An unusual reaction of Rh(SbPh3)(3)(CO)Cl with propargyl halides: the formation of rhodiacyclopent-3-ene-2-one complexes

Reactions of Rh(SbPh3)(3)(CO)Cl (1) with PhC=CCH2X (X=Cl, Br, p-TolSO(3)) a nd with HC=CCH2X (X=p-TolSO(3), PhSO3) in CH2Cl2 at room temperature result in the formation of the propargyl complexes Rh(SbPh3)(2)(eta(1)-CH2C=CPh)( CO)(Cl)X and the allenyl complexes Rh(SbPh3)(2)(eta(1)-CH=C=CH2)(CO)(Cl)X, respectively. However, treatment of 1 with unsubstituted propargyl halides under similar conditions unexpectedly affords the rhodiacyclopent-3-ene-2-o ne complexes Rh(SbPh3)(3)(eta(2)-C(=O)CH=CXCH2)Cl (X=Cl (5), Br (6)). The m olecular structure of 5 was elucidated by an X-ray diffraction analysis of 5.1/2CH(2)Cl(2). (C) 1998 Elsevier Science S.A. All rights reserved.