Preparation and spectroscopic studies of five-co-ordinate β-diketonatotri(organo)tin compounds. Crystal structure of (1,3-diphenylpropane-1,3-dionato)triphenyltin(IV)

Abstract

A series of new five-co-ordinate complexes, R₃SnL [R = Me. (I)–(III) or Ph, (IV)–(VI); L = anions of acetylacetone (acac), benzoylacetone (bzac), or dibenzoylmethane (bzbz)], has been prepared and characterized by i.r., n.m.r. and Mössbauer spectroscopy. Compounds (I)–(III) have large quadrupole splittings (3·69–3·86 mm s^–1), while those of (IV)–(VI) are much smaller (1·38–2·25 mm s^–1). By use of partial quadrupole splittings these splittings are shown to be consistent with the mer-structure for compounds (I)–(III), and the all-cis-structure for (IV)–(VI). The all-cis-structure has been confirmed for (VI), [Ph₃Sn(bzbz)], by a single-crystal X-ray diffraction study. Crystals are monoclinic, space group P2₁/c, with Z= 4 in a unit cell of dimensions: a= 13·216(5), b= 9·443(4), c= 22·344(9)Å, and β= 109·42(2)°. The structure was solved by the heavy-atom method from intensity data collected by diffractometric methods, and refined by full-matrix least-squares methods to R 0·051 for 2328 observed reflections. The co-ordination about the Sn atom is essentially a distorted trigonal bipyramid. The phenyl groups occupy one axial and two equatorial co-ordination sites with the chelating ligand bonded to one equatorial and one axial site. Sn–C(eq) Bond lengths are 2·149(7) and 2·181(6), and Sn–C(ax) 2·180(6)Å. The Sn–O(ax) distance [2·276(7)Å] is significantly longer than Sn–O(eq)[2·094(7)Å].