Five-membered OsC 3N heterocycles from osmium azavinylidenes as precursors

Abstract

The azavinylidene osmium complex [(mes)Os(NCPh 2(P iPr 3)]PF 6 ( 3; mes = 1.3.5-C 6H 3Me 3), which was prepared in two steps from [(mes)OsCl 2(P iPr 3], CH 3CO 2Na/KPF 6 and HNCPh 2, has been shown to react with trifluoracetic acid to give the isomeric heterocycle [(mes) Os(NHC(Ph)C 6H 4)(P i Pr 3)]PF 6 ( 4) in almost quantitative yield. With CF 3CO 2D, the monodeuterated compound 4- d 4,containing a ND unit in the five-membered ring, is obtained. An analogue of 4 with the composition [(mes) Os(NHC(Ph)C 6H 4)(PMe 3)]X(X = PF 6 14a, SbF 6 14b) has been made both from [(mes)Os(NCPh 2)(PMe 3)]PF 6 12 and CF 3CO 2H and from [(mes)OsCl(NH CPh 2(PMe3)]SbF6 ( 13) and CF 3CO 2Ag. The reaction of 4 with NaH or KO tBu gives the uncharged heterocycle [(mes) Os(NC(Ph)C 6 H 4)(P iPr 3)] ( 15), while treatment of [(mes)OsCl 2(NHCPh2)] ( 19) with NaS tBu gives the related complex [(mes) Os(NH C(Ph)C 6H 4)(S t Bu)] ( 20). The crystal structure of 4 has been determined. kw]Osmium; Azavinylidene; Cyclometallation; Crystal structure; Arene complexes