a b s t r a c tAlkylation reactions of the nucleophilic platinum(II) sulfide complex [Pt 2 (l-S) 2 (PPh 3 ) 4 ] with functionalised alkylating agents have been investigated as a versatile synthetic route to dinuclear, cationic sulfidethiolate complexes of the type [Pt 2 (l-S)(l-SR)(PPh 3 ) 4 ] + , extending the range of thiolate complexes that can be prepared using this methodology. A wide range of functional groups can be incorporated, using appropriate alkylating agents, and include ketone, ester, amide, hydrazone, semicarbazone, thiosemicarbazone, oxime, guanidine, urea and thiourea groups.
The cationic monoalkylated derivatives of the well-known metalloligand [Pt 2 (-S) 2 (PPh 3) 4 ], viz. [Pt 2 (-S)(-SR)(PPh 3) 4 ] + (R = n-Bu, CH 2 Ph) are themselves able to act as metalloligands towards the Ph 3 PAu + and R'Hg + (R' = Ph or ferrocenyl) fragments, by reaction with Ph 3 PAuCl or R'HgCl respectively. The resulting dicationic products [Pt 2 (-2 SR)(-SAuPPh 3)(PPh 3) 4 ] 2+ and [Pt 2 (-SR)(-SHgR')(PPh 3) 4 ] 2+ are readily isolated as their hexafluorophosphate salts, and have been fully characterised by spectroscopic techniques and an X-ray structure determination on [Pt 2 (-SR)(-SHgFc)(PPh 3) 4 ](PF 6) 2 .
The reactivity of the metalloligand [Pt2(micro-S)2(PPh3)4] towards a variety of copper(II)-ligand systems has been studied. Reaction of [Pt2(mu-S)2(PPh3)4] with copper(II) halide complexes [CuCl2L](L = 2,2'-bipyridine and 1,10-phenanthroline) gave trinuclear dicationic products [Pt2(mu-S)2(PPh3)4CuL]2+, and the 8-hydroxyquinolinate (hq) complex [Cu(hq)2] gave [Pt2(mu-S)2(PPh3)4Cu(hq)]+, isolated as their BPh4- or PF6- salts. Related cationic complexes with other ancillary amine ligands (1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminocyclohexane) were obtained by reactions of [Pt2(mu-S)2(PPh3)4] with CuCl2 and the amine. In contrast, reaction of [Pt2(mu-S)2(PPh3)4] with CuCl2 and NH3 in methanol gave the intensely blue methoxy-bridged dicopper complex [{Pt(2)(mu-S)2(PPh3)4Cu(OMe)}2]2+, isolated as its hexafluorophosphate salt. Copper beta-diketonate complexes reacted with [Pt2(mu-S)2(PPh3)4] giving [Pt2(mu-S)2(PPh3)4Cu(beta-diketonate)]+PF6- complexes, with the CH3COCHCOCH3(acac) and CF3COCHCO(2-thienyl)(tta) derivatives characterised by X-ray structure determinations. The local Cu(II) environment ranges from distorted square-planar to an intermediate form of square-planar and tetrahedral. The beta-diketonate derivatives show varying stability towards methanolysis, giving [{Pt2(mu-S)2(PPh3)4Cu(OMe)}2]2+.
Alkylation reactions of [Pt 2 (μ-E) 2 (PPh 3) 4 ] with cis-1,4-dichlorobut-2-ene (cis-ClCH 2 CH=CHCH 2 Cl) gives the complexes [Pt 2 (µ-ECH 2 CH=CHCH 2 E)(PPh 3) 4 ] 2+ , which undergo a facile fragmentation reaction in ESI mass spectrometry, via a retro-Diels-Alder reaction and loss of 1,3-butadiene, giving the dichalcogenide species [Pt 2 (μ-E 2)(PPh 3) 4 ] 2+ .
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