A DIPOLE MOMENT STUDY OF 6-COORDINATE ORGANOTIN CHELATE COMPOUNDS

Diphenyl-, dimethyl-, diethyl-, and dibutyltin acetylacetonates, dibenzoylmethanates, and hexafluoroacetylacetonates have been synthesized, and their structures have been studied in benzene and cyclohexane solutions. Polarization measurements obtained at several temperatures show that the complexes possess orientation dipole moments of 2.0-4.0 D. It appears likely that the molecules possess structures of the cis-octahedral type with most exhibiting some distortion from the regular geometry. The distortion appears to vary regularly with the electronegativities of the organic substituents. Supplementary infrared, ultraviolet, and nmr data, respectively, are consistent with the assumptions (1) that the complexes are sixcoordinate, (2) that tin-oxygen bonds are of a simple polar type lacking (p → d)π character, and (3) that exchange is very rapid at room temperature for the β-ketoenolate groups. © 1969, American Chemical Society. All rights reserved.