Coordination of a hemilabile pincer ligand with an olefinic backbone to mid-to-late transition metals

Abstract

The coordination chemistry of a neutral tPCH=CHP pincer (tPCH=CHP = 2,2′-bis(di-iso-propylphosphino)-trans-stilbene) with metals that form stable complexes in the +1 oxidation state was studied and (tPCH=CHP)CoCl, (tPCH=CHP)CoCl(CO), (tPCH=CHP)RhCl, (tPCH=CHP)Cu(OTf), [(tPCH=CHP)Cu][PF 6], and [(tPCH=CHP)Ag][PF6] were synthesized and characterized. In order to determine whether the coordination mode is dependent on the oxidation state of the metal, some +2 metal complexes, (tPCH=CHP)CoCl2 and (tPCH=CHP)FeBr2, were also investigated. The coordination of the olefinic backbone is not observed in (tPCH=CHP)FeBr2, (tPCH=CHP)CoCl2, (tPCH=CHP)Cu(OTf), or [(tPCH=CHP)Ag][PF6], but 2-coordination is present in [(tPCH=CHP)CoCl][BArF4], [(tPCH=CHP)FeBr][BAr F4], (tPCH=CHP)CoCl, (tPCH=CHP)CoCl(CO), (tPCH=CHP)RhCl, and [(tPCH=CHP)Cu][PF6]. Cobalt(II), iron(II), and copper(I) formed complexes with the ligand in both coordination modes. All metal complexes were characterized by multinuclei NMR spectroscopy, X-ray crystallography, and elemental analysis. © 2014 American Chemical Society.