Fluorophosphines

Fluorination of hexamethylphosphoramide with ammonium fluoride gives 85-90% yield of the insecticide bis(dimethylamine)fluorophosphine oxide (Dimefox) [5(1] (equation 18). 

Recent Progress in the Chemistry of Fluorophosphines John F. Nixon... 

A. Preparation.—Halogen displacement reactions have been used to prepare a number of new aminofluorophosphines. Aminodifluorophos-phine (1) has been prepared for the first time, from either bromodifluoro-phosphine or chlorodifluorophosphine, and ammonia. Studies of its n.m.r. spectrum have been made (see Chapter 11). The related NN-difluoroaminodifluorophosphine (2) has been prepared, from difluoroiodo-phosphine, and found to be explosive. Two syntheses of A-alkyl-amino-difluorophosphines have been reported, one of which was complicated by the subsequent formation of the phosphorane (3) and the bis-(A-alkylamino)fluorophosphine (4). 

Bis( 73-allyl)nickel(0) and bis( 75-pentadienyl)iron(II) have been used as starting materials in the preparation of [Ni(PF3)4] and [Ni(PF2H)4], 0 The electronic structure of the fluorophosphine com-... 

Caution. Since many of the fluoro derivatives of the oxygen acids of phosphorus are known10 to he extremely TOXIC and since detailed and reliable toxicity data on all the compounds considered here are not available, all these fluorophosphine derivatives should be handled as though they were highly toxic materials. 

Lines, E.L. and Centofanti, L.R, Preparation and characterization of vinyldi-fluorophosphine, Inorg. Chem., 13, 1517, 1974. 

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

Diethyl phosphinate Diethyl fluorophosphinate (see Note 2 below)... 

Further details of the preparation of (phosphazenyl)fluorophosphines (10) have appeared.16 The products were characterized by i.r., mass, and n.m.r. spectroscopy... 

CjHj(,). These compounds react with anhydrous HX (X = Cl or Br) to yield the halogenated-fluorophosphine complexes e.g ... 

Fluorophosphates, 16 183 Fluorophosphine complexes with borane, 13 439-444 coordination, 13 41CM14 bonding, in, 13 410-414 with nontransition metal halides, 13 445-447... 

Organic derivatives of phosphorus trichloride—i.e., chlorophosphines of the types RPC12 or R2PC1—had never been fluorinated. We assumed the hitherto unknown fluorophosphines to be possibly interesting ligands in coordination chemistry. Such expectations were supported by earlier observations of Chatt (5, 6) and Wilkinson (32), who found that the parent compound phosphorus trifluoride as a ligand in certain coordination compounds with platinum or nickel behaved very much like carbon monoxide. 

It must be concluded, therefore, that fluorophosphines are strongly reducing, a fact which was confirmed in further attempts at their preparation, using different reagents in the fluorination of chlorophosphines. There was either no reaction at all under the experimental conditions—e.g., with alkali fluorides in benzene as a solvent—or the trivalent phosphorus in the starting chlorophosphine was readily converted to the quinquevalent state—e.g., when phenyldichlorophosphine reacted with sodium fluoride in the presence of an antimony trioxide catalyst in a polar solvent such as acetonitrile to give phenylphosphonic difluoride. Recent Russian work showed that phenyldichlorophosphine was converted into phenyltetrafluoro-phosphorane, C6H5PF4, when it reacted with antimony trifluoride (34),... 

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). 

In our study of the fluorination of coordinated chlorophosphine ligands (23), we started out with tetrakis(trichlorophosphine)nickel-(0), which could previously be converted into tetrakis(trifluorophosphine)nickel-(0) by displacement of the coordinated phosphorus trichloride with excess phosphorus trifluoride in a sealed tube (32). The limitations of this method, requiring the use of phosphorus trifluoride, a low boiling gas, under pressure, and involving the mechanical separation of the fluorophosphine complex from phosphorus trichloride, are obvious, and the yield was low. A straightforward method for the synthesis of this interesting compound was found in the fluorination of the coordinated phosphorus trichloride with potassium fluorosulfinate ... 

Using the potassium fluorosulfinate method further fluorophosphine-nickel-(O) complexes could be prepared (23), according to ... 

The comparatively simple method of preparation of tetrakis (trifluorophos-phine)nickel-(0) encouraged some scouting experiments on its still unexplored chemistry. Whereas the compound is hydrolytically remarkably stable, it was found to react readily with amines and ammonia with complete aminolysis of the phosphorus-fluorine bonds. Very typical of tetrakis(trifluorophosphine) nickel-(0) and similar fluorophosphine and chlorophosphine complexes of zerovalent nickel is the rapid decomposition with precipitation of elemental nickel by aqueous alkali hydroxide. 

In the course of a study of the formation of fluorophosphoranes from chloro-phosphines (22) we observed one exception in the compound chloromethyldi-chlorophosphine, which reacted smoothly with antimony trifluoride to give the flammable fluorophosphine, C1CH2PF2, under conditions where many other chloro-phosphines were invariably converted into fluorophosphoranes. As this fluorophosphine is readily available, its interaction with a metal carbonyl derivative was studied, and cycloheptatriene molybdenum tricarbonyl, obtained from the reaction of molybdenum hexacarbonyl with cycloheptatriene (I, 2), was chosen as a starting compound. 

The tris(chloromethyldifluorophosphine)molybdenum tricarbonyl exhibited strong CO absorptions typical for terminal CO groups at 2038 and 1970 cm.-1. Strong P-F absorptions were found at 866 and 842 cm.-1, which in view of the above-mentioned observation in the case of tetrakis(trifluorophosphine)nickel-(0) may also be representative ef the uncoordinated fluorophosphine. Compared with molybdenum tricarbonyl derivatives with nitrogen compounds as donor mole-... 

The chemical and thermal stability of the fluorophosphine complexes is markedly increased in every case over the chlorophosphine complexes, none of the latter being volatile. The stability of the fluorophophine complexes as compared with the parent carbonyl is also noteworthy. While nickel carbonyl is distillable only with considerable decomposition, tetrakis(trifluorophosphine)nickel-(0) is far more stable on distillation at atmospheric pressure, and can also conveniently be handled in a high-vacuum system. 

Chloromethyldifluorophosphine ignites immediately in the atmosphere and consequently should be handled under nitrogen or in a vacuum line throughout. A sample of the fluorophosphine stored at approximately 0° for several weeks contained a sizable amount of chloromethyltetrafluorophosphorane, C1CH2PF4 (22), together with a solid material, as indicated by the F19 NMR spectrum of the former. 

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