Structure-reactivity studies of chloro and isothiocyanato diorganotin (IV) complexes based on multidentate N-donor ligands: Synthesis, spectral characterization and crystal structures

The reaction of [SnMe2Cl2] with the bidentate ligand 4,7-phenanthroline (4,7-phen) resulted in the formation of [SnMe2Cl2 (4,7-phen)](n) (1a) which is probably a polymeric chain in solution. On the other hand, the reaction of [SnEt2Cl2] with 4,7-phen afforded the complex [Sn2Et4Cl4 (kappa(1)-N-4,7-phen)(2)(mu-kappa(2)-N,N-4,7-phen)] (1b) which dissociates in dimethylsulfoxide solution. The reaction of [SnR2Cl2] (R = Me, Et) with 2,2'-biquinoline (biq) yielded the complexes [SnMe2Cl2 (kappa(2)-N,N-biq)] (2a) and [SnEt2Cl2 (kappa(1)-N-biq)(2)] (2b) in the solid state. Moreover, the reaction of [SnR2Cl2] (R = Me, Et) with the tridentate ligand 4'-(2-furyl)-2,2':6',2 ''-terpyridine (ftpy) resulted in the formation of ionic penta- and hexa-coordinated tin complexes [SnMe2Cl (ftpy)][SnMe2Cl3] (3a) and [SnEt2Cl (ftpy)]Cl (3b). The reaction of [SnMe2 (NCS)(2)] with ftpy afforded the hepta-coordinated complex [SnMe2 (NCS)(2)(ftpy)] (4a). The products were fully characterized using elemental analysis, and infrared, UV-visible, multinuclear (H-1, C-13, Sn-119) NMR, DEPT-135 degrees, HH-COSY and HSQC NMR spectroscopies. The crystal structure of complex 3a reveals that it contains the simultaneous presence of penta- and hexa-coordinated tin (IV) atoms. Notably, the crystal structure of complex 4a shows that tin (IV) is hepta-coordinated in a pentagonal bipyramidal geometry SnC2N5 by three nitrogen atoms of ftpy, two nitrogen atoms of NCS- and two Me groups with trans-[SnMe2] configuration. These data indicate the influence of halide or pseudo-halide group on the coordination number and geometry of tin. Hirshfeld surface analysis and two-dimensional fingerprint plots were calculated for 3a and 4a which show the pi-pi interaction between molecules in the solid is relatively weak.