Transition metal-fluorophosphine complexes

Many synthetic approaches have been employed and these are summarized below. Only in certain cases are the methods specific for a particular metal or ligand (Table VII). 

Trifluorophosphine complexes of nickel, palladium, and platinum have been obtained by direct reaction of PF3 with the metal at elevated temperatures and pressures (172). Similarly several fluorophosphine complexes of zero-valent nickel can be made under very mild conditions (60°C) using metallic nickel formed by decarboxylation of nickel oxalate 

HCo(PF3)4 is obtained in almost quantitative yield from the metal, PFg, and hydrogen (172), and when carbon monoxide is included in the 

It is noteworthy that there is no evidence for formation of pentakis-(trifluorophosphine)iron(O) when iron [made thermally by decomposition of iron(II)oxalate or iron pentacarbonyl] and 600 atm trifluorophosphine are heated at 300°C. (171) 

The strong reducing properties of certain fluorophosphines can, in certain cases, lead directly to fluorophosphine complexes of the metal in its zero-valent state (173, 234, 247), for example. 

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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). 

Since fluorophosphines form part of a general review of phosphorus fluorides (282), and there is an excellent account of transition metal-trifluorophosphine complexes (152), the present article is not intended to be comprehensive, but rather to highlight some of the more recent developments in this expanding area of inorganic chemistry. 

Electron Spin Resonance of Transition Metal Complexes B. A. Goodman and J. B. Raynor Recent Progress in the Chemistry of Fluorophosphines John F. Nixon... 

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). 

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. 

C. p7pMP Coupling Constants in Fluorophosphine-Transition Metal Complexes. ... 

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. 

In short, although it clearly remains uncertain what relative importance should be attached to the a and 77 contributions of the transition metal-phosphorus bond in metal-phosphine complexes, it is probably not without significance that fluorophosphines mainly stabilize the metal in an electronic configuration which maximizes the number of d electrons,... 

From Other Fluorophosphine-Transition Metal Complexes... 

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,... 

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