Synthesis, spectroscopic properties and crystal structure of mononuclear tricarbonylrhenium(I) chloride complexes carrying 6-functionalised quinoxalines

Two quinoxaline derivatives pqCH3 and pqCl (where pq stands for 2-(2′-pyridyl)quinoxaline) were prepared by condensation of 2-acetyl pyridyl with 2-amino-4-methylphenylamine or 2-amino-4-chlorophenylamine, correspondingly and were studied spectroscopically and electrochemically, in correlation with the originally reported pq. Their novel corresponded complexes namely, fac-[Re(CO)3Cl(L)] (where L = pqCH32 and pqCl 3) were synthesized, characterized, studied and compared to Re(CO)3Clpq, 1. Complex 2 crystallizes in space group C2/c with a = 20.4476(17) Å, b = 15.4521(13) Å, c = 15.2887(13) Å, β = 126.1210(11)°, Z = 8 and V = 3902.0(6) Å3. The substitution of –H by –CH3 or –Cl at 6-position of pq has a minor electronic effect on the pyridyl ring of the ligands, but seems to influence the quinoxaline moiety enough to alter the spectroscopical and electrochemical features.