MONONUCLEAR AND DINUCLEAR TITANIUM(III) TITANIUM(IV) COMPLEXES WITH 1,4,7-TRIMETHYL-1,4,7-TRIAZACYCLONONANE(L) - CRYSTAL-STRUCTURES OF A COMPOSITIONALLY DISORDERED GREEN AND A BLUE FORM OF [LTICL3] - STRUCTURES OF [LTI(O)(NCS)2], [LTI(OCH3)BR2](CLO4), AND [L2TI2(O)2F2(MU-F)](PF6)

The coordination chemistry of titanium(III) and -(IV) with the macrocycle 1,4,7-trimethyl-1,4,7-triazacyclononane (L, C9H21N3) has been investigated. Reaction of TiCl3 with L in CH3CN at 20-degrees-C affords blue [LTiCl3] (1) whereas at elevated temperature green crystals (1a) were obtained. la is shown to consist of compositionally disordered crystals containing [LTiIIICl3] and probably an [LTiIV(O)Cl2] impurity. The crystal structures of 1 and la have been determined. Crystal data for 1 and, in brackets, for la: space group P2(1)/c (P2(1)/c), a = 12.365 (5) angstrom (12.430 (8) angstrom), b = 7.348 (2) angstrom, (7.337 (3) angstrom), c = 15.897 (3) angstrom (15.929 (5) angstrom), beta = 90.06 (2)-degrees (90.19 (3)-degrees), V = 1443 (1) angstrom3 (1453 (2) angstrom3) Z = 4 (4). It has been possible to detect the impurity in 1a by comparing the temperature parameters of the Cl atoms and the residual electron density maps of the final difference Fourier calculations of 1 and 1a. The structure of the [LTiIIICl3] molecule is identical in both 1 and 1a; only slight differences of the packing are observed. Implications of this observation on the "distortional' or "bond stretch" isomerism phenomenon are discussed. Reaction of TiBr4 with L in CH3CN yields [LTiBr3] (2) whereas TiCl4 reacts with L at 20-degrees-C affording [LTiCl3]Cl (5). Complex 1 reacts with CF3SO3H to give blue [LTi(O3SCF3)3] (3) which is a good starting material for the synthesis of complexes containing the LTi(III) fragment. Thus 3 reacts with NaSCN in CH3OH to give [LTiIII(NCS)3] (4). Oxidation of 1 by azide yields [LTiCl2(N3)][BPh4] (6) whereas oxidation of 4 by O2 in the presence of water gives [LTiIV(O)(NCS)2] (7). Crystal data for 7: space group Pna2(1), a = 7.076 (2) angstrom, b = 14.247 (3) angstrom, c = 16.163 (5) angstrom, V = 1629 (2) angstrom3, Z = 4. Complex 7 is the first structurally characterized octahedral complex of titanium(IV) containing a terminal oxo ligand (titanyl group): Ti=O 1.638 (3) angstrom. Air oxidation of 2 in methanol yields [LTiIV(OCH3)Br2](ClO4) (8). Crystal data for 8: space group Pnma, a = 12.819 (3) angstrom, b = 11.608 (2) angstrom, c = 12.686 (3) angstrom, V = 1888 (1) angstrom3, Z = 4. TiCl3 and the ligand L in water containing dimethylformamide form the mu-oxo-bridged dinuclear species [L2TiIII2Cl4(mu-O)) (9) which is oxidized by air to the mixed-valence species [L2Ti2Cl4(mu-O)]Cl.2H2O (10) and, finally, to [L2TiIV2Cl4(mu-O)]Cl2.2.5H2O (11). Complete hydrolysis and air oxidation of 1 in water at pH 7 (NaHCO3) yields colorless crystals of [L2TiIV2(O)2(OH)2(mu-O)].8H2O (12). When the hydrolysis/oxidation reaction of 1 is carried out in a water/nitromethane mixture in the presence of NaF, yellow crystals of [L2Ti2F2(O)2(mu-F)](PF6) (13) were obtained. Crystal data for 13: space group P1BAR, a = 7.676 (5) angstrom, b = 7.695 (6) angstrom, c = 13.67 (1) angstrom, alpha = 75.05 (6)-degrees, beta = 79.67 (6)-degrees, gamma = 70.03 (6)-degrees, V = 729 (1) angstrom3, Z = 1.