Preparation and tin-119m Moessbauer spectra of diorganotin(IV) complexes of picolinic acid and picolinic acid N-oxide

Article abstract of DOI:10.1016/0022-328X(91)86008-E

Two types of complexes of diorganotin picolinates (i) R2Sn(Pic)2 <2:1> and (ii) 2O <1:1> and of diorganotinpicolinate N-oxides (i) R2Sn(PicO)2 <2:1> and (ii) 2O <1:1> (R = CH3, n-C4H9, n-C8H17, C6H5CH2) have been prepared by reacting picolinic acid and picolinic acid N-oxide with diorganotin oxide in 2:1 and 1:1 ligand:metal molar ratio.The methyl and benzyl derivatives are less soluble in organic solvents whereas the butyl and octyl derivatives are more soluble.A unidentate carboxylate is present in all the complexes.However, a weak interaction such as C=O -> Sn cannot be ruled out in the less soluble complexes.In the picolinates the ring nitrogen coordinates to tin(IV) intramolecularly in the butyl and octyl derivatives and intra- and intermolecularly in the ethyl and benzyl derivatives.Moessbauer parameters show a distorted trans octahedral structure for the 2:1 derivatives and a distorted trans trigonal bipyramidal structure for the 1:1 picolinates with an Sn-O-Sn bridge.A mixed distorted trans octahedral tin atom geometry and a distorted trans trigonal bipyramidal tin with an Sn-O-Sn bridge are found in the same molecule in the 1:1 complexes of picolinic acid N-oxide.