Synthesis, characterization and DFT studies of complexes bearing [Re(CO)3]+ core and reactivity towards cyanide ion

Abstract

Mononuclear rhenium(I) complexes having fac-[Re(CO)3]+ core of general formula fac-[Re(CO)3(L)Cl] have been synthesized in excellent yield by reacting [Re(CO)5Cl] with L1 and L2in a ratio of 1:1 in toluene under inert atmosphere. Here L1 and L2 are N-((quinolin-2-yl)methylene)-9H-fluoren-2-amine and N-((anthracen-10-yl)methylene)quinolin-8-amine respectively. Spectroscopic measurements such as NMR, ESI-MS and IR spectroscopy were used to ensure the formations of desired complexes. Molecular structures of fac-[Re(CO)3(L1)Cl] and fac-[Re(CO)3(L2)Cl] were confirmed by single-crystal X-ray diffraction. The ligands are emissive whereas the metal complexes are weak emitter. A remarkable change in absorption as well as emission behavior was observed in complex 2 upon addition of cyanide ion. Interruption in intraligand charge transfer in complex 2 is the probable reason for the obvious change in spectral response of the same. 1H NMR titration was performed as the evidence of the previously stated fact. The ground and excited-state geometries, absorption properties of rhenium(I) complexes were examined by DFT and TDDFT methods. The natural transition orbital (NTO) and analysis reveal the nature of excitations.