STUDIES ON INTERACTION OF TRANSITION-METAL COMPLEXES WITH ISOCYANIDES .40. REACTIONS OF DICOBALT OCTA(ISOCYANIDE) WITH 2-BROMOACETOPHENONE

The reaction of Co-2(XylNC)(8) (Xyl = 2,6-Me(2)C(6)H(3)) with 2-bromoacetophenone gave 2,3-bis(2,6-xylyl)imino-5-phenyl-2,3-dihy- drofuran (1a) and the cobalta-azacyclopentane derivative CoBr(PhCOCH)(XylNC)(6) (2a). Structures of 1a and 2a were determined by X-ray analyses; la is a furan derivative and 2a has a distorted octahedral structure containing a five-membered metallacyclic moiety formed by an multiple insertion of isocyanide into a Co-C bond. Similar treatment at reflux in the presence of xylyl isocyanide gave two kinds of octahedral compounds, 3a and 4a, having similar formula composition CoBr(PhCOCH)(XYINC)(5); 3a was found by X-ray analysis to have a cobaltacycle structure, containing a tridentate ligand consisting of sigma carbon, carbene and O-coordination sites, and 4a was proposed to have a cobalta-azacyclobutane framework.