Complexes of platinum(II) containing ferrocenylethynyl ligands: synthesis, characterization and spectroscopic and electrochemical properties.

A series of homoleptic and heteroleptic platinum(II) complexes [Pt(C[triple bond]CFc)2(L-L)] (L-L = COD 1, 1,1'-bis(diphenylphosphino)ferrocene (dppf) 2), Q2[cis/trans-Pt(C6F5)2(C[triple bond]CFc)2] (cis, Q = PMePh3, 3; trans, Q = NBu4, 4), (NBu4)[Pt(bzq)(C[triple bond]CFc)2] 5 (Hbzq = 7,8-benzoquinoline) and (NBu4)2[Pt(C[triple bond]CFc)4] 6 has been synthesized and characterized spectroscopically and the structures of 1.2CHCl3, 2 and 6.2H2O.2CH2Cl2 confirmed by single-crystal X-ray studies. The anion of complex 6, shows strong O-H...pi(C[triple bond]C) interactions and weaker C-Cl...pi(C[triple bond]C) contacts between the protons of two water and two CH2Cl2 molecules and the C(alpha)[triple bond]C(beta) of mutually cis alkynyl groups. In this complex the presence of additional O-H...H-C(Cp) and C-Cl...H-C(Cp) contacts gives rise to an extended bidimensional network. The optical and electrochemical properties of all derivatives have been examined. It is remarkable that for complexes 2 and 5 a facile oxidatively induced coupling, giving rise to 1,4-diferrocenylbutadiyne, is observed, this also having been proven by chemical oxidation.