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

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.