Synthesis and characerization of di-n-butyltin(IV) complexes with 4'/2'-nitrobiphenyl-2-carboxylic acids: X-ray crystal structures of [{n-C_4H_9)_2Sn(OCOC_(12)H_8NO_2-4')}_2O]_2 and (n-C_4H_9)_2Sn{OCOC_(12)H_8NO_2-4'}_2

摘要

Reactions of di-n-butyltin(IV) oxide with 4'/2'-nitrobiphenyl-2-carboxylic acids in 1:1 and 1:2 stochiometry yield complexes [{n-C_4H_9}_2Sn(OCOC_(12)H_8NO_2-4')]_2O]_2 (1 and 2) and (n-C_4H_9)_2Sn{OCOC_(12)H_8NO_2-4'}_2 (3 and 4) respectively. These compounds were characterized by elemental analysis, IR and NMR (~1H, ~(13)C and ~(119)Sn)_ spectroscopy. The IR spectra of these compounds indicate the presence of anisobidentate carboxylate groups and non-linear C-Sn-C bonds. From the chemical shifts delta (~(119)Sn) and the coupling constants ~1J(~(13)C, ~(119)Sn), the coordination number of the tin atom and the geometry of its coordination sphere have been suggested. [{n-C_4H_9}_2Sn(OCOC_(12)H_8NO_2-4')]_2O]_2 (1) exhibits a dimeric structure containing distannoxane units with two types of tin atom with essentially identical geometry. To a first approximation, the tin atoms appear to be pentacoordinated with distorted trigonal bipyramidal geometry. However, each type of tin atom is further subjected to a sixth weaker interaction and may be described as having a capped trigonal bipyramidal structure the diffraction study of the complex (n-C_4H_9)_2Sn{OCOC_(12)H_8NO_2-4'}_2 (3) shows a si-coordiante tin in a distorted octahedral frame containing bidentate asymmetric chelating carboxylate groups, with the n-Bu groups trans to each other. The n-Bu-Sn-n-Bu angle is 152.8 deg and the Sn-O distances are 2.108(4) and 2.493(5) A. The oxygen atom of the nitro group of the ligand does not participate in bonding to the tin atom in 1 and 3. Crystals of 1 are triclinic with space group P1 and of that of 3 have orthorhombic space group Pnna.