Physico-chemical properties of the first metal compound of di-2-pyridylketone p-nitrophenoxyacetic acid hydrazone (dpknxh), fac-Re(CO)3(κ2-Npy,Npy-dpknxh)Cl
Di-2-pyridyl ketone p-nitrophenoxyacetic acid hydrazone (1), obtained from acid-catalyzed condensation of di-2-pyridyl ketone (dpk) with p-nitrophenoxyacetic acid hydrazide, reacts with Re(CO)5Cl in refluxing toluene to form fac-Re(CO)3(κ2-Npy,Npy-dpknxh)Cl (2). 1 and 2 were identified from the results of their elemental analyses, spectroscopic and electrochemical properties. X-ray structural analysis on single crystals of 1 and 2 grown from CH3CN solutions and fac-Re(CO)3(κ2-Npy,Npy-dpknxh)Cl·DMSO (3) grown from a DMSO solution of 2 confirmed their identities. Spectrophotometric titrations of protophilic solutions of 2 with protophilic solutions of NaBX4 (X = H or F) divulged inter-conversion between the high- and low-energy ILCT transitions of 2 and its solvated complex. Substrates in low concentrations can be detected and determined using protophilic solutions of 2. Electrochemical measurements on 1 and 2 disclosed irreversible redox transformations leading to decomposition of 1 and 2 following the first electron transfer.