Preparation of aryldiazene complexes of rhodium

Aryldiazene complexes [Rh(ArN=NH)(CO) (PPh3)(3)]BF4 (1) and [Rh(ArN=NH)(PPh 3)(4)]BF4 (2) (Ar = C6H5 or 4-CH3C6H4) were prepared by allowing hydride sp ecies RhH(CO)(PPh3)(3) and RhH(PPh3)(4) to react with aryldiazonium cations at low temperature. The complexes were characterised by IR and H-1-, P-31- and N-15-NMR spectra, using N-15 labelled compounds. Free aryldiazene ArN= NH species and [Rh{PPh(OEt)(2)}(4)]BF, were obtained by reacting the hydrid e RhH[PPh(OEt)(2)](4) with aryldiazonium cations in CH2Cl2 at - 80 degreesC . Reactions of aryldiazene complexes 1 and 2 with H-2 (1 atm) were also stu died, but did not lead to arylhydrazine derivatives. (C) 2001 Elsevier Scie nce B.V. All rights reserved.