ORGANOTRANSITION-METAL METALLACARBORANES .46. MULTIDECKER SANDWICHES OF THE COBALT GROUP-METALS

The double-decker sandwich complex CpIr(2,3-Et(2)C(2)B(4)H(4)) (1a) w as prepared via deprotonation of nido-2,3-Et(2)C(2)B(4)H(6) to its mon o- or dianion and reaction with (CpIrCl2)(2) in THF and isolated as a colorless air-stable solid; the B(4)-chloro derivative 1b was also ob tained. Decapitation of 1a and 1b with TMEDA afforded colorless nido-C pIr(2,3-Et(2)C(2)B(3)H(5)) (2a) and its 4-chloro derivative 2b. Chlor ination of 1a by Cl-2 or N-chlorosuccinimide gave the symmetrical spec ies CpIr(2,3-Et(2)C(2)B(4)H(3)-5-Cl) (1c), which was decapped to yiel d nido-CpIr(2,3-Et(2)C(2)B(3)H(4)-5-Cl) (2C). The triple-decker compl exes CpIr(2,3-Et(2)C(2)B(3)B(2)-4[6]-Cl)IrCp* (3), an orange solid, a nd dark green CpIr(2,3-Et(2)C(2)B(3)H(2)-4[6]-Cl)CoCp* (5) were prepa red from 2a and nido-CpCo(2,3-Et(2)C(2)B(3)H(5)) (4a), respectively, by deprotonation and reaction with (CpIrCl2)(2) in THF. Reaction of t he 2c(-) anion with Rh(MeCN)(3)-Cl-3 gave the dark green tetradecker c omplex [CpIr(Et(2)C(2)B(3)H(2)-5-Cl)]2RhH (6). In an attempt to prepa re a heterotrimetallic Co-Rh-Ir tetradecker sandwich, a three-way reac tion involving the deprotonated anions derived from CpCo(2,3-Et(2)C(2 )B(3)H(4)-5-Cl) (4b) and 2c with Rh(MeCN)(3)Cl-3 was conducted. The de sired species (Et(2)C(2)B(3)H(2)Cl)RhH(Et(2)C(2)B(3)H(2)Cl)IrCp (7) a nd the tetradeckers [CpCo(Et(2)C(2)B(3)H(2)Cl)]2RhH (8) and 6 were is olated in small quantities from the product mixture; many other appare nt triple-decker and tetradecker products were detected via mass spect roscopy but were not characterized. All new compounds were isolated vi a column or plate chromatography and characterized via NMR, UV-visible , and mass spectroscopy and by X-ray crystal structure determinations of 1a and 3. Crystal data for 1a: space group C2/c; a = 28.890(5) Angs trom, b = 8.511(2) Angstrom, c = 15.698(4) Angstrom, beta = 107.61(2)d egrees; Z = 8; R = 0.049 for 1404 independent reflections having I > 3 sigma(I). Crystal data for 3: space group P2(1)/c; a = 11.775(4) Angs trom, b = 15.546(5) Angstrom, c = 15.500(5) Angstrom, beta = 103.16(3) degrees; Z = 4; R = 0.066 for 2635 independent reflections having I > 3 sigma(I).