Tricarbonyl Complexes of Rhenium(I) with Acetylpyridine Benzoylhydrazone and Related Ligands

Novel rhenium(I) tricarbonyl complexes have been prepared by reactions of (Et 4 N) 2 [Re(CO) 3 Br 3 ] with acetylpyridine benzoylhydrazone, Hapbhyd, di(2‐pyridyl)ketone benzoylhydrazone, Hpy 2 bhyd, bis(2‐pyridine)ketone, py 2 CO, and pyridinealdehyde terephtalaldehydebishydrazone, pytehyd. The ligands remain protonated when no supporting base is added and the following complexes have been isolated: [Re(CO) 3 Br(Hapbhyd)], [Re(CO) 3 Br(Hpy 2 bhyd‐py, hyd)], [Re(CO) 3 Br(Hpy 2 bhyd‐py 1 , py 2 )], [Re(CO) 3 Br(py 2 CO‐N, N)] and [Re(CO) 3 Br(pytehyd)]. Addition of triethyl amine results in deprotonation of Hapbhyd and the formation of [Re(CO) 3 (OH 2 )(apbhyd)], whereas Hpy 2 bhyd is hydrolysed and a rhenium complex with the monoanionic bis(2‐pyridyl)hydroxymethanolato ligand, {py 2 C(OH)O} ‐ , is formed. The same compound, [Re(CO) 3 {py 2 C(OH)O}], is obtained when triethyl amine and water are added to a mixture of (Et 4 N) 2 [Re(CO) 3 Br 3 ] and py 2 CO. The air‐stable products have been studied by spectroscopic methods and X‐ray crystallography.