Solid-State199Hg MAS NMR Studies of Mercury(II) Thiocyanate Complexes and Related Compounds. Crystal Structure of Hg(SeCN)2

Abstract

The solid-state 199Hg MAS NMR spectra of [Hg(SCN)2], [Hg(SeCN)2], M[Hg(SCN)3], M2[Hg(SCN)4] (M = K, Cs), and K2[Hg3(NCO)8] have been measured, and the (monoclinic) crystal structure of [Hg(SeCN)2] has been determined to assist in the interpretation of the NMR data. The asymmetric unit of Hg(SeCN)2 contains one molecule at an inversion center which shows linear Se−Hg−Se bonding (Hg−Se = 2.4738(10) A, Se−Hg−Se = 180°, Hg−Se−C = 97.5(3)°). Secondary Hg---Se and Hg---N contacts are 3.4246(9) and 2.835(12) A, respectively; this arrangement differs from that in Hg(SCN)2 where there are no secondary Hg---S contacts. A redetermination of the monoclinic crystal structure of K[Hg(SCN)3] is also reported, revealing substantial differences from the earlier work. Spinning sideband analysis has been used to determine the 199Hg shielding anisotropy and asymmetry parameters Δσ and η from the solid-state 199Hg MAS NMR spectra. The effects of changes in the mercury coordination number and of distortion of the coordination ...