New aliphatic and aromatic thiolato-bridged complexes of palladium(II) and platinum(II)

Pressure-Assisted Hetero- and Homodialkylation of Sulfide in [Pt2(μ-S)2(dppp)2]: One-Pot Conversion of {Pt2(μ-S)2} into {Pt2(SR)2} and {Pt2(SR)(SR′)}

Heterodialkylation of [Pt2(mu-S)2(dppp)2] (dppp = Ph2P(CH2)3PPh2) was achieved under high pressure (10 kbar). This enabled the synthesis of rare diplatinum complexes with structurally diverse thiolate bridges, such as [Pt2(mu-SC5H10CO2CH2CH3)(mu-SC3H7)-(dppp)2](PF6)2, which was crystallographically identified. Complete homodialkylation was also achieved under similar conditions (6 kbar at room temperature), thus permitting the isolation of [Pt2(mu-SC2H4CO2CH2CH3)2(dppp)2]-(PF6)2. The isolation of these complexes extends the applications of high-pressure chemistry to thiolato homo- and heterobridged complexes that are otherwise not accessible.

Stable diplatinum complexes with functional thiolato bridges from dialkylation of [Pt2(µ-S)2(P–P)2] [P–P = 2 × PPh3, Ph2P(CH2)3PPh2]

The normally robust monoalkylated complexes [Pt(2)(mu-S)(mu-SR)(PPh(3))(4)](+) can be activated towards further alkylation. Dialkylated complexes [Pt(2)(mu-SR)(2)(P-P)(2)](2+) (P-P=2 x PPh(3), Ph(2)P(CH(2))(3)PPh(2)) can be stabilized and isolated by the use of electron-rich and aromatic halogenated substituents R [e.g. 3-(2-bromoethyl)indole and 2-bromo-4'-phenylacetophenone] and 1,3-bis(diphenylphosphino)propane [Ph(2)P(CH(2))(3)PPh(2) or dppp] which enhances the nucleophilicity of the {Pt(2)(mu-S)(2)} core. This strategy led to the activation of [Pt(2)(mu-S)(mu-SR)(PPh(3))(4)](+) towards R-X as well as isolation and crystallographic elucidation of [Pt(2)(mu-SC(10)H(10)N)(2)(PPh(3))(4)](PF(6))(2) (2a), [Pt(2)(mu-SCH(2)C(O)C(6)H(4)C(6)H(5))(2)(PPh(3))(4)](PF(6))(2) (2b), and a range of functionalized-thiolato bridged complexes such as [Pt(2)(mu-SR)(2)(dppp)(2)](PF(6))(2) [R= -CH(2)C(6)H(5) (8a), -CH(2)CHCH(2) (8b) and -CH(2)CN (8c)]. The stepwise alkylation process is conveniently monitored by Electrospray Ionisation Mass Spectrometry, allowing for a direct qualitative comparison of the nucleophilicity of [Pt(2)(mu-S)(2)(P-P)(2)], thereby guiding the bench-top synthesis of some products observed spectroscopically.

Pt(ii) mono-carbonyl complexes of a cyclometallating 2-(2′-thienyl)-(pyridinato-C,3N′) ligand: nature and dynamics of the lowest excited state of the chloro- and thiolato-complexes

The synthesis of a cyclometallated Pt(II) thiolate carbonyl complex Pt(thpy)(CO)(mts), (thpy = 2-(2'-thienyl)-pyridinate, mts = methylthiosalicylate) is reported. A combination of emission and time-resolved infrared (TRIR) techniques revealed for both Pt(thpy)(CO)(mts) and its chloride analogue Pt(thpy)(CO)Cl the predominant intra 2-(2'-thienyl)-pyridinate 3pi pi* character of the lowest electronic excited state. The unusually short lifetime (780 ps) of the intraligand 3pi pi* lowest excited state of Pt(thpy)(CO)(mts) indicates that this electronic state is influenced by another close-lying excited state, probably charge-transfer in origin.