Zerovalent platinum olefin and acetylene complexes Pt(OL)L, have been isolated for OL = C, CI , , C,F4, CF,CECCF,, (CF,),CO, and CS, (but not for non-activated olefins) for a variety of phosphine and arsine ligands Lfrom a reaction with the air-stable derivative bis(l.5-diphenylpenta-I ,4-dien-3-one), Pt(dpo),. An intermediate complex, Pt(dpo) L, , involving metal co-ordination to one double bond of the diene ligand, undergoes olefin displacement by OL to give the same derivatives. l H and 13C N.m.r. spectra for the products Pt(dpo)L, and 19F n.m.r. specrra for the species Pt(OL) (PEt,), where OL = C, F, and CF,C' =CCF, are reported. 0 air-stable complex * bis( 1,5-diphenylpenta-1,4-die11-3one) platinum ( 0 ) , Pt (dpo),.

13C N.m.r. chemical shifts, 8, and 1J(1Q6Pt-13C) coupling constants have been obtained for a series of anionic, neutral, and cationic platinum( 11) carbonyl complexes incorporating 13C0. In the series [PtX(CO) L.L'] with the group X trans to the labelled carbonyl group, for constant X a decrease in 6 has been observed for the 13C0 with increasing negative charge on the complex. Little variation in 6 has been observed with change in the cis-ligand.Two ranges of values for lJ(lssPt-13C) have been obtained for variation of trans-group X : for ligands with high rrans-influence the coupling is in the range 960-990 Hz, whilst for ligands with low trans-influence the coupling falls in the region 1 658-1 817 Hz.

The synthesis of [PtzCI,(R3M),][BF4]z, and its cleavage with carbon monoxide to form the cationic carbonyl species [PtC1(CO)(R3M),]+ is described for R = ethyl or phenyl, and M = As or Sb. A comparison of the physical properties and spectroscopic data of these compounds, and the analogues for M = P is made with related complexes of other transition metals. Unlike their phosphine analogues, these species and the stibine-stabilized cationic carbonyls do not produce the corresponding hydrides on reaction with water in the presence of a salt catalyst. These differences in chemical reactivity are related to the basicity of the ligands.

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Die cis‐Komplexe (II) werden durch Spaltung der kationischen dimeren Komplexe (I) mit entsprechenden Na‐Salzen erhalten und bilden bei Behandlung mit B‐trifluorid die dimeren Komplexe (III) mit dem Anion‐Liganden als Brücke.