The solvatochromic shift observed for a monooxo-Mo dithiolene complex containing both fully oxidized (dithione, Dt0) and fully reduced (ene-1,2-dithiolate(2-), Dt2-) dithiolene ligands has been successfully modeled using ab initio implicit solvent calculations. The crystal structure of MoO(tdt)(iPr2Dt0) (tdt = toluene-3,4-dithiol, iPr2Dt0 = N,N’-diisopropylpiperzine-2,3-dithione) was optimized in the gas phase and all 179 solvents, of differing dielectric constants, in the Gaussian16 software package to produce 180 unique structures. TD-DFT calculations on optimized structures were performed in various organic solvents and a clear relationship between Dt0 ligand fold angle (along the S●●●S vector) and LL’CT energy was observed. Solvents with larger dielectric constants decrease ligand fold angle which increases coplanarity between donor and acceptor ligands. Flattening of the Dt0 fold angle facilitates charge transfer and results in the bathochromic shift observed in the absorption spectrum.

Tuning geometric structure with PCM-DFT optimization calculations: A method for modeling solvatochromism in an electronically asymmetric monooxo-mo dithiolene complex

ACS Spring Meeting 2021

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