Preparation of diethylcyanamide and cyanoguanidine complexes of manganese and rhenium

Diethycyanamide complexes [M(NCNEt2)(CO)nL5−n]BPh4 (1a–5a) [M = Mn, Re; n = 1, 2, 3; L = PPh(OEt)2, P(OEt)3] were prepared by allowing hydrides MH(CO)nL5−n to react first with triflic acid (HOTf) and then with an excess of diethylcyanamide. The related cyanoguanidine derivatives [M{NCN(H)C(NH2)NH}(CO)nL5−n]BPh4 (1b–4b) were prepared by reacting hydrides MH(CO)nL5−n first with an equivalent of HOTf and then with an excess of cyanamide NCNH2 or, alternatively, with cyanoguanidine. Bis(diethylcyanamide) complexes MBr(NCNEt2)2(CO)3 (6, 7) were prepared by allowing pentacarbonyl species MBr(CO)5 to react with an excess of cyanamide NCNEt2. The complexes were characterised by spectroscopy (IR, 1H, 31P, 13C NMR) and by X-ray crystal structure determination of [Mn(NCNEt2)(CO)2{PPh(OEt)2}3]BPh4 (2a) and ReBr(NCNEt2)2(CO)3 (7a).