Coordination behaviours of perimidine ligands incorporating fused N-donor heterocyclics towards rhenium(I) and -(V)

In this research study, the coordination behaviours of perimidine ligands incorporating fused N-donor heterocyclics towards rhenium in its oxidation states +I and +V are explored. The equimolar coordination reactions of 2-(benzothiazole)-2,3-dihydro-1H-perimidine (bzpm) and 2,3-dihydro-2-(pyridine)-1H-perimidine (H2pypm) with [Re(CO)5Br] afforded the rhenium(I) complexes: fac-[Re(CO)3(bzpm)Br](1) and fac-[Re(CO)3(pypm)Br](2), respectively. The imido rhenium(V) complex, cis-[Re(pyrnp)Br2(PPh3)](3) {H3pyrnp = 8-((1H-pyrrole)iminomethyl)naphthalene-1-amine} was isolated from the reaction of trans-[ReOBr3(PPh3)2] with a twofold molar excess of 2,3-dihydro-2-(1H-pyrrole)-1H-perimidine (pyrpm). These metal complexes were characterized via1H NMR-, IR-, UV–vis and Mass spectroscopy, melting point and conductivity measurements. Single crystal X-ray analysis provides a definitive confirmation of the structural elucidations of the metal complexes. The DNA binding interactions of the rhenium(I) complexes were evaluated through UV–vis titrations with Calf-Thymus (CT)-DNA.

Graphical AbstractThe equimolar coordination reactions of 2-(benzothiazole)-2,3-dihydro-1H-perimidine (bzpm) and 2,3-dihydro-2-(pyridine)-1H-perimidine (H2pypm) with [Re(CO)5Br] afforded the rhenium(I) complexes: fac-[Re(CO)3(bzpm)Br](1) and fac-[Re(CO)3(pypm)Br](2), respectively. The oxo-free rhenium(V) complex, cis-[Re(pyrnp)Br2(PPh3)](3) {H3pyrnp = 8-((1H-pyrrole)iminomethyl)naphthalene-1-amine} was isolated from the reaction of trans-[ReOBr3(PPh3)2] with a twofold molar excess of 2,3-dihydro-2-(1H-pyrrole)-1H-perimidine (pyrpm).Figure optionsDownload as PowerPoint slide