Synthesis and characterisation of homo- and hetero-trinuclear complexes containing the triply-bridging diphenylthiophosphinito [µ3-SPPh2]– ligand: molecular structure of [Pd3(µ3-SPPh2)2(C6F5)2(C6H4CH2NMe2-2)(PPh3)2]ClO4·0.8CH2Cl2

Abstract

The dinuclear complex [{Pd(µ-SPPh₂)(C₆F₅)(PPh₃)}₂] reacted with the cationic precursors [PdL(Me₂CO)₂]⁺[L = 2-(dimethylaminomethyl)phenyl-C¹,N, quinolin-8-ylmethyl-C,N or phenylazophenyl-C¹,N] and with the neutral precursors [M(C₆F₅)₂(thf)₂](M = Pd or Pt, thf = tetrahydrofuran) to give the corresponding cationic homotrinuclear complexes [Pd₃(µ₃-SPPh₂)₂(C₆F₅)₂L(PPh₃)₂]ClO₄(L = C₆H₄CH₂NMe₂-2 1, NC₉H₆CH₂-8 2 or PhNNC₆H₄3) and the neutral homo- and hetero-trinuclear complexes [Pd₂M(µ₃-SPPh₂)₂(C₆F₅)₄(PPh₃)₂](M = Pd 4 or Pt 5) in which the [SPPh₂]^– group acts as a triply-bridging ligand. Complexes 1–5 have been characterized by spectroscopic methods (IR; ¹H, ¹⁹F and ³¹P-{¹H} NMR) and the molecular structure of [Pd₃(µ₃-SPPh₂)₂(C₆F₅)₂(C₆H₄CH₂NMe₂–2)(PPh₃)₂]ClO₄1 has been determined crystallographically. Complex 1·0.8CH₂Cl₂ crystallizes in the monoclinic system, space group P2₁/c, a= 14.185(3), b= 21.589(4), c= 27.440(5)Å, β= 104.95(3)° and Z= 4. The model refined to final values of R= 0.0702 and R′= 0.0849 for 5989 observed reflections [F > 4.0σ(F)] and 860 parameters. The structure shows that the [Pd(µ-SPPh₂)(C₆F₅)(PPh₃)]₂ unit behaves as a cyclic bidentate sulfur ligand, co-ordinated to the [Pd(C₆H₄CH₂NMe₂-2)]⁺ group through the two S atoms. The central Pd₃(SPPh₂)₂ cage contains two µ₃-SPPh₂ ligands linking the three palladium atoms.