Methylation of [Pt2(mu-SR)(mu-S)(PPh3)4]: en route to mixed-thiolato bridged complexes.
Sequential and independent alkylation of [Pt2(mu-S)2(PPh3)4] by RX followed by methylation with Me2SO4 led to the first successful isolation of novel diplatinum complexes [Pt2(mu-SR)(mu-SCH3)(PPh3)4](PF6)2 (3) (R = CH2C6H5 (a), CH2CHCH2 (b), C5H10CO2CH2CH3 (c), C2H4CO2CH2CH3 (d), CH2CH2CN (e), C2H4CH(O)2C2H4 (f), and C2H4SC6H5 (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 [Pt2(mu-SC2H4SC6H5)(mu-SCH3)(PPh3)3](PF6)2 (4), which arises from intramolecular phosphine displacement by the thio pendant at the neighboring SC2H4SC6H5 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 {M2(SR)(SR')} from{M2S}. The isolation and X-ray crystal structure of a homoalkylated analogue [Pt2(mu-SCH3)2(PPh3)4](PF6)2 (6) is included for comparison.
Chong
Siew Huay
SH
Department of Chemistry, National University of Singapore, 3, Science Drive 3, Singapore, Singapore.
Koh
Lip Lin
LL
Henderson
William
W
Hor
T S Andy
TS