -2(1) 2(1) -4(1) C(15) 4(1) 7(1) 5(1) 0(1) 2(1) 1(1) C(16) 6(1) 6(1) 10(1) 1(1) 2(1) -0(1) C(17) 6(1) 10(2) 7(1) 10(1) 2(1) 1(1) C(18) 7(1) 9(1) 7(1) 4(1) 3(1) 2(1) C(19) 5(1) 7(1) 10(1) 0(1) 3(1) 1(1) C(20) 5(1) 5(1) 8(1) 2(1) 3(1) -1(1)

aui] values in theexpression exp [- 21r2(Ullh2a .2 + U22k2b .2 + Uaal2c .2 + 2U12hka*b* + 2U13hla*c* + 2U23klb*c*) ] .

Table 4b. Isotropic thermal parameters (Uis o A 2 X 102)

Atom Uis o Atom (H) Uis o

B 25(2) R-CH 3 16(1) F(1) 19(1) R2-CH2 8(2) F(2) 24(1) R3-CH 6(2) F(3) 32(1) F(4) 38(1)

Structure of C20H36As2BF4MoN3OS4

CI@

C6(

'C8

57

CS

CLI

$2 SO: C1LJ:

~Et~C 16C 17

C2 N3

cs

BS2c20

C13 Fig. 1. A view of the molecule with the numbering scheme.

C19

The N(1)-C(1) and N(2)-C(6) bond distances [1.29(2) and 1.30(1) A, respectively] are comparable with those reported for COMo(S2CNMe2)Ediars (Alyea et al., 1982) and reflect the partial double bond character of the bond (Breuen et al., 1976; Templeton and Ward, 1980). The S-C distances [ 1.71 ( 1)- 1.74(1) A] and the N - C (ethyl) distances [ 1.46-1.54(2) A] are also in the range previously reported (Brennan and Bernal, 1980; Alyeaet al., 1982; Templeton

c C

A ,A

Fig. 2. A stereoview of the crystal structure. The BF4 anion has very large thermal motion and the atoms are shown by spheres of an arbitrary size, for clarity.


and Ward, 1980). The ethyl C-C distances of the diethyldithiocarbamate ligands are all affected by thermal motion [bond lengths 1.29(2)-1.47(2) A]; the shortest distance is between atoms C(4) and C(5) which have very large thermal motion [mean Uiso for C(5) 0.30(4)•2].

The Mo-As distances [2.634 and 2.626(2) A] are longer than the distances [2.569 and 2.583(1) A] found in COMo(S2CNMe2)2diars and compare favorably with those found in rac and m e s o forms of (CO)3Mo[o- C6H4(AsMePh)2] [2.603, 2.663 and 2.595, 2.645(3) A] (Dewan et al . , 1975) and in [C1Mo(CO)2(diars)2] § [2.614 and 2.617(5) A] (Drew and Wilkins, 1973). The "bite" of the diars (3.192 A) is slightly larger than for COMo(S2CNMe:)2 diars (3.164/~) while the bite angle [74.7(1) ~ ] is comparable to those found [74.8-76.6(1)] previously (Alyea et al . , 1982; Dewan et al . , 1975; Drew and Wilkins, 1972). The C6H4As2 moiety is essentially planar (Table 3). The As-C distances [1.91-1.96(1) A] are close to those reported for similar complexes. The angles at arsenic range from 102.4 to 120.7 ~ , a smaller range than found in COMo(S2CNMe2)2diars. The Mo-As-C angles are larger than tetrahedral, whereas the C-As-C angles are less than tetrahedral (Table 2). Similar deformations have been reported previously and are indicative of crowding, by other ligands, around arsenic.

Acknowledgment

This work was supported primarily by grants from the National Research Council of Canada (to G.F.).

References

Alyea, E. C., Ferguson, G., and Somogyvari, A. (1982). Inorg. Chem. 21, 1372. Bottomly, F., Lin, I. J. B., and White, P. S. (1979)s Chem. Soc., Dalton Trans., 1726. Brennan, T. F., and Bernal, I. (1973) lnorg. Chim. Acta, 7, 283. Breuen, D. A., Gloss, W. K., and Burke, M. A. (1976) Spectrochim. Acta, Part A 32, 137. Brown, L. D., Datta, S., Kouba, J. K., Smith, L. K., and Wreford, S. S. (1978) Inorg. Chem. 17,

729. Chisholm, M. H., Huffman, J. C., and Kelly, R. L. (1980) lnorg. Chem. 19, 2762. Coucouvanis, D. (1979) Prog. Inorg. Chem. 26, 301. Cromer, D. T., and Liberman, D. L. (1970)3". Chem. Phys. 53, 1891. Cromer, D. T., and Mann, J. B. (1968)Acta Cryst. A 24, 321. Davis, R., Hill, M. N. S., Holloway, C. E., Johnson, B. F. G., and A1-Obaidi, K. H. (1971)s

Chem. Soc. (A ), 994. Dewan, J. C., Henrick, K., Kepert, D. L., Trigwell, K. R., White, A. H., and Wild, S. F. (1975) J.

Chem. Soc., Dalton Trans., 546. Drew, M. G. B. (1977) Prog. Inorg. Chem. 23, 67. Drew, M. G. B., and Wilkins, J. D. (1973) J. Chem. Soc., Dalton Trans., 2664. Hoffman, R., Beier, B. F., Muetterties, E. L., and Rossi, A. R. (1977)Inorg. Chem. 16, 511. Johnson, C. K. (1971) ORT~P 11, Oak Ridge National Laboratories, Technical Report ORNL-

3894, revised.

Structure of C~H36As2BF4MoN3OS4 59

Kepert, D. L. (1979) Prog. lnorg. Chem. 25, 41. MaUinson, P. R., Sim, G. A., and Woodhouse, D. I. (1980)Acta Cryst. B 36, 450. Muetterties, E. L., and Guggenberger, L. J. (1974) J. Am. Chem. Soc. 96, 1748. Sheldrick, G. M. (1976) University Chemical Laboratories, Cambridge, CB2 1EW, England. Stewart, R. F., Davidson, E. R., and Simpson, W. T. (1965) J. Chem. Phys. 42, 3175. Templeton, J. L., and Ward, B. C. (1980) Inorg. Chem. 19, 1753.

British Library Lending Division Supplementary Publication No. 66013 contains 10 pages of structure factor tables.

the crystal and molecular structure of nitrosylbis...

Documents