The organotin(IV) complexes, ROCOCH 2CH 2SnCl 3 · nL (R = Me, Et, n-Pt, Allyl, n-Bu, i-Bu; n = 1, 2; L = dibutylsulfoxide) have been synthesized and characterized. The spectral data (IR, IH and 13C NMR) indicate that the 1 : 1 ( n = 1) and 1 : 2 ( n = 2) complexes are all hexa-coordinated tin compounds, and the carbonyl oxygen is coordinated to intramolecular tin atom in 1 : 1 complexes and is free in 1 : 2 complexes. The crystal structure of EtOCOCH 2CH 2SnCl 3 · L shows that the tin atom adopts a distorted octahedral geometry via the oxygens of dibutylsulfoxide and intramolecular carbonyl group to tin coordination.