Fluorophosphines with transition metals

Knowing all these facts, especially the difficult access to fluorophosphines and the poor donating abilities of phosphorus trifluoride (5, 6), we decided to use another approach, which readily led to a number of coordination compounds with fluorophosphine ligands—namely, the fluorination of chlorophosphines already coordinated to the transition metal, where the 3s electrons of phosphorus are blocked by the complex formation. There was no reaction between elemental nickel and phosphorus trifluoride, even under extreme conditions, whereas the exchange of carbon monoxide in nickel carbonyl upon interaction with phosphorus trifluoride proceeded very slowly and even after 100 hours interaction did not lead to a well defined product (5,6). 

By far the most extensively used synthetic route involves the technique of reductive fluorophosphination developed by T. Kruck and co-workers (174), who have made many important contributions to the development of the field of transition metal-PF3 chemistry. In this method the appropriate metal halide is heated in an autoclave (usually copper-lined) with reducing agents, e.g., copper or zinc, in the presence of PF3(50-500 atm) (method C). For example,... 

A variety of synthetic routes to monoene and polyene tri-fluorophosphine-transition metal complexes have been devised. Direct photochemically induced reaction of a metal-PF3 complex with an activated alkene or diene (method A) has proved useful only for iron, the products being either [Fe(PF3)4(alkene)J or [Fe(PF3)3(diene)] (194). Mixed carbonyl-trifluorophosphine complexes of the type [Fe(PF3)x(CO)3 x(diene)] result from either thermal or photochemical reactions of dieneiron carbonyl complexes and PF3 (52, 53) (method B). The compounds are fluxional. 

Fluorophosphines are tervalent phosphorus compounds containing phosphorus-fluorine bonds and they often show markedly different chemical behavior compared with other halogenophosphines. This article is mainly concerned with recent advances in the chemistry of derivatives of PF 3 of the type PF3 X , with particular reference to (a) synthesis of new structural types, (6) the role of fluorophosphines as ligands, particularly in transition metal complexes, and (c) nuclear magnetic resonance (NMR) studies. 

Oxidation of trifluorophosphine by halogens is well known (282) and although corresponding reactions with alkyl or aryl fluorophosphines have received only little attention, it has become apparent that oxidation to the pentavalent phosphorus fluorides can be brought about by a wide variety of reagents. In certain cases the reducing property of the fluoro-phosphine has been utilized in the synthesis of zero-valent transition metal fluorophosphine complexes (Section IX). 

Alternatively by treating trifluorophosphine complexes with barium hydroxide in tetrahydrofuran, one fluorine atom can be replaced, and barium salts containing anionic fluorophosphine-transition metal com-... 

A striking feature of fluorophosphine-transition metal complexes is their high thermal stability, and this often contrasts markedly with the corresponding carbonyl derivative, e.g., HCo(CO)4 decomposes to an appreciable extent below room temperature, whereas HCo(PF3)4 is stable up to 250°C. The only exceptions appear to be some 4d metal complexes,... 

Observations have been made which support coordination of the dialkyl-amino fluorophosphine ligands to the transition metal through phosphorus, rather than through nitrogen, whereas in the reaction of (CH )2NPp2 with some boron acceptor molecules coordination both through phosphorus or nitrogen was observed (1). 

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