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Metal Atom Synthesis of Metallaboron Clusters. 8. Synthesis of New Cobalt, Iron, and Nickel Clusters Derived from 2,6-C2B7H,,. Structural Characterization of 2-[ vs-C6(CH3)3H3]Fe-I,6-C2B7H9, 6-[ vs-C6(CH3)3H3]Fe-9,1 0-C2B7Hl1, and 5,7,8-(CH3)3-11,7,8,10-[ q3-C4(CH3)4H]NiC3B7H7 James J. Briguglio and Larry G. Sneddon" Department of Chemistry and the Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19 104 Received June 14, 1985
The reactions of thermally generated cobalt, iron, or nickel atoms with the nido-carborane 2,6-CzB7Hll and either cyclopentadiene, toluene, mesitylene, or 2-butyne were explored and found to yield a number of unique metallacarborane clusters. Reaction of the carborane with cobalt atoms and cyclopentadiene (I) and 4-(7-C5H5)Co-2,3-CzB7H13 (11) gave two new cobaltacarborane clusters 2-(q-C5H5)Co-1,4-CzB7H9 along with the known compounds 2-(q-C5H5)Co-6,9-CzB,Hg and 8-(~-C5H5)Co-6,7-CZB7H11. Reaction of 2,6-CzB7Hllwith iron atoms and toluene gave the closo $-arene complexes 2-(q6-CH3C6H5)Fe-6,9-C2B7H9 (111) and 2-($-CH3C6H5)Fe-1,6-C2B7Hg (IV) while reaction with mesitylene gave both closo, 2- [$(CH3)3C6H3]Fe-1,6-CzB7Hg (V),and nido, 6-[$-(CH3)3C6H3]Fe-9,10-C2B7Hll (VI), complexes. The structures of V and VI were confirmed by single-crystal X-ray crystallographic studies. Crystal data for V: space group R 1 / m ; 2 = 2; a = 8.179 (4) A, b = 10.952 (3) A, c = 8.949 (5) A; /3 = 114.65 (3)O; V = 728.6 A3. The structure was refined to a final R = 0.042 and R, = 0.049 for the 1243 reflections that had F: > 3a(F:). Crystal data for VI: space group P21212,; 2 = 4; a = 9.291 (4) A, b = 11.688 (6) A, c = 13.524 (2) A; /3 = 90.02 (3)"; V = 1468.6 A3. The structure was refined to a final R = 0.056 and R, = 0.055 for the 1180 The reaction of 2,6-C2B7Hllwith nickel atoms, toluene, and 2-butyne reflections having F: > 3a(F:). NiC3B7H, was found to produce the unique metallacarborane cluster 5,7,8-(CHJ3-11,7,8,10-[03-C4(CH3),H] (VII). A single-crystal X-ray study of the compound proved it to have a sandwich-type structure in which a nickel atom is bonded to both a q3-cyclobutenylgroup and a three-carbon carborane. Furthermore, the nickelacarborane cage has a slip distortion resulting in an open-cage geometry rather than the closo structure predicted by simple electron-counting rules. Crystal data for VII: space group P2,ln; 2 = 4; a = 9.537 (3) A, b = 13.892 (5) A, c = 14.695 (4) A; /3 = 106.83 (2)O; V = 1863.7 A3. The structure was refined to a final R = 0.072 and R , = 0.065 for the 1473 reflections that have F: > 3a(F:). Introduction Work in our laboratory has shown that metal atom reaction techniques can be successfully applied to the synthesis of new types of polyhedral metallaboron compounds not attainable by using more conventional synthetic procedures. Much of our previous work has employed reactive small cage systems such as B5H9,B6H10,or nido-2,3(CzH5)2CzB,H6 as reactants and has resulted in the production of a variety of new metallaborane,' -carborane,l-, and -thiaborane5s6clusters. Our recent work7 reporting the synthesis of new types of (q6-arene)ferraboranecompounds, as well as the first example of a ferraoxaborane cluster, derived from decaborane( 14) demonstrated that these techniques can also be used to generate new types of metallaboron clusters from higher boron cage systems. We are now further investigating such possibilities and report here the synthesis and structural characterization of a (1) Zimmerman, G . J.; Hall, L. W.; Sneddon, L. G.Inorg. Chem. 1980, 19,3642-3650. (2)Micciche, R.P.; Sneddon, L. G.Organometallics 1983,2,674-678. (3)Micciche, R.P.; Briguglio, J. J.; Sneddon, L. G.Organometallics 1984,3,1396-1402. (4)Briguglio, J. J.; Sneddon, L.G.Organometallics 1985,4,721-726. (5)Zimmerman, G.J.; Sneddon, L. G . J. Am. Chem. SOC. 1981,103, 1102-1111. (6)Micciche. R. P.: Carroll. P. J.: Sneddon. L. G . Ormnometallics 1985;Q 161S1623. ' (7)Micciche, R.P.; Briguglio,J. J.; Sneddon, L. G.Inorg. Chem. 1984, 23, 3992-3999.
