Synthesis and Characterization of Diorganotin Compounds {[R2Sn（ON=CHC6H5）]2O}2 and Crystal Structure of {[（C6H5CH2）2Sn（ON=CHC6H5）]2O}2

Diorganotin compounds {[R2Sn(ON=CHC6H5)]2O}2 [R=C6H5CH2 (1), 2-FC6H4CH2 (2), 4-FC6H4CH2 (3), 2-ClC6H4CH2 (4), 4-ClC6H4CH2 (5)] were synthesized by the reaction of R2SnO with HON=CHC6H5 in 1∶1 mo-lar ratio in refluxing anhydrous benzene or toluene. They were characterized by elemental analysis, IR, 1H NMR and 119Sn NMR spectroscopy. And two sets of 119Sn chemical shifts were observed in the 119Sn NMR spectra of these compounds, indicating the presence of two types of environment around the tin atoms. The crystal structure of compound 1 was determined by X-ray single crystal diffraction analysis. The results showed that the crystal of com-pound 1 belongs to a monoclinic system with space group P21/c and unit cell dimensions: a=1.0718(9) nm, b=1.9666(17) nm, c=2.0480(17) nm, =96.4371(14)? Dc=1.450 g/cm3, Z=2, F(000)=1888, V=4.290(6) nm3, =1.206 mm-1, R1=0.0405, wR2=0.0786. The compound 1 belongs to centrosymmetric dimer structure mode with a four-membered central endo-cyclic Sn2O2 unit in which the bridging oxygen atoms are tri-coordinated. Each bridging oxygen atom also connects with an exo-cyclic tin atom. The endo- and exo-cyclic tin atoms are both five-coordinated, and have coordination geometry of distorted trigonal bipyramid.