RhCl PPh

RhCls PPh C°> RhCl3 (CO) (PPh3)2 RhCl(CO)(PPh3)2 RhCl3(CO)(PPh3)2... 

In summary, the flash photolysis of RhCl(CO) (PPh in benzene leads principally to formation of the coordinatively unsaturated Wilkinson s catalyst intermediate RhCl (PPh-j) 2 (or its solvated analog). The reactions of this species are summarized in Scheme I. 

The reaction of RhCl(PPh)3 with pentane-2,4-dione (equation 183) is more complex, some rra s-[RhCl(CO)(PPh3)2] is formed as a result of carbonyl abstraction in a side reaction.920 An even more complex reaction results from the trapping by RhX(PPh3)3 (X = Cl, Br) of the SO moiety produced in the decomposition of stilbene episulfoxide (65 equations 184). The dimeric product is unstable in the presence of PPh3 and is reduced to the starting material (equation 185).921... 

Upidus has reported that Rh4(CO), . iRhCCOiClj and RhCl(PPh )3 catalyze CO reduction (0 CO in the presence of AlBr and molecular hydrogen. Traces of Cj Cj alkanes were formed along with CO. Chlorotrisftriphcnyl-phosphine)rhodium did not convert 10 the corresponding carbonyl compound 12911. 

Table I. Activation of RhCl(PPh J3 Catalyzed Alkene Hydrogenations Inhibited by Triphenylphosphine Using PS-S03Ag.a J J...

Since the discovery of Wilkinson s complex RhCKPPh ) in 1966 [39], many useful catalytic reactions have been reported which are catalyzed by this and related complexes. In particular, RhCl(PPh is a very useful catalyst precursor for hydrogenation of variety of alkenes. The chemical reaciivitv of RhCl(PPh3)3 is summarized in Scheme 11.4 [40]. 

RhCl(PPh,)3] -1- EtjSiH + EtjN [RhH(PPh3)4] + Et,SiCl—NEt3... 

The reaction of [RJi2Cl2(CgHi4)4] with 2-aminopyridine led to a species believed to be a cationic solvated rhodium(I)-aminopyridine complex. This was more active than [RhCl(PPh,)3] or [RuH(Cl)(PPh3)3] for the hydrogenation of cyclohexene. The mechanism was thought to involve oxidative addition of hydrogen to rhodium(I) prior to alkene coordination. 

Cyclohexene is converted to cyclohexene oxide with 7 - 62 % selectivity in the presence of catalysts consisting of a mixture of two metal complexes, e.g. RhCl(PPh ) + Mo0(02)2HMPT(H20) [109]. The Rh... 

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