Synthesis of monoorganotin(IV) chloride complexes of <i>cis</i>-1,2-bis(diphenylphosphino)ethylene: Solution and solid state structures

Organotin(IV) complexes of the type [RSnCl₃ (<i>cis-Ph₂PCH=CHPPh₂</i>)] [R = Me (<b>1</b>), ^<i>n</i>Bu (<b>2</b>), Ph (<b>3</b>)] were prepared by the reaction of RSnCl₃ with the rigid bisphosphine ligand, <i>cis</i>-1,2-bis(diphenylphosphino)ethylene in dichloromethane. The complexes have been characterized both in solution and the solid state. Low temperature ³¹P and ¹¹⁹Sn NMR studies indicate two different phosphorus environments. The crystal structures indicate a weak but chelating mode of coordination of the two phosphorus atoms to tin, leading to a distorted octahedral geometry. In solution the complexes <b>1–3</b> undergo a redistribution reaction to form [SnCl₄ (<i>cis-Ph₂PCH=CHPPh₂</i>)] (<b>4</b>) as one of the products. In order to confirm the redistribution, complex <b>4</b> has been prepared separately and characterized both structurally and spectrally.