A CHANGE OF THE BONDING MODE OF THE ALUMOHYDRIDE GROUP IN BISCYCLOPENTADIENYLHYDRIDO REM COMPLEXES - FROM HETEROMETALLIC TO HOMOMETALLIC HYDRIDES - CRYSTAL AND MOLECULAR-STRUCTURES OF [(ETA-5-C5H5)2YB(MU-3-H)]2[(MU-2-H)ALH2.N(C2H5)3]2.C6H6, [(ETA-5-C5H5)2LU(MU-2-H)]2[(MU-2-H)2ALH.N(C2H5)3]2.C6H6 AND [(ETA-5-C5H5)2LU]3(MU-2-H)2(MU-3-H)

Slight variations of the experimental conditions result in inclusion of non-coordinated benzene molecules into the structures of lutetium and ytterbium alumohydride complexes bringing about resistance to X-ray irradiation in contrast what is found in the benzene-free lutetium complex. X-ray structural determinations of [eta-5-C5H5)2Yb(mu-3-H)]2[(mu-H)A1H2.N(C2H5)3]2.C6H6 (I) (monoclinic crystals: a = 13.307(2), b = 15.538(2), c = 14.075(2) angstrom, gamma = 134.53(1)-degrees, space group P2(1)/a, Z = 4) and [(eta-5-C5H5)2Lu(mu-2-H)]2[(mu-2-H)2A1H.N(C2H5)3]2.C6H6 (II) (monoclinic crystals: a = 11.339(2), b = 13.300(2), c = 14.061(2) angstrom, gamma = 102.28(1)-degrees, space group P2(1)/b, z = 4) revealed that the former has a classical structure of the adduct between [Cp2Ln(mu-H)]2 and triethylamine with both two mu-3-, and mu-2-bridging hydrogens. REM of II is additionally coordinated with one more hydrogen thus increasing its coordination number to 10 with concomitant weakening of the bonding between the dimeric lutetiecene and alane. In excess of triethylamine, complex II decomposes to yield a mixture of [Cp2Lu(mu-H).NEt3]2 (VI) and [(eta-5-C5H5)2Lu]3(mu-2-H)2(mu-3-H) (VII). The latter, according to X-ray data (hexagonal crystals: a = 16.193(3), c = 10.640(1) angstrom, space group P3(1)2(1)2, Z = 3), has a triangular metal core with central mu-3-hydrogen.