atoms: 97 refined parameters, R = 0.0568, Rw = 0.0513. Further details of the crystal structure investigation may he obtained from the Fachinfor- mationszentrum Karlsruhe. Gesellschaft fur wissenschaftlich-technische Information mbH, W-7514 Eggenstein-Leopoldshafen 2 (FRG), on quot- ing the depository number CSD-320147, the names of the authors, and the journal citation.

[6] M. Atoji, W. N. Lipscomb, Acfa CrysfaNogr. 6 (1953) 547. [7] G. Maier. S. Pfriem, U. Schafer, R. Matusch, Angew. Chem. 90(1978) 552;

Angew. Chem. Int . Ed. Engl. 17 (1978) 520. [S] H. Irngartinger, A. Goldmann, R. Jahn, M. Nixdorf, H. Rodewald, G.

Maier, K.-D. Malsch, R. Emrich, Angew. Chem. 96 (1984) 967; Angew. Chem. Int. Ed. Engl. 23 (1984) 993.

(91 D. A. Kleier, J. Bicerano, W. N. Lipscomb, Inorg. Chem. 19 (1980) 216. [lo] T. Mennekes, P. Paetzold, R. Boese, Angew. Chem. 102(1990) 909; Angewj.

[Il l R. Boese, P. Paetzold, A. Tapper, R. Ziembinski, Chem. Ber. 122 (1989) Chum. Inf . Ed. Engl. 29 (1990) 899.

1057.

closo-Azadodecaborane, NB, ,HI ** By Jens Muller, Jan Runsink, and Peter Paetzold*

Rhombohedrally distorted B,, icosahedra are the build- ing blocks of elemental boron, anions with exact icosahedral symmetry are found in solutions of Na,[B,,H,,], and well- known examples of the three isomeric dicarbadodecabo- ranes C,B,,H ,, are heterododecaboranes containing dis- crete neutral icosahedral units. The carbon atoms in the latter compounds represent the most electronegative element of coordination number 6 found in molecules. Is it possible to incorporate the still more electronegative element nitro- gen as a heteroatom into an icosahedral framework isoelec- tronic to C,B,,H,, and Bl2Hf? to give a compound with the composition NB,,H,,?

We have repeatedly attempted to carry out such a synthe- sis in analogy to that of 1,2-C,Bl,H,,, which involves clo- sure of the open arachno structure of B,,H,,L, (L = Lewis base) by incorporation of the two C atoms of acetylene. Unfortunately, use of iminoboranes['] such as MeB =:Me, isoelectronic to acetylene, has been unsuccessful. The imi- noboranes undergo oligomerization more rapidly than reac- tion with B,,H,,L,. However, our recent preparation of nido-NB,,H,, (1)IzJ opened up the possibility of closing the nido framework of 1 with a BH fragment.I3I Addition of BH, to 1 should result in comproportionation of two of the hy- dridic H atoms of BH, with the two protonic bridging H atoms of 1 to give H,.

Indeed, the open cluster borane 1 can be closed by treat- ment with an excess of Et,N.BH, at 140°C [Eq. (I)]. The initial product was the ionogenic compound 2, however, formed in quantitative yield.[,] Reaction of 2 with HBF, affords the corresponding acid 3, our target molecule, as a sublimable, colorless [Eq. (2)].

The constitution of 3 was.established by NMR spectrosco- py. Three ' 'B NMR doublets in a ratio of 5: 5 : 1 15] are indic- ative of a B,, framework with fivefold symmetry and 11 terminal H atoms. The 2D "B-''B NMR spectrum con- firms that a set of five equivalent B atoms (B7 to B11) is bonded to a second such set (B2 to B6) as well as to a single

I*] Prof. Dr. P. Paetzold, J. Muller Institut fur Anorganische Chemie der Technischen Hochschule Templergraben 55, W-5100 Aachen (FRG) Dr. J. Runsink Institut fur Organische Chemie der Technischen Hochschule Templergraben 55, W-5100 Aachen (FRG)

[**I This work was supported by the Deutsche Forschungsgemeinschaft.

