Unexpected Formation of Ferrocenyl(vinyl)benzoquinoline Ligands by Oxidation of an Alkyne Benzoquinolate Platinum(II) Complex

Abstract

Oxidation of [Pt(bzq-κN,κC10)(C6F5)(η2-HC≡CFc)] (1) with PhICl2 and I2 affords the unusual halideferrocenyl(vinyl)benzoquinoline PtII derivatives [Pt{bzq-κN-η2-CH═C(X)Fc}(C6F5)X] (X = Cl (4a), I (4b)), arising from C–X and C–C coupling processes, together with small amounts of the corresponding PtIV products [{Pt(bzq-κN,κC10)(C6F5)X(μ-X)}2] (X = Cl (5a), I (5b)), respectively. Complexes 4 are very stable but they undergo easy displacement reactions with PPh3, yielding trans-[Pt(C6F5)X(PPh3)2] and the corresponding new functionalized (vinyl)benzoquinoline ligands [(Z)-bzq-CH═C(X)Fc] (X = Cl (6a), I (6b)). The dinuclear PtIV derivatives 5 are alternatively obtained in high yield by oxidation of the solvate [Pt(bzq-κN,κC10)(C6F5)(CH3COCH3)] (2). Treatment of 5 with dmso or direct oxidation of [Pt(bzq-κN,κC10)(C6F5)(tht)] (3) provides mononuclear [Pt(bzq-κN,κC10)(C6F5)X2(L)] (L = dmso (7a–c), tht (8a–c)) as a mixture of cis and trans isomers.