Synthesis and reactions of amido-complexes of rhenium(I): isolation of new carbamate derivatives

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Abstract
On reaction of [Re(CO)2H(PPh3)3] with aroyl azides, RCON3(R = Ph or C6H4Me-p), amido-complexes of rhenium-(I), [Re(CO)2(NHCOR)(PPh3)2], may be isolated. I.r. data and the chemical behaviour of these new complexes suggest that the carbonyl group of the organic ligand is also involved in the co-ordination to the metal. Reactions of these complexes with neutral ligands (L) give [Re(CO)2L(NHCOR)(PPh3)2](L = CO or NBunH2), while second aryamines NR′2H (R′= Et or Prn) react only in the presence of carbon dioxide and lead to the formation of carbamate derivatives [Re(CO)2(O2CNR′2)(PPh3)2]. Analogous dithiocarbamate derivatives have been isolated by using CS2 instead of CO2. The amido-complexes also readily react with carboxylic acids, R″CO2H, to give carboxylato-derivatives [Re(CO)2(O2CR″)(PPh3)2](R″= H, Me, ClCH2, Et. or Ph), while with mineral acids HX (X = Cl or BF4) ionic amido-complexes [Re(CO)n(NH2COR)(PPh3)2]X (n= 2 or 3; R = C6H4Me-p) have been obtained. Theformate [Re(CO)2(O2CH)(PPh3)2] has also been obtained from the reaction of CO2with [Re(CO)2-H(PPh3)3].