A linear relationship between the Ceq-Os-Os-Ceq dihedrals and the Os-Os bond distances was observed on a series of diosmium complexes, Os2(u-O2CR)2(CO)6-n(P(p-tolyl)3)n (n = 0, 1 or 2 and the carboxylate group = formate, acetate, propionate or benzoate), however, the origin of this relationship remains unclear. No clear pattern related to neither P(p-tolyl)3 ligands number noor the bridging ligands basicity (pKa) that would explain this linear behavior. A comprehenive understanding on this pattern yields better understanding between the geometries and electronic properties of dinuclear paddlewheel complexes, whose important applications range from anticancer agents and photocatalysts. Preliminary calculations generated a trend similar to the experimental plot, where the calculated Os-Os distance appears inversely correlated with the dihedrals. The geometry of the system requires a fixed relationship between the O-Os-Os-O dihedral angle, O-Oobserved, Os-O, Os-Os, and Os-Os-O. Due to the consistency of the O-Oobserved and Os-O across different complexes, only Os-Os-O is considered as another major factor involved in the relationship. Further optimization was performed by applying constraint on Os-Os, dihedral and Os-Os-O angles. In our result, for a given complex, stepping either of the Os-Os or dihedral through a set of values produces a linear response to another. Due to the fact that the Os-Os-O acts as a buffer, two different slopes obtained, and this indicates that the dihedral appears to dominate the relationship over the Os-Os distance. This result was then confirmed by solid-state calculations, which simulates the effect of the periodic lattice.

Strucutral investigations of diosimum complexes: The intrisic relationship between their geometric and electronic properties

ACS Spring 2022

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