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Reaction of the trimethylsilylated diamine ligand (Me3-Si)NHCH2CH2NH(SiMe3) with titanium@) precursors affords the novel distorted-tetrahedral complex [Ti(Me3-SiNCH2CH2NSiMe3)C12] which, when activated by methylaluminoxane, is an active ethene polymerisation catalyst.

The title compound, poly[aquacadmium-bis(#-nicotinato-mN:~O,t~O')], [Cd(C6H4NO2)2(H20)], consists of a polymeric network in which each nicotinate acts as a bidentate chelating ligand towards one Cd atom through its carboxylate group while simultaneously binding to a second Cd atom through its pyridine N atom. Cd has approximate pentagonal bipyramidal coordination geometry. Water acts as a ligand; it is also involved in hydrogen bonding to nearby carboxylate O atoms, contributing further to the polymeric network interactions. CommentThe structure of the title compound, (I), was determined as part of an investigation of the structural chemistry of carboxylate complexes of Group 12 metals. It is polymeric, with the nicotinate ligands binding through their N atoms and carboxylate functional groups. Each Cd atom is coordinated by four different nicotinate ligands, two through their N atoms and two in a chelating fashion through their carboxylate groups. Both these carboxylates are bound asymmetrically, with one Cd--O bond considerably longer than the other. The presence of one water ligand makes each Cd atom seven-coordinate. The coordination geometry can best be described as approximately pentagonal bipyramidal, with the carboxylates and one N atom in the equatorial plane (r.m.s. deviation for the five ligating atoms = 0.101 A; deviation of Cd from the mean plane = 0.163 A), and with the second N atom and the water ligand in axial positions. (I)The two crystallographically independent nicotinate ligands both show deviations from planarity, consisting mainly of a twist in the carboxylate group about the C--C bond out of the aromatic ring plane. The dihedral

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