Regiospecific C(naphthyl)–H bond activation by platinum(II): Isolation, characterization, reactivity and TD-DFT study of the platinum(II) and platinum(IV) organometallates having [C,N,S] donor set

At room temperature, complex [Pt (η3-C4H7)Cl]2 or [K2PtCl4] regiospecifically activates the C2(naphthyl)–H bond of 2′-alkylthiophenylazo-1-naphthalenes (1, HL) and affords green cycloplatinates [PtIILCl] (2). The structure of platinum(II) cycloplatinate (2a) has been established by single-crystal X-ray crystallography. The platinum(II) centre is surrounded by a tridentate [C,N,S] ligand frame (L) and chloride ion in a distorted square planar fashion. The platinum(II) cycloplatinate (2a) contains a five-membered carboplatinacycle along with a five-membered (N,S) chelate ring. The cycloplatinates [PtIILCl] readily react with halogens X2 (X = Cl, Br, I) and afford blue violet platinum(IV) cycloplatinates [PtIV(C,N,S)X3] (3–5). Methyl iodide (CH3I) reacts with [PtIILCl] and produces [PtIILI] (6a & 6b). The structures of platinum(IV) cyclometallates (3a & 4b) have been determined by single crystal X-ray crystallography. Time dependent density functional study (TD-DFT) of representative cycloplatinates has been undertaken. The simulated optical spectra of the cycloplatinates are in good agreement with the experimentally observed spectra of the corresponding cycloplatinates.