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

Abstract

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