Reactions of [Re(NO)2(PR3)2][BArF4] complexes with phenylacetylene

Abstract

The reaction of [Re(NO)2(PR3)2][BArF 4] (R = cyclo-C6H13 (1a), Pri (1b); [BArF 4]– = [B(3,5-(CF3)2C6H3)4]) with phenylacetylene in the presence of a non-nucleophilic base, like 2,6-bis(tert-butyl)pyridine (BTBP) or ButOK, affords the phenylethynyl complexes [Re(C≡CPh)(NO)2(PR3)2] (R = cyclo-C6H13 (2a); Pri (2b)) in moderate yields. In the absence of a base, complexes 1a and 1b are transformed into the compounds [Re(C≡CPh)(CH=C(Ph)ONH)(NO)(PR3)2][BArF 4] (3a and 3b, respectively). The structure of complex 3a was confirmed by X-ray diffraction analysis. The latter reaction is proposed to be initiated by deprotonation of the terminal alkyne H atom by the bent nitrosyl ligand followed by the subsequent 1,3-dipolar addition of the ReN(H)O moiety to phenylacetylene.