Cis- and trans-[SnR2] configurational isomers in diorganotin(IV) complexes containing mono or bidentate N-donor ligands

The reaction of diorganotin(IV) complexes SnR2Cl2 (R = Et, Ph) with the bidentate pyridyl ligand of 4,4′-di-tert-butyl-2,2′-bipyridine (bu2bpy) or phendione (phendione = 1,10-phenanthroline-5,6-dione) resulted in the formation of the hexa-coordinated 1:1 adducts of [SnR2Cl2(NN] {R = Et, NN = bu2bpy (1); R = Et, NN = phendione (2); R = Ph, NN = bu2bpy (3)}. On the other hand, the reaction of SnPh2Cl2 with the corresponding monodentate ligand of 4-tert-butylpyridine (bupy) affords the 1:2 adduct of [SnPh2Cl2(bupy)2] (4). The solid state X-ray determination of complex [SnEt2Cl2(bu2bpy)] (1) revealed that the complex 1 contains the hexa- coordinated tin(IV) atom in an octahedral geometry with the trans-[SnEt2] configuration while the X-ray crystal structure determination of complex [SnPh2Cl2(bu2bpy)] (3) reveals that the tin atom is hexa-coordinated in a distorted octahedral geometry with an unusual feature of the cis-[SnPh2] configuration. On the other hand, two carbon, two chlorine and two nitrogen atoms from two pyridyl ligands form an octahedral geometry around tin(IV) atom with trans-C2, trans-N2 and trans-Cl2 configurations in [SnMe2Cl2(bupy)2] (5). The resulting products have been fully characterized by elemental analysis, multinuclear NMR (1H, 13C, 119Sn) and 2D NMR (HH- COSY, 1H–13C HMQC) spectroscopy.

Graphical abstractThe reaction of diorganotin(IV) complex of SnR2Cl2 (R = Et, Ph) with the bidentate pyridyl ligand of 4,4′-di-tert-butyl-2,2′-bipyridine (bu2bpy) or phendione (phendione = 1,10-phenanthroline-5,6-dione) results in the formation of [SnR2Cl2(NN)] {R = Et, NN = bu2bpy, phendione; R = Ph, NN = bu2bpy}. In addition, [SnPh2Cl2] reacts with the corresponding monodentate ligand of 4-tert-butylpyridine (bupy) to give the hexa-coordinated 1:2 adduct of [SnR2Cl2(bu2bpy)]. The crystal structures of a related series of diorganotin(IV) complexes of [SnEt2Cl2(bu2bpy)], [SnMe2Cl2(bupy)2] with trans-[SnR2] configuration and [SnPh2Cl2(bu2bpy)] with cis-[SnPh2] configuration are reported. Spectroscopic multinuclear studies were also carried out.Figure optionsDownload full-size imageDownload as PowerPoint slide