First heterodifunctional ligand derived from a tetradentate phosphine: synthesis and characterization of cis, trans,cis-1,3-bis(diphenylphosphino) 2,4-bis(diphenylphosphinothioyl) cyclobutane and its complex with PdCl2

Cis,trans,cis-1,2,3,4-tetrakis(diphenylphosphino)cyclobutane (dppcb) can be selectively oxidized by S in toluene to the disulfide cis,trans,cis-1,3-bi s(diphenylphosphino)-2,4-bis(diphenylphosphinothioyl)cyclobutane (dppcbS(2) ). DppcbS(2) is the first heterodifunctional ligand derived from a tetraden tate phosphine obtained with good yield and high purity. It reacts with two equivalents of PdCl2 producing [Pd2Cl4(dppcbS(2))] (1). Both dppcbS(2) and 1 have been fully characterized by X-ray structure analyses, NMR spectrosc opy (P-31{H-1}, C-13{H-1}, H-1), FAB mass spectrometry, elemental analyses and melting points. The possible catalytic applications of the versatile he terodifunctional ligand dppcbS(2) are discussed in view of the two X-ray st ructures of dppcbS(2) and 1. (C) 2000 Elsevier Science S.A. All rights rese rved.