number of unique metal-boron clusters derived from the nido-carborane 2,6-CzB7Hll.8 Experimental Section Materials and Procedures. Iron, cobalt, and nickel were obtained from Alfa Products/Ventron Division. Mesitylene and toluene were obtained from Baker Chemical Co. and MCB Inc. respectively. Cyclopentadiene was distilled from dicyclopentadiene. The carborane 2,6-C2B7Hll was prepared by using the method of PleBek, Hefmiinek, and Stibr.*,b All other reagents were commercially obtained and used as received. Preparative thin-layer chromatography was conducted on 0.5 mm (20 X 20 cm) silica gel F-254 plates (Merck). Boron-11 and proton Fourier transform NMR spectra at 32.1 and 100 MHz, respectively, were obtained on a JEOL PS-100 spectrometer equipped with the appropriate decoupling accessories. Proton NMR spectra, at 250 MHz, were obtained on a Bruker WH-250 Fourier transform spectrometer. Boron-11 and proton NMR spectra at 64.2 and 200 MHz, respectively, were obtained on an IBM WP2OOSY Fourier transform spectrometer. Boron-11 NMR spectra, at 115.5 MHz, were obtained on a Bruker WH-360 Fourier transform spectrometer located in the MidAtlantic Regional NMR Facility. All boron-11 chemical shifts (8)The compou6ds described herein have been numbered according to the recently proposed polyhedral cage nomenclature system. See: (a) Casey, J. B.; Evans, W. J.; Powell, W. H. Inorg. Chem. 1981, 20, 1333-1341. (b) Casey, J. B.; Evans, W. J.; Powell, W. H. Inorg. Chem. 1983,22,2228-2235. (c) Ibid. 1983,?2, 2236-2245. (9) (a) PleZjek, J.; Heiminek, S.; Stibr, B. Inorg. Synth. 1983, 22, 231-234. (b) Ibid. 1983,22,237-239.
0276-733318612305-0327$01.50/0 0 1986 American Chemical Society
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Briguglio and S n e d d o n
were referenced to BF3*O(C2H&(0.0 ppm) with a negative sign hexanes in benzene solution, resulted in three bands (R, 0.98,0.58, indicating an upfield shift. All proton chemical shifts were and 0.52). measured relative to internal residual benzene from the lock An additional separation of band 2 using a 30% hexanes in solvent (99.5% C6D6)and then referenced to Me4Si (0.00 ppm). benzene solution gave as the major products: 111, 2-(q6The 2-D IIB-IIB NMR spectra of 4-(q-C5H5)Co-2,3-CzB7Hl3 CH3C6H5)Fe-6,9-CzB7Hs, R 0.18, yellow, 7.1 mg, mass measure(11) were obtained at 64.2 MHz (Bruker Aspect 2000A with ment calcd for 12C:Hl+1B{6Fe 258.1343, found 258.1333 (major DisNMR version 820601 software) using a IlB shift correlated fragment at m / e 148 ((q6-CH,C6H5)Fe));IV, 2-(q6-CH,C6H5)FeCOSY experiment with N-type selection parameters. The sweep 1,6-CzB7H9,Rf 0.13, red, 8.7 mg, decomp mp 154 "C, mass meawidth in the F2direction was 10000 and that in the F, direction surement calcd for 12C91H,,11B~6Fe 258.1343, found 258.1333 was 5000. A total of 128 increments with an increment size of (major fragment a t m / e 148 ((q6-CH3C6H5)Fe)). 