Interconversion of CN and CNH 2 ligands: electrosynthesis and X-ray crystallographic structures of trans-[W(CNH 2 )Cl(dppe) 2 ] and trans-[W(CNH 2 )Cl(dppe) 2 ][BF 4 ](dppe = Ph 2 PCH 2 CH 2 PPh 2 ): aminocarbyne (C–NH 2 ) or iminomethylenium (CNH 2 + ) ligands?

Electrochemical reduction of trans-[W(CN)Cl(dppe)2] in the prsence of phenol gives trans-[W(CNH2)Cl(dppe)2]3, which can be oxidised electrochemically or chemically to the paramagnetic cation trans-[W(CNH2)Cl(dppe)2]+4; X-ray crystallographic analyses of 3 and 4[BF4] suggest that the CNH2 group at both the 18 and 17e W-centres is best described as iminomethylenium (CNH2+); 3 and the deutero-complex trans-[W(CND2)Cl(dppe)2] reduce azobenzene with regeneration of the parent cyanide, the former giving hydrazobenzene and latter PhNDNDPh, suggesting that the CNH(D)2 complexes can behave as 2H(D) atom transfer reagents.