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(carbamoylthiophonolato)mercury(II) complex, (NEt4)(2)[Hg-(S-2-CH3NHCOC6H4)(4)] (5), were synthesized and characterized by H-1 NMR, IR, Hg-199 NMR, and crystallographic analyses. The bis(carbamoylthiophenolato)mercury complexes 1-3 do not have intramolecular NH center dot center dot center dot 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 center dot center dot center dot S hydrogen bond. A relatively weak NH center dot center dot center dot S hydrogen bond in 5 can be seen in the H-1 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 center dot center dot center dot 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 center dot center dot center dot S hydrogen bond.