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The thiophene appended Schiff's base ligand, 1-(2-(thiophen-2-yl)ethylimino)methyl)naphthalene-2-ol (HL) with N,O donor sites has been synthesized by the condensation between 2-hydroxy-1-naphthaldehyde and thiophene-2-ethylamine. The square planar 1:2 complexes of HL having general formula [M(L)2] (M = Ni(1) and Pd(2)) with nickel(II) and palladium(II) have been synthesized and characterized by several spectroscopic techniques. The geometry has been confirmed by single crystal X-ray study for complex 1. The electronic structure and spectral properties of the complexes are interpreted by DFT and TDDFT studies.

The square planar nickel(II) complexes have been synthesized by the reaction of nickel(II) chloride hexahydrate and the in situ condensed thiophene appended Schiff base ligands of thiophene-2-ethylamine with 3,5-dimethyl-2-hydroxybenzaldehyde or 3,5-dichloro-2-hydroxybenzaldehyde for [Ni(L1)2] (1) and [Ni(L2)2] (2) respectively. The complexes have been characterized by several spectroscopic techniques, viz. FT-IR, 1H NMR, absorption and emission spectroscopy. The complexes crystallize in monoclinic crystal system with C2/c space group for 1 and triclinic crystal system with P−1 space group for 2. In complex 1 the nickel sits on an inversion centre with symmetry –x, 2–y, –z. Cyclic voltammgrams of the complexes show quasi-reversible NiII/NiIII oxidation couple along with irreversible NiII/NiI reduction. Electronic structure and spectral properties are well interpreted by DFT and TDDFT calculations.

New rhodium(III)-triphenylphosphine complex, [Rh(PPh3)(L)Cl2](PF6) (1) with thioether containing NNS donor ligand (L) (L = 2-(methylthio)-N-((pyridine-2-yl)methylene)benzenamine) has been synthesized and characterized. The pseudo octahedral geometry of the complex has been confirmed by single crystal X-ray analysis. The electronic structure, redox properties, absorption and emission properties of the complexes have been interpreted by DFT and TDDFT calculations. The complex effectively catalyzed the transfer hydrogenation reaction of ketones in 2-propanol and oxidation of alcohols in presence of NMO.

The article deals with a combined experimental and computational study of rhenium tricarbonyl Schiff base complexes having general formula fac-[ReCl(CO)3(L1/L2)] (1/2) (L1 = N-[(2-pyridyl)methyliden]-α-aminonaphthalene and L2 = N-[(2-pyridyl)methyliden]-β-aminonaphthalene). The complexes fac-[ReCl(CO)3(L1/L2)] (1/2) have been synthesized and characterized by elemental analysis, spectroscopic studies, electrochemistry and X-ray crystal analysis for complex 2. Crystal structure of 2 reveals the facial geometry of the carbonyl ligand and Re is in distorted octahedral environment in the complex. The electronic structure, redox properties, absorption and emission properties have been explained based on DFT and TDDFT calculations. The complexes show MLCT bands at 395–405 nm and emitted at 425–435 nm upon excitation at 310 nm, characterized as ILCT transitions. The complexes exhibit two irreversible ReII/ReI and ReIII/ReII oxidative responses when scanned in the potential range 0.0–2.0 V in cyclic voltammetric studies.