Factors Affecting the Solid-State Structure and Dimensionality of Mercury Cyanide/Chloride Double Salts, and NMR Characterization of Coordination Geometries

In the reaction of organic monocationic chlorides or coordinatively saturated metal−ligand complex chlorides with
linear, neutral Hg(CN)2 building blocks, the Lewis-acidic Hg(CN)2 moieties accept the chloride ligands to form
mercury cyanide/chloride double salt anions that in several cases form infinite 1-D and 2-D arrays. Thus,
[PPN][Hg(CN)2Cl]·H2O (1), [nBu4N][Hg(CN)2Cl]·0.5 H2O (2), and [Ni(terpy)2][Hg(CN)2Cl]2 (4) contain [Hg(CN)2Cl]22-
anionic dimers ([PPN]Cl = bis(triphenylphosphoranylidene)ammonium chloride, [nBu4N]Cl = tetrabutylammonium
chloride, terpy = 2,2‘:6‘,6‘ ‘-terpyridine). [Cu(en)2][Hg(CN)2Cl]2 (5) is composed of alternating 1-D chloride-bridged
[Hg(CN)2Cl]nn- ladders and cationic columns of [Cu(en)2]2+ (en = ethylenediamine). When [Co(en)3]Cl3 is reacted
with 3 equiv of Hg(CN)2, 1-D {[Hg(CN)2]2Cl}nn- ribbons and [Hg(CN)2Cl2]2- moieties are formed; both form hydrogen
bonds to [Co(en)3]3+ cations, yielding [Co(en)3][Hg(CN)2Cl2]{[Hg(CN)2]2Cl} (6). In [Co(NH3)6]2[Hg(CN)2]5Cl6·2H2O
(7), [Co(NH3)6]3+ cations and water molecules are sandwiched between chloride-bridged 2-D anionic {[Hg(CN)2]5Cl6}n6n-
layers, which contain square cavities. The presence (or absence), number, and profile of hydrogen bond donor
sites of the transition metal amine ligands were observed to strongly influence the structural motif and dimensionality
adopted by the anionic double salt complex anions, while cation shape and cation charge had little effect. 199Hg
chemical shift tensors and 1J(13C,199Hg) values measured in selected compounds reveal that the NMR properties
are dominated by the Hg(CN)2 moiety, with little influence from the chloride bonding characteristics. δiso(13CN)
values in the isolated dimers are remarkably sensitive to the local geometry.