Preparation of diethylcyanamide and cyanoguanidine complexes of manganese and rhenium

Diethycyanamide complexes [M(Ntriple bond; length of mdashCNEt2)(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{Ntriple bond; length of mdashCN(H)C(NH2)double bond; length as m-dashNH}(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 Ntriple bond; length of mdashCNH2 or, alternatively, with cyanoguanidine. Bis(diethylcyanamide) complexes MBr(Ntriple bond; length of mdashCNEt2)2(CO)3 (6, 7) were prepared by allowing pentacarbonyl species MBr(CO)5 to react with an excess of cyanamide Ntriple bond; length of mdashCNEt2. The complexes were characterised by spectroscopy (IR, 1H, 31P, 13C NMR) and by X-ray crystal structure determination of [Mn(Ntriple bond; length of mdashCNEt2)(CO)2{PPh(OEt)2}3]BPh4 (2a) and ReBr(Ntriple bond; length of mdashCNEt2)2(CO)3 (7a).