Studies of the coupling of aryl isothiocyanates to bridging alkyne ligands in dirhenium carbonyl complexes

Reactions of the lightly stabilized dimetalated olefin complex Re(CO)[sub 4][trans-[mu]-HC=C(CO[sub 2]Me)]Re(CO)[sub 4](NCMe) (1) with aryl isothiocyanates have yielded a series of complexes having the general formula Re(CO)[sub 4][(E)-HC=C(CO[sub 2]Me)CN(Ar)=S]Re(CO)[sub 4] (2a, Ar = p-tolyl; 2b, Ar = Ph; 2c, Ar = p-chlorophenyl). Compounds 2a-c were formed by the loss of NCMe from 1 and the addition and insertion of one isothiocyanate molecule into one of the metal-carbon bonds to form a thioamido group that is chelated to one of the rhenium atoms. When heated to 98[degrees]C, complexes 2a-c were decarbonylated and converted into the dimeric complexes [Re-(CO)[sub 4](E)-HC=C(CO[sub 2]ME)CN(Ar)=S]Re(CO)[sub 3] B[sub 2] (3a, Ar = p-tolyl; 3b, Ar = Ph; 3c, Ar = Ph; 3c, Ar = p-chlorophenyl), in which the sulfur atoms of the thioamido groups bridge the two metal atoms. Decarbonylation of 2a-c at 80[degree]C in the presence of [Re(CO)[sub 4]([mu]-I)] B[sub 2] yielded the trirhenium complexes Re(CO)[sub 4][[mu]-(E)-HC=C(CO[sub 2]Me)CN(Ar)=S]Re[sub 2](CO)[sub 7] ([mu]-I) (4a, Ar = p-tolyl; 4b, Ar = Ph; 4c, Ar = p-chlorophenyl). 12 refs., 4 figs., 7 tabs.