Biphenyl monodentate ligands

For example, the differences between CP and Br in complexes of the type [Ru (r 6-arene)(en)Z]+, where arene is biphenyl, indane or benzene, is not dramatic, however, when Z = I the hydrolysis is slower (3- to 7-fold). Other leaving groups such as pyridine or pyridine derivatives can slow down the hydrolysis further and even block it almost completely on biologically-relevant time scales. Such complexes are not cytotoxic towards cancer cells within 24-h drug exposures. There are a few exceptions such as [Ru(ri6-hexamethylbenzene)(en)(SPh)]PF6, where the monodentate ligand is thiophenolate. This complex does not hydrolyse, but intrigu-ingly is active. The mechanism of activation of this complex is different (vide infra). 

Pt(en)(N03)2] and [Pt(OTf)2L2] (L = mono- or 1/2 bidentate tertiary phosphine) or dinuclear complexes of the type [Pt2(OTf)2(/i-monodentate tertiary phosphine cr-aryl = 4, -biphenyl, / -terphenyL 4,4 -benzophenone, etc.) other structural motifs employing platinum(II) have also been reported.2 0 The addition of bridging, multidentate N-donor ligands of various shapes and sizes to the labile complexes in a suitable solvent system has afforded several classes of discrete, plat-inum(II)-containing polygons, polyhedra, and catenanes. 

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