Relation between Intramolecular NH···S Hydrogen Bonds and Coordination Number in Mercury(II) Complexes with Carbamoylbenzenethiol Derivatives

A novel series of bis(carbamoylthiophenolato)mercury(II) complexes, [Hg(S-RNHCOC6H4)2] (1, R = 2-t-Bu; 2, R =
2-CH3; 3, R = 2-C6H5CH2; 4, R = 4-t-Bu), and a tetrakis(carbamoylthiophenolato)mercury(II) complex, (NEt4)2[Hg-(S-2-CH3NHCOC6H4)4] (5), were synthesized and characterized by 1H NMR, IR, 199Hg NMR, and crystallographic
analyses. The bis(carbamoylthiophenolato)mercury complexes 1−3 do not have intramolecular NH···S hydrogen
bonds between the amide NH group and the sulfur atom coordinated to mercury, whereas the tetrakis(thiophenolato)mercury complex 5 does have an intramolecular NH···S hydrogen bond. A relatively weak NH···S hydrogen bond
in 5 can be seen in the 1H NMR spectra and the IR spectra in chloroform and in the solid state. The 199Hg NMR
spectra in bis(carbamoylthiophenolato)mercury complexes 1−4 show a downfield shift, with an increase in the flow
of electrons to mercury(II) from the oxygen atom due to the intramolecular Hg···O bonding interaction. Conversely,
the 199Hg NMR spectra in 5 show a high-field shift with a decrease in the flow of electrons to mercury(II) from the
sulfur atom due to the intramolecular NH···S hydrogen bond.