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)(2)Cl].H2O (1), [nBu4N][Hg(CN)(2)Cl].0.5 H2O (2), and [Ni(terpy)(2)][Hg(CN)(2)Cl](2) (4) contain [Hg(CN)(2)Cl](2-)(2) anionic dimers ([PPN]Cl = bis(triphenylphosphoranylidene)ammonium chloride, [(Bu4N)-Bu-n]Cl = tetrabutylammonium chloride, terpy = 2,2':6',6"-terpyridine). [Cu(en)(2)][Hg(CN)(2)Cl](2) (5) is composed of alternating 1-D chloride-bridged [Hg(CN)(2)Cl](n-)(n) ladders and cationic columns of [Cu(en)(2)](2+) (en = ethylenediamine). When [Co(en)(3)]Cl-3 is reacted with 3 equiv of Hg(CN)(2), 1-D {Hg(CN)(2)](2)Cl}(n-)(n) ribbons and [Hg(CN)(2)Cl-2](2-) moieties are formed; both form hydrogen bonds to [Co(en)(3)](3+) cations, yielding [Co(en)(3)][Hg(CN)(2)Cl-2]{[Hg(CN)(2)](2)Cl} (6). In [Co(NH3)(6)](2)[Hg(CN)(2)](5)Cl-6.2H(2)O (7), [Co(NH3)(6)](3+) cations and water molecules are sandwiched between chloride-bridged 2-D anionic {[Hg(CN)(2)](5)Cl-6}(6n-)(n) 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. Hg-199 chemical shift tensors and (1)J(C-13,Hg-199) 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. deltaiso((CN)-C-13) values in the isolated dimers are remarkably sensitive to the local geometry.