Organotransition-metal Metallacarboranes 2

Reactions of the (1,3,5-cyclooctatriene)ferracarborane complex (η6-C8H10)Fe(R2C 2B4H4) (R = C2H5) with benzene or other arenes over AlCl3 form the corresponding (η6-arene)Fe(R2C2B4H 4) species, as air-stable crystalline solids. Complexes in which the arene is benzene, 1,3,5-trimethylbenzene (mesitylene), and hexamethylbenzene have been characterized via 13C, 1H, and 11B FT NMR, IR, and mass spectroscopy and X-ray crystal structure determinations. In all cases the arene ring is planar, centered over the metal, and nearly parallel to the C2B3 ring of the carborane ligand. The benzene complex crystallizes with two molecules in the asymmetric unit, one of which is eclipsed with respect to the C(2)-C(3) bond of the carborane ligand while the other is staggered. The mesitylene and hexamethylbenzene complexes are approximately staggered and eclipsed, respectively. The reaction of (η6-C8H10)Fe[(C2H 5)2C2B4H4] with N,N,N′N′-tetramethyl-1,2-diaminoethane results in extraction of the apex boron and forms (η6-C8H10)Fe-[(C2H 5)2C2B3H5], characterized from spectroscopic data as a sandwich complex containing a planar carborane ligand. Crystal data: (η6-C6H6)Fe[(C2H 5)2C2B4H4], Mr = 264, space group Pbca, Z = 8 (two molecules/ asymmetric unit), a = 14.187 (5) Å, b = 15.796 (6) Å, c = 24.714 (10) Å, V = 5538 Å3, R = 0.069 for 3124 reflections having F0 2 \u3e 3σ(F0 2); [η6-C6(CH3)3H 3]Fe[(C2H5)2C2B 4H4], Mr 306, space group P21/n, Z = 4, a = 7.610 (2) Å, b = 14.646 (4) Å, c = 15.348 (7) Å, β = 95.95 (4)°, V = 1701 Å3, R = 0.063 for 2105 reflections having F0 2 \u3e 3σ(F0 2); [η6-C6(CH3)6]Fe[(C 2H5)2C2B4H4], Mr = 348, space group P21/n, Z = 4, a = 8.892 (1) Å, b = 13.250 (1) Å, c = 16.547 (4) Å, β = 98.51 (2)°, V = 1928 Å3, R = 0.047 for 2424 reflections having F0 2 \u3e 3σ(F0 2). © 1983 American Chemical Society