Carbene complexes of cycloplatinated 1H-indole-1-methyl-2-(2′-pyridine). The crystal and molecular structure of σ-{Pt[1H-indole-1-methyl-2-(2′-pyridinyl-C3,N′](DMSO)Cl} and of σ-{Pt[1H-indole-1-methyl-2-(2′-pyridinyl-C3,N′)][C(OCH2CH3)(CH2C6H5)]Cl}

Reaction of 1-methyl-2-(2′-pyridinyl)-1H-indole (1) with PtCl2(DMSO)2 (DMSO=dimethylsulfoxide) gave the cycloplatinated product 2; X-ray structure determination of 2 showed a metallation to platinum via the C3 carbon of the indole nucleus, which is chelated to the metal via the pyridine nitrogen atom. Compound 2 reacts with neutral ligands such as CO, ButNC, styrene and phenylacetylene, to give compounds 3–6 respectively, where DMSO is replaced by the neutral ligands. The phenylacetylene derivative 6 reacts with ethanol to give the carbene complex 7, whose X-ray structure has been determined. Related carbene complexes with other alcohols and other acetylenic derivatives have also been synthesised.