Synthesis, spectroscopic characterization of bis-[oxo-bis(4-ferrocenylbenzoato dialkyltin (IV))] and crystal structural studies of the former compound

In this paper; the novel compounds {[(n-Bu)(2)Sn(4-Fc-C6H4COO)](2)O}(2) (1) and {[(n-Oct)(2)Sn(4-Fc-C6H4COO)](2)O}(2) (2) (Fc = ferrocenyl) have been synthesized and characterized by elemental analysis, IR and NMR (H-1, C-13 and Sn-119) spectroscopy. The crystal structure of compound 1 has been dete rmined by single crystal X-ray diffraction techniques. The crystal belongs to monoclinic with space group P2(1)/c. The cell parameters are: a = 1.298 8(1) nm, b = 2.465 5(1) nm, c = 3. 450 6 (1) nm, beta = 91.556(2)degrees, V = 11. 045 4(1) nm(3), Z = 4. The structure was refined to final R-f = 0.07 1, R-w = 0.074. Compound 1 is a dimer structure mode with a four-member cen tral endo-cyclic Sn2O2 unit in which the bridged oxygen atoms are tri-coord inated. Each bridged oxygen atom also connects an exo-cyclic tin atom. Both endo- and exo-cyclic tin atoms are all five-coordination and have coordina tion geometry of monocapped trigonal bipyramid with very similarly distorte d mode. Four carboxylate ligands are divided into two types. Two of the car boxylate ligands are bidentate and bridging to each pair of exo- and endocy clic tin atoms by using both oxygen atoms. The others are monodentate and c oordinate each exo-cyclic tin atom. When considering further the longer dis tance interactions between the carboxyl oxygen in carboxylate ligand and en do-cyclic tin atom (0. 277 5-0. 286 6 nm) and between the ester oxygen in c arboxylate ligand and exo-cyclic tin atom (0. 298 0-0. 300 6 nm), not only carboxylate ligand chelates to exo-cyclic tin by anisobidentate mode but al so their eater oxygen itself is tricoordinated and bridges to both endo- an d exo-cyclic tin atoms. In compound 1, the coplanarity of two conjugate sys tems (benzoyloxy group and substituted Cp ring) is not good. And two conjug ate systems can not be coplanar with the central endo-cyclic Sn2O2 unit. Un like the general compounds characteristic of {[R2Sn(O2CR')](2)O}(2), there is no center of symmetry in the molecule structure of compound 1.