NEW COORDINATIVELY UNSATURATED LUTETIUM MONO(ALKYL) AND BIS(ALKYL) COMPLEXES WITH A BIS(ORTHO)-CHELATING ARYLDIAMINE LIGAND - CRYSTAL-STRUCTURES OF [LUCL2(2,6-(ME(2)NCH(2))(2)C6H3)(MU-CL)(MU-LI(THF)(2))](2) AND [LU(MU-CL)(2,6-(ME(2)NCH(2))(2)C6H3)(CH(2)SIME(3))](2)

New complexes of lutetium and yttrium containing the monoanionic, terdentate ligand [2,6-(Me(2)NCH(2))(2)C6H3](-) (NCN) have been synthesized by substitution reactions starting from MCl(3) (M = Lu, Y). Reaction of MCl(3) (M = Y, Lu) with one equivalent of (NCN)Li affords the ate complexes [(NCN)MCl(2)(mu-Cl)(mu-Li(thf)(2))](2) (M = Lu (1a), Y (1b)) in which the terdentate ligand is bound in mel fashion and all three chloride atoms are retained in the product. Crystals of la are monoclinic (space group P2(1)/n, a=10.4559(4), b=21.6150(9), c = 12.1700(7) Angstrom, beta = 105.294(4)degrees, Z = 2, final R = 0.039 for 3695 observed reflections [I>2.5 sigma(I)]). Attempted substitution of chloride in the yttrium complex 1b by Me(2)SiCH(2)(-) leads to decomposition. However, reaction of 1a with Me(3)SiCH(2)Li gives the monoalkyl complex [(NCN)Lu-(mu-Cl)(CH(2)SiMe(3))](2) (2, 30% yield), in which the terdentate ligand is bound in a pseudo-facial manner. Crystals of 2 are triclinic (space group P1, a = 9.8575(7), b = 10.0171(7), c = 11.1460(14) Angstrom, alpha = 75.096(8), beta = 75.092(8), gamma = 77.474(6)degrees, Z = 1, final R(1) = 0.11 for 1361 reflections [I>2 sigma(I)]). Substitution of the chloride ions in 2 by Me(3)SiCH(2)(-) is possible and affords quantitatively the bisalkyl complex [(NCN)Lu(CH(2)SiMe(3))(2)] (3). The lutetium complexes 2 and 3 are formally coordinatively unsaturated complexes, which are moisture-sensitive and thermally stable for several weeks when dissolved in aromatic solvents. However, they decompose rapidly in aliphatic solvents such as hexane, and a decomposition route involving the formation of carbene species is proposed.