A tetraphosphino-bis(s-triazine) from cyanuric chloride and Ph2PH: new unexpected tandem C–C/C–P coupling reaction

Abstract

Serendipitous synthesis of 4,4′,6,6′-tetrakis(diphenylphosphino)-2,2′-bi(s-triazine) (Tr₂P₄) – a novel promising polyphosphine ligand – from cyanuric chloride and diphenylphosphine is reported. This unusual reaction represents the first example of tandem C–C/C–P coupling between (het)aryl halides and P–H species, yielding a structurally unique bi(hetaryl)-tetraphosphine. Theoretical study indicates that the 2,2′-bi(s-triazine) core arises from hydrolysis of an intermediate [Ph₂P(TrCl₂)₂]⁺ salt, formed through quaternization of monophosphine Tr(PPh₂)Cl₂ with cyanuric chloride. The structure and photoluminescent properties of Tr₂P₄ were studied. Its coordination chemistry was further demonstrated through the synthesis of tetranuclear Au(I) and Pd(II) complexes, along with the corresponding tetraphosphineselenide. The Au(I) complex exhibited distinct orange-to-green thermochromic luminescence upon cooling-warming in the 77–298 K range.