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.

Graphical abstractRegiospecific C2(naphthyl)–H bond activation in 2′-alkylthiophenylazo-1-naphthalenes has been achieved with platinum. Isolation, characterization, structure and reactivity of the divalent cycloplatinates are described.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Regiospecific C(naphthyl)–H bond activation of 2′-alkylthiophenylazo-1-naphthalenes has been achieved with Pt(II). ► Representative divalent cycloplatinate been structurally characterized. ► Oxidative addition reactions of dihalogens to square-planar Pt(II) complexes have been reported. ► TD-DFT study on cycloplatinates is done.