Reaction of a heterotopic P,SAs ligand with group 10 metal(ii) complexes: As–S bond cleavage and the formation of two unusual trinuclear structural isomers for Pd and Pt

Abstract

The synthesis of the heterotopic P,SAs ligand, 1-Ph(2)AsSC(6)H(4)-2-PPh(2) (1) and its reaction with [PdCl(2)(cod)], [PtI(2)(cod)] (cod = 1,5-cyclooctadiene) and NiCl(2)·6H(2)O is reported. Cleavage of the As-S bond of 1 and coordination of the resulting phosphanylthiolato ligand (SC(6)H(4)-2-PPh(2))(-) (SC(6)H(4)-2-PPh(2) = P,S) was observed with formation of [M(P,S)(2)] (M = Ni, Pd, Pt). In the case of Pd and Pt, not only the mononuclear complexes [M(P,S)(2)] formed, but also the trimers of [MX(P,S)] ([MX{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}](3) [M = Pd, X = Cl (2) and M = Pt, X = I (4)]). Formation of 2 and 4 was preceded by the trinuclear isomeric intermediates [(cis-M{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}(2))-MX(2)-MX{(μ-S-SC(6)H(4)-2-PPh(2))-κ(2)S,P}] [M = Pd, X = Cl (3) and M = Pt, X = I (5)]. The crystal structures of 1-5 and a possible reaction mechanism that leads to 2 and 4 are presented.

Structural Preferences in Phosphanylthiolato Platinum(II) Complexes

“…Concerning the mechanism of the reaction, as we have observed in this work, the 31 P{ 1 H} NMR of the reaction mixture of one equivalent of the phosphanylarylthioarsine Ph 2 AsSC 6 H 4 ‐2‐PPh 2 with [PtI 2 (COD)] shows initially the existence of a mixture of the bis‐chelate and a second complex with chemical displacement at lower frequencies and larger 1 J P−Pt coupling constant. The second compound resulted to be the trinuclear [PtI(μ‐SC 6 H 4 ‐2‐PPh 2 ‐κ 2 P , S )] 3 . This parallelism, and the crystal structure obtained, allow us to assign the major component of our reaction mixture to complex 2 .…”

“…This cycle adopts a skew‐boat conformation (Figure ) with each bridging sulfur atom showing one shorter and one longer Pt−S bond (Figure ). Similar unsymmetrical bridging sulfurs were observed in related compounds . The S−Pt−S angles are smaller than Pt−S−Pt ones because of the restriction imposed by the metal square‐planar coordination.…”

“…The crystal structure reveals a sulfur‐bridging edge‐sharing cyclic trinuclear complex with square‐planar coordination geometry around the platinum atoms (Figure ). Related structures were found for aminoalkylthiolato, [PtBr(μ‐SCH 2 CH 2 NMe 2 ‐κ 2 N , S )] 3 , phosphanylarylthiolato, [PtI(μ‐SC 6 H 4 ‐2‐PPh 2 ‐κ 2 P , S )] 3 and [PtI{μ‐SC 6 H 4 ‐2‐P(1,1′‐biphenyl)‐κ 2 P , S }] 3, and arsanylarylthiolato ligands, [PtI(μ‐SC 6 H 4 ‐2‐PAs 2 ‐κ 2 As , S )] 3 , but complex 2 is, to our knowledge, the first example with phosphanylalkylthiolato ligand.…”

Synthesis and coordination chemistry of thiophenol-based heterodonor ligands containing P,S, As,S and P,SAs donor atoms

“…The isomerisation process was observed by 31 P{ 1 H} NMR spectroscopy; all the structural isomers were isolated and characterised by X-ray structure analysis. In contrast, the reaction of P,SAs with NiCl 2 •6H 2 O led only to the bis-chelate complex, trans-[Ni{(PS)κ 2 S,P} 2 ] [142].…”

“…The synthesis of P,SAs starts with the ortho-lithiation of the thiophenol followed by reaction with Ph 2 PCl. The monolithiation of the resulting phosphanylarylthiol PSH allowed introduction of the third donor group through reaction with Ph 2 AsCl (Scheme 27) [142].…”