HETEROCYCLIC ORGANOTELLURIUM COMPOUNDS AS PRECURSORS FOR NEW ORGANOMETALLIC DERIVATIVES OF RHODIUM

The reaction of the pentamethylcyclopentadienylrhodium(III) dichloride dimer, [{Rh(eta-C5Me5)Cl-2}], with tellurophene in the presence of Ag (O3SCF3) afforded the expected [Rh(eta-C5Me5)(eta(5)-C4H4Te)][O3SCF3]( 2) 1 which on reaction with [Co(cp)(2)] (cp = eta-C5H5) gives a rhodac yclic material [Rh(eta-C5Me5){eta(5)-C5H4Rh(eta-C5Me5)}] 2. The reacti on of 2 with [Fe-3(CO)(12)] gave [Rh(eta-C5Me5){eta(5)-C4H4Fe(CO)(3)}] 3. The reaction of [{Rh(eta-C5Me5)Cl-2}(2)] with dibenzotellurophene, dbt, in the presence of Ag(O3SCF3) gives [Rh(eta-C5Me5)(dbt)][O3SCF3]( 2) 4, in which the mode of coordination of dbt in CDCl3 solution appea rs to be eta(1). The reaction of 4 with [Co(cp)(2)] and [Fe-3(CO)(12)] gave a variety of products including [Rh(eta-C5Me5)(C12H8)(eta(1)-dbt )] 5, a known dibenzoferrole, 6, and compound 7 in which the eta(1)-db t of 5 is substituted by CO. Also isolated were the known [{Fe(eta-C5M e5)(CO)(2)}(2)]8 and FeTe. The direct reaction of [{Rh(eta-C5Me5)Cl-2} (2)] and dbt gave [Rh(eta-C5Me5)Cl-2(eta(1)-dbt)]. Two complexes of 2- telluraindane were synthesized for comparison, [Rh(eta C5Me5)(C8H8Te)] [O3SCF3](2) 10 and [Rh(eta-C5Me5)Cl-2- (C8H8Te)] 11 the latter showing fluxionality about co-ordinated tellurium at room temperature. It is suggested that the magnitude of J((TeRh)-Te-125-Rh-103) has the potent ial to differentiate the modes of co-ordination of heterocyclic tellur ium compounds to rhodium. The crystal and molecular structures have be en determined for compounds 5, 7 and 9.