Triorganotin(IV) derivatives of several 4-acyl-5-pyrazolonato ligands: synthesis, spectroscopic characterization and behavior in solution Crystal structure of aquotrimethyl(4-p-methoxybenzoyl-1-phenyl-3-methyl-pyrazolon-5-ato)tin(IV)

New triorganotin(IV) derivatives [(Q)SnR3 · x(H2O)] (x = 0, R ? Ph; x = 1, R ? Me and nBu) (in general QH ? 1-R?-3-methyl-4-R? (C?C)-pyrazol-5-one; in detail Q?H: R? = C6H5, R? = C6H5; QAH:R? = C6H5, R? = p-CH3O?C6H4; QNH: R? ?C6H5, R? ? p-NO2?C6H4; QBrH:R? = C6H5, R? = p -Br?C6H4; Q?H: R? = C6H5,R? = CH3; QClH: R? = C6H5, R? = CCl3; QFH: R? = C6H5, R? = CF3; QMH: R? = CH3 R? = C6H5; QDH: R? = CH3, R? = CH3) have been synthesized and characterized by analysis and spectral (IR and 1H, 13C and 119Sn NMR) data. The (Q)SnPh3 derivatives are five-coordinated in the solid state, with a likely skewed cis-trigonal bipyramidal (cis-TBP) geometry around the tin center and the ligand (Q)- acting in the bidentate form. In [(Q)SnR3 · (H2O)] derivatives (R = nBu or Me) a coordination site is occupied by water, with the ligand (Q)- coordinating in a monodentate fashion. The crystal structure of [(QASnMe3 · (H2O)] has been determined: the tin atom is found in a distorted TBP environment, with the methyl in the equatorial positions. Two of the Sn?C bond lengths are normal (2.11(1) and 2.08(2) Å) whereas the third is longer (2.18(2) Å); the ligand binds the metal atom through one carbonyl oxygen in the apical position (Sn?O = 2.10(1) Å). The bond lenght between H2O and Sn is longer (2.41(2) Å), and the O?Sn?O angle is 174.9(5)°. H atoms of water are involved in an intermolecular H-bond network with uncoordinated carbonyl and the pyridinic N atom of the ligand. In chloroform solution the[(Q)Snr3 · (H2O)] derivatives (R = Me or nBu) lost the molecule of water and adopt a tetrahedral arrangement. They also give rise to a slow disproportionation, yielding SnR4 and [(Q)2SnR2] derivatives.