Cyclodiphosphazane appended with thioether functionality: Synthesis, transition metal chemistry and catalytic application in Suzuki–Miyaura cross-coupling reactions

The coordination chemistry of thioether functionalized cyclodiphosphazane ligand, cis-{tBuNP(OCH2CH2SCH3)}2 (1) is described. The reactions of 1 with [Pd (COD)Cl2] in 1:1, 1:2 and 2:1 M ratios afforded cis-[PdCl2{tBuNP(OCH2CH2SCH3)}2] (2), cis-[{PdCl2}2{tBuNP(OCH2CH2SCH3)}2] (3) and trans-[PdCl2{(tBuNP(OCH2CH2SCH3))2}2] (4), respectively. Treatment of 1 with [Pd(PEt3)Cl2]2 or [PdCl(η3-C3H5)]2 in appropriate molar ratios produce the mono- and binuclear complexes [PdCl2(PEt3{tBuNP(OCH2CH2SCH3)}2] (5) and [{PdCl(η3-C3H5)}2{tBuNP(OCH2CH2SCH3)}2] (6) in good yield. The reaction of 1 with [{Ru(p-cymene)Cl2}2] afforded the mononuclear cationic complex, [{(p-cymene)RuCl{tBuNP(OCH2CH2SCH3)}2]Cl (7), whereas the reactions of [Rh(COD)Cl]2, [Pt(COD)Cl2] and [Au(SMe2)Cl] with 1 yielded the corresponding P-coordinated neutral complexes, [RhCl(COD){tBuNP(OCH2CH2SCH3)}2] (8) cis-[PtCl2{tBuNP(OCH2CH2SCH3)}2] (9), respectively. The binuclear palladium(II) complex 3 was found to be an effective catalyst for the Suzuki–Miyaura cross-coupling reactions.