Polynuclear chloromercurate(II) systems in their chloropyridinium salts.

The chloromercurate(II) salts of 2-, 3- and 4-chloropyridine display a variety of anion stoichiometries and structures, including the rare [Hg(3)Cl(10)](4-) stoichiometry. 2-Chloropyridinium trichloromercurate(II), (I), (C(5)H(5)ClN)[HgCl(3)], monoclinic, P2(1)/n, a = 9.094 (8), b = 18.143 (4), c = 12.902 (3) Å, beta = 106.13 (4) degrees with Z = 8, has the [HgCl(3)](-) stoichiometry, but the anions are infinite chains composed of [HgCl(3)](-), HgCl(2) and Cl(-) moieties linked by longer Hg.Cl contacts. Hydrogen bonds link the cations to the formal Cl(-) ions. Tetrakis(3-chloropyridinium) decachlorotrimercurate(II), (II), (C(5)H(5)ClN)(4)[Hg(3)Cl(10)], monoclinic, P2(1)/n, a = 7.522 (2), b = 28.046 (3), c = 9.165 (2) Å, beta = 105.78 (2) degrees with Z = 2, has the rare [Hg(3)Cl(10)](4-) stoichiometry and contains infinite one-dimensional double-stranded {([HgCl(4)](2-))(2) [HgCl(2)]}(n) anionic chains made up of linear HgCl(2) and distorted [HgCl(4)](2-) entities linked together by longer Hg.Cl contacts. The HgCl(2) moieties are joined by double [HgCl(4)](2-) bridges. Hydrogen bonds link the cations to the sides of the anionic columns. Tetrakis(4-chloropyridinium) decachlorotrimercurate(II), (III), (C(5)H(5)ClN)(4)[Hg(3)Cl(10)], triclinic, P1;, a = 9.907 (3), b = 13.226 (2), c = 7.282 (2) Å, alpha = 84.41 (2), beta = 74.81 (2), gamma = 87.34 (2) degrees with Z = 1, also has the [Hg(3)Cl(10)](4-) stoichiometry and the same type of {([HgCl(4)](2-))(2)[HgCl(2)]}(n) anionic chains that were found in compound (II), but the formal HgCl(2) and [HgCl(4)](2-) moieties are more discrete with much weaker contacts linking the individual units. Bifurcated hydrogen bonds with the cations cross-link the anionic chains to form an infinite two-dimensional network. Second forms of the 3- and 4-chloropyridinium salts were also obtained. 3-Chloropyridinium trichloromercurate(II), (IV), (C(5)H(5)ClN)[HgCl(3)], monoclinic, P2(1)/c, a = 7.243 (5), b = 22.145 (8), c = 12.320 (3) Å, beta = 99.52 (3) degrees with Z = 8, has the [HgCl(3)](-) stoichiometry, but the anions are infinite chains composed of distorted [Hg(2)Cl(6)](2-) moieties. Bifurcated hydrogen bonds from the cations cross-link the anionic chains to form infinite two-dimensional layers. Bis(4-chloropyridinium) hexachlorodimercurate(II), (V), (C(5)H(5)ClN)(2)[Hg(2)Cl(6)], monoclinic, C2/m, a = 13.447 (3), b = 7.534 (2), c = 9.939 (2) Å, beta = 97.48 (2) degrees with Z = 2, contains highly symmetrical discrete [Hg(2)Cl(6)](2-)anions. Bifurcated hydrogen bonds from the cations interconnect the anions to form infinite one-dimensional chains.