Hypervalent benzophenones

Evgeniya P. Doronina (1) , Valery F. Sidorkin (1) , Elena F. Belogolova (1) , Viatcheslav Jouikov (2)

1 SB RAS - Siberian Branch of the Russian Academy of Sciences
2 ISCR - Institut des Sciences Chimiques de Rennes

Benzophenones (BPs) of the type 2-R-BP and 2,2'-R-BP, carrying silicon-or germanium-containing substituents R (R = EY2X; E = Si, Ge; Y = H, Me, F, Cl; X = H, F, Cl, OTf) at one or at two ortho-positions of the arene rings, were theoretically designed. Among 26 compounds considered, only 10 monosubstituted 2-R-BP and 5 bis-substituted 2,2'-R-BP (in hexane and DMSO solutions) belong to the first examples of hypervalent benzophenones. In these "true" chelates, the length of the O -> E dative contact (which has a covalent component, according to the AIM analysis) is in the range of 2.0-2.4 angstrom, and the degree of pentacoordination of E is higher than 40%. In these compounds, a significant planarization of the benzophenone part occurs, compared to the initial BP. The TD-DFT calculations suggest the UV spectral properties of the hypervalent BPs to differ fundamentally from those of BP. For the "true" chelates 2-R-BP and 2,2'-R-BP, there is a well pronounced trend of a change of the coordination O -> E contact strength along with the difference between the wavelengths of their first high-intensity band and the pi pi* band of the unsubstituted BP. (c) 2018 Elsevier B.V. All rights reserved.

Keywords: B3PW91; TD-DFT; AIM analysis; Benzophenone; Hypervalent silicon and germanium

Domains: Chemical Sciences

Evgeniya P. Doronina, Valery F. Sidorkin, Elena F. Belogolova, Viatcheslav Jouikov. Hypervalent benzophenones. Journal of Organometallic Chemistry, 2018, 858, pp.89-96. ⟨10.1016/j.jorganchem.2018.01.024⟩. ⟨hal-01737375⟩