Orientational effect of aryl groups on 77Se NMR chemical shifts: experimental and theoretical investigations

Chemistry : a European Journal
Waro NakanishiMasahiko Hada

Abstract

The orientational effect of p-YC6H4 (Ar) on delta(Se) is elucidated for ArSeR, based on experimental and theoretical investigations. The effect is examined in the cases in which Se--CR in ArSeR is either in the Ar plane (pl) or is perpendicular to the plane (pd). 9-(Arylselanyl)anthracenes (1) and 1-(arylselanyl)anthraquionones (2) are employed to establish the effect in pl and pd, respectively. Large upfield shifts are observed for Y=NMe2, OMe, and Me, and large downfield shifts for Y=COOEt, CN, and NO2 in 1, relative to Y=H, as is expected. Large upfield shifts are brought by Y=NMe2, OMe, Me, F, Cl, and Br, and downfield shifts by Y=CN and NO2 in 2, relative to Y=H, with a negligible shift by Y=COOEt. Absolute magnetic shielding tensors of Se (sigma(Se)) are calculated for ArSeR (R=H, Me, and Ph), assuming pl and pd, based on the DFT-GIAO method. Observed characters are well explained by the total sigma(Se). Paramagnetic terms (sigmap(Se)) are governed by (sigmap(Se)xx+sigmap(Se)yy), in which the direction of np(Se) (constructed by 4pz(Se)) is set to the z axis. The main interaction in pl is the np(Se)-pi(C6H4)-pz(Y) type. The Y dependence in pl occurs through admixtures of 4pz(Se) in pi(SeC6H4Y) and pi*(SeC6H4Y), modified by...Continue Reading

Citations

May 15, 2007·Bioinorganic Chemistry and Applications·Satoko Hayashi, Waro Nakanishi
Jun 9, 2016·The Journal of Physical Chemistry. a·Mauro TorselloAntonino Polimeno
Dec 10, 2016·Chemistry : a European Journal·Giovanni RibaudoLaura Orian
Mar 23, 2013·Physical Chemistry Chemical Physics : PCCP·Kateryna SykinaEric Furet
Jul 12, 2017·Chemphyschem : a European Journal of Chemical Physics and Physical Chemistry·Satoko HayashiMasaichi Saito
May 16, 2012·Dalton Transactions : an International Journal of Inorganic Chemistry·Takahito NakaiWaro Nakanishi
Apr 14, 2010·Chemical Reviews·Anna J MukherjeeRaghavan B Sunoj
Jul 15, 2006·The Journal of Organic Chemistry·Satoko HayashiWaro Nakanishi

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