Phenyldichlorophosphine complexes

Platinum(II)15 and palladium(II)16 complexes of phosphorus trichloride undergo solvolysis in water and alcohols to form complexes with orthophosphorous acid or orthophosphite ligands (equation 6). Similar reactions occur between the palladium(II) phenyldichlorophosphine complex (8) and the diols ethyleneglycol and catechol, but new chelate rings are not formed (Scheme 2). Solvolysis also occurs with attack of diphenylphosphinic acid or a similar diphenylchlorophosphine complex (9) (equation 7). The palladium complexes (8) and (9) are unstable to excess methanol, water or base and undergo reduction. Similarly, the phosphorus trichloride gold(I) complex (10) is reduced by water, but forms stable products on reaction with alcohols (equation 8).15 During the above reactions, the phosphorus—metal bond remains intact and the overall process is one of substitution at phosphorus. 

At the time of our investigation the only known coordination compounds of chlorophosphines (aside from phosphorus trichloride complexes) were the nickel-(0) compounds, tetrakis(methyldichlorophosphine)nickel-(0) (20) and tetrakis-phenyldichlorophosphine) nickel- (0) (17). Tetrakis (methyldichlorophosphine) -nickel-(0) is noteworthy in that it represents a still rare example of the direct reaction of a ligand with an elemental transition metal to give a complex, while tetrakis (phenyldichlorophosphine) nickel- (0), like tetrakis (trichlorophosphine) -nickel-(0), was obtained readily via the carbonyl. AD chlorophosphine-nickel-(O) complexes, including the phosphorus trichloride complex, Ni(PCl3)4, are compounds relatively stable in the atmosphere, but show poor stability in almost any organic solvent, even under strictly anaerobic conditions. 

In spite of its highly strained Dewar structure 1 is stable and may be kept in a refrigerator for several years. It isomerizes to the aromatic isomer at high temperature (half-life in benzene at 160 C was 5.1 h). The treatment of the Dewar thiophene with triphenylphosphine did not cause the elimination of sulfur, but instead accelerated the isomerization to the aromatic isomer. This catalytic acceleration is limited to tervalent phosphorus compounds but phosphorous trichloride or phenyldichlorophosphine are ineffective. An adduct of diphenylchlorophosphine with the Dewar thiophene was postulated to be a ff-complex with a P—S bond. It decomposed spontaneously to the thiophene and the phosphine as shown in Eq. (9).15 Recently,... 

A reaction analogous to a Friedel-Crafls alkylation is the reaction of PCI3 with benzene to produce phenyldichlorophosphine. At least a full mole of aluminum chloride is required because it combines with the product to form a complex (1). 

Phenyldichlorophosphine (2) is prepared by gradually heating a mixture of benzene, phosphorus trichloride, and aluminum chloride until a yellow solution of the complex (1) results (2 hrs.) and then refluxing for 1 hr. The heat source is... 

---