SYNTHESIS, CHARACTERIZATION AND SPECTROSCOPIC INVESTIGATIONS OF TIN(IV) AND ORGANOTIN(IV) DERIVATIVES OF 4-AROYL-5-PYRAZOLONES - CRYSTAL-STRUCTURE OF -METHYL-4-(4-BROMOBENZOYL)-PYRAZOLON-5-ATO]TIN(IV)

Stable six-coordinate derivatives [(Q)2SnRX] [QH is 1-phenyl-3-methyl- 4-R'C(=O)-pyrazol-5-one (R' = 4-BrC6H4 {Q(Br)H}, 4-FC6H4 {Q(F)H}, 4-Cl C6H4 {Q(Cl)H}, 4-IC6H4{Q1H}, or 4-C7H15-C6H4 {Q(R)H}), X = Cl or R, an d R = Cl, Me, (n)Bu, (t)Bu, Ph, vinyl or benzyl] and 1:1 adducts [(QH) SnR(n)X4-n].xS [QH = 1-phenyl-3-methyl-4-R'C(=O)-pyrazol-5-one (R' = 4 -BrC6H4, 4-FC6H4 or 4-C7H15-C6H4; X = Cl or R and R = Cl, Me, or Ph; x = 0, 1/2, or 1; S = CH2Cl2, H2O, or Et2O] have been synthesized and c haracterized by analysis and spectral (IR, and H-1, C-13, and Sn-119 N MR) data. The diffraction study of the complex [(Q(Br))2SnMe2] shows t he metal to be six-coordinate in a skewed trapezoidal bipyramidal (STB -6) geometry; Sn-O distances are 2.104(4) and 2.099(4) angstrom, and 2 .385(5) and 2.436(5) angstrom and the Me-Sn-Me bond angle is 154.5(3)- degrees. In Q(Br), 4-bromophenyl and the pyrazolone rings are nearly c oplanar. This co-planarity is opposed by an intramolecular repulsive f orce between one ortho H atom of the bromophenyl moiety and one O atom of the chelate ring. This feature appears related to the small bite o f the ligand Q(Br) (O-Sn-O bond angles of 78.5(2)-degrees and 79.5(2)- degrees which may be responsible for the STB-6 geometry.