Novel binuclear diorganotin(IV) complexes of adipic acid dihydrazone containing flexible aliphatic spacer: X-ray structural characterization of dimethyltin(IV) complex

Abstract

Three novel binuclear diorganotin(IV) derivatives formulated as (R2Sn)2L (where R = Me, Bu and Ph) of a new symmetrical adipodihyrazone ligand, 1,6-bis(5-hydroxy-3-methyl-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl)hexane-1,6-dione (H4L) derived from the Schiff base condensation of adipic acid dihydrazide and benzoylacetone in a 1:2 M ratio were synthesized. The micro-analysis and various spectroscopic techniques viz., infrared (IR), multinuclear (1H, 13C and 119Sn) magnetic resonance (NMR) spectroscopy and electrospray ionization mass (ESMS) spectrometry were employed to establish the chelating mode of the dihyrazone ligand towards the diorganotin moieties [R2Sn(IV)]2+. The single crystal X-ray diffraction analysis of complex, (Me2Sn)2L reveals that it crystallizes in monoclinic space group ‘P 21/n’ and consists of crystallographically discrete molecules. The complex has been investigated to prefer a highly distorted trigonal-bipyramidal geometry (TBP) over the square-pyramidal geometry (SP) around each tin centre wherein the more electronegative enolic and benzoylic oxygen atoms of the ligand are aligned axially, and two carbon atoms of the methyl groups attached to the tin metal atom and the imine nitrogen atom of the ligand aligned themselves equatorially around the tin centre in a trigonal plane. Thermal decomposition patterns of the dimethyl- and diphenyltin(IV) derivatives in air were also investigated by TG, DTG and DTA techniques.