Rhodium, aryl isocyanides

The preparations of a number of rhodium(I) complexes of isocyanides, some of them new, have been described. The newtetrakis(methyl isocyanide) complex, [Rh(CNCH3)4], was isolated as salts of various anions from reactions of RhClj -3H20 or [(l,S-CgH,2)RhCl]2 and this isocyanide ligand (11), and several [Rh(CNR)4]+ alkyl and aryl isocyanide complexes (R= Bu, Pr, /)-C6H4C1, /.-CSH4CH3, and P-C6H4OCH3) have... 

Rhodium(I) or polymer supported rhodium(I) compounds catalyzed the formation ofFefCO - CNR L (x = 1 - 3 R = Bu, xylyl L = MA, citra-conic anhydride, acrylamide) (29, 30), and the dimer [CpFe(CO)2]2 catalyzed the stepwise substitution of carbonyl groups in CpFeI(CO)2 to give CpFeKCO - CNR) (x = 1,2 R = Bu, xylyl) in 60-80% yields. A nonchain free-radical mechanism was proposed for the latter reaction (28). The compounds CpFeX(CO)2 x(CNR)x (x = 1,2 X = halide, SiMe3) are known for a range of alkyl and aryl isocyanides (169-171). 

Table 2 Polymerization of aryl isocyanides 28a-c catalyzed by rhodium complexes 27...

In 1975 it was found that cationic aryl isocyanide complexes of rhodium(I) formed aggregates in solution via the formation of weak metal-metal interac-... 

An analogous mode of reaction is observed in the C-CN cleavage of ben-zonitriles with sUylmetal complexes [72]. For example, a silylrhodium complex initially forms an r -iminoacylrhodium complex (Scheme 1.55). The aryl group of the iminoacyl moiety migrates onto rhodium to form a rhodium isocyanide complex. 

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