Synthesis and characterization of a pentadentate Schiff base N3O2 ligand and its neutral technetium(V) complex. X-ray structure of {N,N'-3-azapentane-1,5-diylbis(3-(1-iminoethyl)-6-methyl-2H-pyran-2,4(3H)-dionato)(3-)-O,O',N,N',N''}oxotechnetium(V)