The tertiary phosphines (L) PPh2(2-methoxyphenyl), PButMe(2-methoxyphenyl), PBut2(2-methoxyphenyl), and PPh2(2-ethoxyphenyl) were prepared. Complexes of these ligands and of PMe2(2-methoxyphenyl) with platinum-(II) halides are described. These complexes on heating are converted to O-metallated chelates, e.g. trans-[PtCl2{Ph2P(2-methoxyphenyl)}2] gives cis-[Pt(Ph2PC6H4O)2]. PMe2(2-methoxyphenyl) is much more difficult to metallate but the complex [Ptl(Me2PC6H4O)(Me2PC6H4OMe)] was prepared. C-Metallated derivatives containing six-membered chelate rings were prepared by heating the ligand or [PtCl2L2] with [PtCl2(RCN)2] in xylene. Metathesis and bridge splitting reactions are described. 1H and 31P N.m.r. and i.r. data are given and discussed.