0.1 ms were collected, each slice having 512 F2 data points. The Isomerization of 2-(96-CH3C6H5)Fe-6,9-C2B7H9 A 5-mg data were zero filled once in the F, direction and subjected to sample of the 2-(~6-CH3CsH5)Fe-6,9-C2B,Hg (yellow) was sealed 2-D FT transformation with sine-bell apodization in both doin a Pyrex tube under vacuum and heated a t 75 "C for 1h. This mains.'O A total of 160 scans were taken for each increment and produced a red compound which was identified by its spectral the recycle time was 0.1 s. data as 2-(q6-CH3C6H5)Fe-1,6-c*B7Hg. High- and low-resolution mass spectra were obtained on a Reaction of Iron Vapor with Mesitylene and 2,6-C2B7Hll. Hitachi Perkin-Elmer RMH-2 mass spectrometer and/or a VG A solution of 1g of 2,6-C2B7Hllin 200 mL of mesitylene was placed Micromass 7070H mass spectrometer interfaced to a Kratos in the rotary metal atom reactor. After degassing, the solution DS50S data system. Infrared spectra were obtained on a Perwas warmed to -40 "C and maintained at that temperature for kin-Elmer 337 spectrophotometer. The melting points are unthe entire reaction. Iron vapor (-0.75 g) was condensed into the corrected. rotating solution over a 1-h period. Upon completion of metal The metal atom apparatus employed in these studies was based deposition, the dark slurry was warmed to room temperature and on a design by K1abunde1la and is described The stirred for an additional 0.5 h. Excess mesitylene was removed rotary metal atom apparatus used was purchased from Kontes in vacuo, and the reactor flask was flushed with N2(g). The (Model No. K-927550) and modified according to a design pubremaining black residue was extracted with methylene chloride, lished by Ittel and Tolman.12 filtered through a course frit, and concentrated. The crude Reaction of Cobalt Vapor with C5H6 and 2,6-CzB7HlI.A product mixture was initially separated by TLC on silica gel by solution of 1.0 g of 2,6-C2B7H1,dissolved in 10 mL of cyclousing benzene resulting in two bands (Ri0.95 and 0.76). Further pentadiene was placed at the bottom of the static reactor. Cobalt separation of band 2 using a 50% hexanes in benzene solution vapor (-0.75 g) was cocondensed with 20 mL of C,H,. Following gave as the major products: V, 2-[q6-(CH3)3CSH3]Fe-1,6-C2B7H9, metal deposition, the matrix was warmed to room temperature R, 0.31, pink, 1.3 mg, mp 165-180 "C dec, mass measurement calcd and stirred for 1 h. The mixture was separated by TLC on silica for 12Cl11Hz111B756Fe 286.1658, found 286.1662 (major fragment gel using a 50% hexanes in benzene solution resulting in the a t m/ e 176 ([ q6-(CH3)3C6H3] Fe)); VI, 6-[q6- (CH,) 3C6H3]Fe-9,lOisolation of the following new compounds: I, 2-(q-C,H5)Co-1,4C2B7Hll,R, 0.35, red, 3.2 mg, mp 134 "C, mass measurement calcd C2B7&, R 0.66 red, 2.0 mg, decomp mp 58 "C, mass measurement for 1zC111H2311B,56Fe 288.1814, found 288.1765 (major fragment calcd for "C7'H 14 B $ 9 C ~234.1075, found 234.1094 (major fragat m / e 176 ( [q6-(CH3),c6H3]Fe)).An additional compound was ment a t m / e 124 ((q-C5H5)Co));11, 4-(q-C5H5)Co-2,3-CzB7H13, R, isolated from the base line, using a methylene chloride solution, 0.48, yellow, 7.9 mg, mp 146-149 "C; mass measurement calcd from the original separation in insufficient amounts (
