Detailed magnetic analysis and successful deep-neural-network-based conformational prediction for [VO(dmso)5][BPh4]2.

Pentakis(dimethylsulfoxide-κO)oxidovanadium(iv) bis(tetraphenylborate), [VO(dmso)5][BPh4]2 (dmso: dimethylsulfoxide), was synthesized, and its pseudo-C 4 VO6 coordination geometry was revealed by a single-crystal X-ray method. A novel equation set was obtained for magnetic susceptibility and magnetization of the d1 complexes, considering the axial distortion and the spin-orbit coupling for the 2D free-ion term. The equation set enabled magnetic simulation for significantly symmetry-lowered d1 complexes to obtain the anisotropic g-values and also the excitation energies. In addition, conformational prediction was conducted, using the enumeration results on the basis of the group theory. The dominant conformers were predicted on the basis of the density functional theory (DFT) method, and especially, the conformer in the crystal was successfully predicted by a deep neural network method.

The crystal structure of [Mg(dmso)6][BPh4]2 and the formation mechanism of the conformer on the basis of conformational analysis.

The crystal structure of a new magnesium(ii) complex, [Mg(dmso)6][BPh4]2 (1) (dmso: dimethylsulfoxide), was determined, and the reason for the observed structure was clarified by conformational analysis. For a dmso-ligand arm, three conformations, α, ß, and γ, are possible. The α-arm is the most energetically favourable and is suitable for reducing the steric repulsion between the arms; the ß-arm is less energetically favourable, but can be stabilized by interaction with surroundings (e.g. CHπ interaction); the γ-arm is not energetically favourable, but is effective in reducing the size of the complex cation. From the conformational analysis, the most stable conformer of the [Mg(dmso)6]2+ complex cation was found to be the α6 conformer, and the complex cation in dmso solution was predicted to exist as a mixture of α6, α5ß, and trans-α4ß2 species. On the contrary, in the crystal structure, the trans-ß2γ4 species, considered to be unstable, was observed. From the conformational analysis in the tetraphenylborate surroundings, the trans-ß2γ4 structure was found to become more stable, due to its small size suitable for crystal packing with bulky tetraphenylborate anions.