Tin(IV) and organotin(IV) derivatives of novel β-diketones: II. Mono- and diaryltin(IV) complexes of 1-phenyl-3-methyl-4-R(CO)-pyrazol-5-one (R=CCl3, OCH3, OC2H5). Crystal and molecular structure of trans-dibenzylbis(1-phenyl-3-methyl-4-methoxycarbonyl-pyrazolon-5-ato)tin(IV), (C7H7)2Sn(QOMe)2

Abstract A series of new tin(IV) and organotin(IV) derivatives has been synthesized. In basic (triethylamine) chloroform solution five- [R 2 SnCl(Q * )] and six-coordinate [R 2 Sn(Q * ) 2 ] tin(IV) derivatives (HQ * =1-phenyl-3-methyl-4-trichloroacetylpyrazol-5-one; R=Ph, Bz) are obtained. In basic (KOH) alcoholic R′OH solution (R′=Me, Et) [R 2 Sn( Q O R ′ ) 2 ] and [RSnCl 2 ( Q O R ′ )] derivatives (Q OR =1-phenyl-3-methyl-4-alkoxycarbonyl-pyrazolon-5-ato) are obtained, upon cleavage of the C–CCl 3 bond in the starting HQ * donor. From interaction between HQ * and SnCl 4 in refluxing dichloromethane the adduct SnCl 4 (HQ * ) was isolated. Additionally the donor HQ * reacts with RSnCl 3 (R=Ph, Bu n ) in basic (triethylamine) tetrachloromethane solution to form the salt-like products [Et 3 NH] + [RSnCl 3 (Q * )] − . All the compounds were characterized by analytical and spectral (IR, far-IR, 1 H, 13 C and 119 Sn NMR) data. The diffraction study of the complex Bz 2 Sn(Q OMe ) 2 shows a six-coordinate tin in a distorted octahedral frame, with the Bz groups trans to each other. The Bz–Sn–Bz bond angle is 164.5(4)° and the Sn–O distances are 2.105(6) and 2.359(7) A in one ligand and 2.109(7) and 2.329(7) A in the other. We find that in bis(pyrazolonate)diorganotin complexes structural features such as bite angle, difference of Sn–O bond length and O–Sn–O bond angles are functions of the organometallic C–Sn–C bond angle.