Interaction of ethyltrichlorostannane with N,N-dimethylamides of O- trimethylsilyl-α-hydroxyacids

Reactions of ethyltrichlorostannane with N,N‐dimethylamides of 2‐(trimethylsilyl)glycolic (2a), 2(S)‐lactic [(S)‐2b] and mandelic (2c) acids led to the first representatives of tin(IV) O,O‐monochelates containing the five‐membered SnOCC(O) monoanionic chelate cycles as a result of the substitution of one halogen atom. According to the X‐ray data, in the case of the derivatives of glycolic and mandelic acids, the isolated complexes have dimeric structures {EtCl2Sn[OCH(R)C(O)NMe2]}2 [R = H (3a), Ph (3c)] with the bridge oxygen atoms and hexacoordinated tin atoms. By contrast, in the case of the derivative of lactic acid (S)‐2b, the product of the reaction is the cationic–anionic complex 2EtCl2Sn[OCH(Me)C(O)NMe2]·HCl (4), which is the adduct of two molecules of the respective monomeric complex with HCl. In addition, N,N‐dimethylamide of O‐triethylstannylglycolic acid (5) with tetracoordinated tin is described. To analyze the stability of complex 4, the experimental charge density study and the quantum chemical calculations [PBE0/6‐311G(d,p)] were carried out. Topological analysis of the experimental and calculated electron density distribution functions allowed us to conclude that the strong OH···O bond with pronounced covalent contribution stabilizes the dimeric structure of 4 to a greater extent than the bridged SnCl bonds. Copyright © 2010 John Wiley & Sons, Ltd. Reactions of EtSnCl3 with N,N‐dimethylamides of 2‐(trimethylsilyl)glycolic, 2(S)‐lactic and mandelic acids led to the tin(IV) O,O‐monochelates containing the five‐membered SnOCC(O) monoanionic chelate cycles as the result of substitution of one halogen atom. Hexacoordination of tin atom was confirmed by the X‐ray diffraction and 119Sn NMR studies. Chemical bonding in the dimeric complex with mandelic acid stabilized by strong intramolecular OH···O bond was studied from the results of experimental charge density analysis and quantum chemical calculations.