Synthesis and Crystal Structure of Lanthanum(III)
Iodomercurate(II) Complexes with frame0-Caprolactam

A. V. Tikhomirovaa, E. V. Peresypkinab, A. V. Virovetsb, and T. G. Cherkasovaa

a Kuzbass State Technical University, ul. Vesennyaya 28, Kemerovo, 650000 Russia

b Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia

Received May 2, 2012

Abstract—The X-ray diffraction study of the crystalline products of the reaction between potassium tet-
raiodomercurate(II), -caprolactam, and lanthanum(III) nitrate at a ratio of 3 : 16 : 2 in an aqueous solution has
shown the presence of the following three new crystalline compounds: [LaCpl8]2[HgI4]3 (I), [LaCpl8][HgI4]I3
(II), and [LaCpl7(H2O)]2[HgI4]2[Hg2I6] (III), where Cpl is -caprolactam -C6H11NO. Compounds I and II
crystallize in tetragonal crystal system, space groups P42/n and frame1, respectively. For compound I, a =
18.59320(10) Å, c = 19.5782(3) Å, V = 6738.32(12) Å3, Z = 2, and calc = 2.067 g/cm3. For compound II, a =
13.2245(10) Å, c = 20.0310(3) Å, V = 3503.17(6) Å3, Z = 2, calc = 2.022 g/cm3. The crystals of compound III
are monoclinic (space group P21/n, a = 20.1202(6) Å, b = 14.0569(4) Å, c = 46.3228(12) Å, = 93.4770(10),
V = 13077.3(6) Å3, Z = 4, calc = 2.274 g/cm3). [La(Cpl)8]2[Hg2I6]3 (IV), a new double ionic complex salt, has
also been synthesized and studied by X-ray diffraction. The crystals of compound IV are triclinic (space group
frame2 a = 12.5021(3) Å, b = 14.6436(3) Å, c = 21.4695(4) Å, = 84.2300(10), = 87.2230(10), =
74.9970(10), V = 3776.30(14) Å3, Z = 1, calc = 2.452 g/cm3). All complexes have a dicrete ionic structure, and
the nearest surrounding of a La atom is distorted square-prismatic or trigonal-dodecahedral. The crystal packing
of cations is distorted face-centered cubic (I and II) or body-centered cubic (III and IV) with anions located in
its cavities.

DOI: 10.1134/S0036023613050215

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