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Methylation of [Pt 2 (μ‐SR)(μ‐S)(PPh 3 ) 4 ]: En Route to Mixed‐Thiolato Bridged Complexes
Author(s) -
Chong Siew Huay,
Koh Lip Lin,
Henderson William,
Hor T. S. Andy
Publication year - 2006
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200600060
Subject(s) - chemistry , phosphine , intramolecular force , stereochemistry , steric effects , crystal structure , thio , alkylation , crystallography , catalysis , biochemistry
Abstract Sequential and independent alkylation of [Pt 2 (μ‐S) 2 (PPh 3 ) 4 ] by RX followed by methylation with Me 2 SO 4 led to the first successful isolation of novel diplatinum complexes [Pt 2 (μ‐SR)(μ‐SCH 3 )(PPh 3 ) 4 ](PF 6 ) 2 ( 3 ) (R=CH 2 C 6 H 5 ( a ), CH 2 CHCH 2 ( b ), C 5 H 10 CO 2 CH 2 CH 3 ( c ), C 2 H 4 CO 2 CH 2 CH 3 ( d ), CH 2 CH 2 CN ( e ), C 2 H 4 CH(O) 2 C 2 H 4 ( f ), and C 2 H 4 SC 6 H 5 ( g )) with asymmetric thiolato bridges. The synthetic methodology can tolerate a range of electronically and sterically contrasting thiolate substituents with different chemical functionalities. The X‐ray crystal structures of 3 a–c , g confirm the unusual heterodialkylation with two different thiolato bridging ligands in a syn – exo conformation. A secondary product [Pt 2 (μ‐SC 2 H 4 SC 6 H 5 )(μ‐SCH 3 )(PPh 3 ) 3 ](PF 6 ) 2 ( 4 ), which arises from intramolecular phosphine displacement by the thio pendant at the neighboring SC 2 H 4 SC 6 H 5 bridge, has been trapped and characterized. This is an unusual diplatinum complex with three different bridging thio ligands and three different phosphines. The heteroalkylation is screened in situ by ESI‐MS, and the resultant spectral data provide a convenient guide for one‐pot syntheses of {M 2 (SR)(SR′)} from{M 2 S}. The isolation and X‐ray crystal structure of a homoalkylated analogue [Pt 2 (μ‐SCH 3 ) 2 (PPh 3 ) 4 ](PF 6 ) 2 ( 6 ) is included for comparison.