Abstract
When [Re(CO)5Cl] was allowed to react with di-2-pyridyl ketone semicarbazone hydrochloride (dpksc.HCl) in refluxing toluene, fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] was isolated. The identity of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] was elucidated from the results of its elemental analysis and confirmed using a number of spectroscopic measurements. Spectroscopic measurements done on non-aqueous solvents divulged sensitivity of fac-[Re(CO)3(κ2-N, N-dpksc)Cl] to changes in its surroundings. 1H NMR studies revealed significant solvent dependence as manifested by the chemical shift variations; the exchange of the amine protons with solvent deuterium in CDCl3 and d6-acetone; the temperature dependence of the chemical shifts of the amine and amide protons and insignificant temperature dependence of the aromatic proton. The electronic absorption spectra of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] measured on non-aqueous solvents disclosed two high energy intra-ligand charge transfer (ILCT) transitions. Optical measurements performed on protophilic solutions of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] in the presence of bases and acids showed the appearance and disappearance of a low energy ILCT electronic transitions and established reversible inter-conversion between fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] and its conjugate base, fac-[Re(CO)3(κ2-N,N-dpksc-H)Cl]-. Thermo-optical measurements done on protophilic solutions of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] disclosed the absence of thermal acid-base inter-conversion between fac-[Re(CO)3(κ2- N,N-dpksc)Cl] and fac-[Re(CO)3(κ2-N,N-dpksc-H)Cl] - and established reversible electronic transfer between the high energy electronic transitions of fac-[Re(CO)3(κ2-N, N-dpksc)Cl]. Optosensing measurements done on protophilic solutions of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] showed acids and bases in concentrations as low as 1.00 × 10-10 M can be detected and determined using protophilic solutions of of fac-[Re(CO)3(κ 2-N,N-dpksc)Cl]. Electrochemical measurements on dmf solutions of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] showed irreversible electrochemical redox process and electrochemically generated product waves pointing to the instability of fac-[Re(CO)3(κ2-N,N- dpksc)Cl] to redox transformations.
Original language | English (US) |
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Pages (from-to) | 118-125 |
Number of pages | 8 |
Journal | Journal of Molecular Structure |
Volume | 1032 |
DOIs | |
State | Published - Jan 30 2013 |
Keywords
- Di-2-pyridyl ketone semicarbazone
- Electrochemistry
- Rhenium
- Sensors
- Spectroscopy
- Synthesis
ASJC Scopus subject areas
- Analytical Chemistry
- Spectroscopy
- Organic Chemistry
- Inorganic Chemistry