Study of Electronic and Vibrational Structures of Reduced, Neutral, and Oxidized Ni₃(dpa)₄X₂ Using Density Functional Theory and Raman Spectroscopy

Abstract

The electronic and vibrational structures of trinickel metal string complexes [Ni3(dpa)4X2]1–,0,1+ (X = Cl, NCS) were investigated using both theoretical calculations and spectroscopic methods. We used the density functional theory (DFT) method B3LYP*-D3, including less exact exchange energy and the van der Waals interaction of metal ions, to obtain the geometries and vibrational structures, which were found to be in excellent agreement with the experimental data. The ground state of Ni3(dpa)4X2 is an antiferromagnetic (AF) singlet state, and the next state is a quintet state, which was detected using temperature-dependent Raman spectroscopy under a magnetic field. The vibrational structure of the quintet state is nearly identical to that of the AF state, according to the measured Raman spectra, except that the stretching of Ni–Cl is blue-shifted from 282.5 cm–1 in the AF state to 283.8 cm–1 in the quintet state. Two oxidized Ni3 complexes were found to have [Ni3]7+ cores, the doublet [Ni3(dpa)4]3+ without axial ligands and the quartet [Ni3(dpa)4X2]+. Complex [Ni3(dpa)4X2]−, which was produced from a reduction reaction by gold nanoparticles at room temperature, consists of a quartet state as the ground state and a doublet state lying nearby.

Thermoinduced Metal‐to‐Metal Charge Transfer in Trinuclear Metal String Complex Ru2M(dpa)4Cl2 (M=Ni, Cu, dpa=Dipyridylamido)

“…All geometry optimizations and spectra calculations were performed using the Gaussian 16 package [23] . The modified hybrid functional B3LYP*‐D3 was employed because the calculated Raman spectra resulting from this method agreed with the experimental spectra for some trinuclear HMSCs [24,25] . In these calculations, 15 % of Hartree‐Fock term and the unrestricted methods were used for the HMSCs.…”

Electronic states and vibrational structures of sym‐ and unsym‐Co3(dipyridylamine)4Cl2 using temperature‐controlled Raman and surface‐enhanced Raman spectroscopy

“…Both s‐ and u‐geometries were optimized using the GAUSSIAN package. [ 20 ] The B3LYP*‐D3 method was employed in the Co 3 system because the agreement in both the optimized geometries and the vibrational frequencies of Ni 3 (dpa) 4 Cl 2 with the experimental data was better than that of the BP86 and B3LYP methods. [ 21 ] B3LYP*‐D3 includes a less exchange integral and the correction method D3 for van der Waals interaction between metal ions.…”

Theoretical Studies on the Structures of Metal String Complexes Crn(L)4Cl2 (n = 3, 5, 7; L = Oligo-α-Pyridylamide) under the Effect of an Electric Field

“…Since the first report on the synthesis and structural characterization of [Cu 3 (dpa) 4 Cl 2 ] was published in 1990, a series of studies have been reported by Peng’s group, − Berry’s group, , and Cornia’s group , to develop the structurally similar compounds and to study their molecular structures and physicochemical properties such as magnetic properties, electrical conductivity, and electrochemical properties. Cotton et al found that [Cr 3 (dpa) 4 Cl 2 ] exhibits an asymmetric configuration in benzene and toluene solvents, but in a more polar tetrahydrofuran solvent, it has a symmetric configuration with equal Cr–Cr bonds.…”