*Et3N.BH3 ntdo -NBqoHq3 -2H2 [E~~NHI INB~~HI~I (11

1 2

2 *HBFL

-IEt3NHIBF4 - doSO-NBl1Hl2 (21

3

1 3

B atom (B12) on the C, axis. Moreover, no cross-peak, which would have indicated a bond between B12 and the atoms B2 to B6, is observed. The coupling constants JBH = 177,147, and 150 Hz for B2 to B6, B7 to B1 1, and B12, respectively, reveal that the B-H bonds in proximity to the N atom are stronger than the others. For closo-l-methyl-l- phosphadodecaborane, MePB,,H, ', which is comparable to 3, the corresponding coupling constants (164, 150, and 150 Hz)I6I show the same trend. The overlapping quartets for the three kinds of H atoms cannot be resolved in the 'H NMR spectrum; however, their chemical shifts 15] may be determined from the three cross-peaks in the 2D "B-'H NMR spectrum. The N-bonded H atom gives rise to a 1 : 1 : 1 triplet in the 'H NMR spectrum with JNH = 62.5 Hz, a con- sequence of the symmetrical charge distribution around the I4N atom on the C, axis.

The title compound is thus the first cluster molecule con- taining a sixfold coordinated N atom in the framework.

Experimental Procedure 3: Compound 1 (0.50 g) [2] was dissolved in triethylamine-borane (1 .OO g) and the resulting solution was heated at 140°C for 3.5 h. Removal of the excess Et,N.BH, in vacuum affords the NMR-spectroscopically pure product 2, which was dissolved in 5 mL of a 54% solution of HBF, in diethyl ether. The solution was extracted with 5 x 20 mL of toluene and the combined toluene extracts were evaporated to dryness. Sublimation of the residue at 5O0C/0.O01 Torr gave 0.25 g (47%) of 3.

Received: August 24, 1990 [Z 4150 IE] German version: Angew. Chem. 103 (1991) 201

CAS Registry numbers:

16872-11-0. 1,131179-98-1~2,131180-01-3;3,131179-99-2; Et,N. BH,, 1722-26-5; HBF,,

[I] P. Paetzold, Adv. Inorg. Chem. 31 (1987) 123. [2] J. Miiller, P. Paetzold, R. Boese, Hereroarom Chem. 1 (1990) 461. [3] N. N. Greenwood, J. H. Morris, Proc. Chem. SOC. 1963, 338; J. S. Beck,

A. P. Kahn, L. G . Sneddon, Organometallics 5 (1986) 2552. 141 2: NMR spectra in CD,CI, at 25 "C; 'H NMR (300 MHz, TMS)- b = 1.28

(t, J =7.2 Hz, 9 H ; CH,), 1.79 and 1.98 (H on 82 to B11 and H on 812, respectively; measured and assigned as cross-peaks in the 2D "B-'H NMR spectrum), 3.08 (q, J=7 .2Hz with d, J = 5.0Hz. 6H; CH,). 7.6 (broad, 1 H; NH). "B NMR (96.23 MHz, Et,0.BF3): 6 = - 10.3 (d, J = 147 Hz. 10B; B2 to Bll), - 1.0 ( d , J = 137Hz, 1 B; B12).

[5] 3: NMR spectra in C,D6 at 25°C; 'H NMR (300 MHz, TMS): b = 1.91, 2.46, 3.19 (H on B2 to B6, on B7 to B11, on B12; for measurement and assignment, see [4]), 2.95 (t; NH). ''B NMR (96.23 MHz, Et,O.BF,): 6 = - 11.9 (d, Y , , ~ = 55 Hz; 87 to Bll) , - 9.8 (d, vli2 = 106 Hz; B2 to 86). 2.7 (d; B12). I4N{'H} NMR (5.79 MHz, CH3N02): 6 = - 282 ( v l i 2 = 78 Hz). IR(CC1,): B [cm-']= 3299 (NH), 2622,2579 (BH).

3612. [6] T. D. Getmen, H.-B. Deng, L.-Y. Hsu, S. G. Shore, Inorg. Chem. 28 (1989)

Angeu. Chem. Ini. Ed. Engl. 30 (1991) No. 2 6 VCH Verlagsgesellschafi mbH, W-6940 Weinheim, 1991 0570-0833~9!/0202-0175 3 3.50+ ,2510 175