Ni₃Cl_2.1(OH)_3.9·4H₂O, the Ni Analogue to Mg₃Cl₂(OH)₄·4H₂O

Abstract

For the first time a basic transition-metal hydrate, Ni3Cl2.1(OH)3.9·4H2O, is found to be isostructural to a main-group metal phase, Mg3Cl2.0(OH)4.0·4H2O. The Ni phase was found as crystalline solid in the course of investigations into the formation of basic nickel(II) chloride phases at 25 and 40 °C in alkaline, concentrated nickel(II) chloride solutions. Ni3Cl2.1(OH)3.9·4H2O was characterized by thermal analysis, IR spectroscopy, scanning electron microscopy, and X-ray powder diffraction. The crystal structure was determined from high-resolution laboratory X-ray powder diffraction data. Ni3Cl2.1(OH)3.9·4H2O crystallizes in space group C2/m (12) with Z = 2, a = 14.9575(4) Å, b = 3.1413(1) Å, c = 10.4818(5) Å, β = 101.482(1)°, and V = 482.50(3) Å(3). The main building unit of the structure is an infinite triple chain of edge-linked distorted NiO6 octahedra. These chains are separated by interstitial one-dimensional zigzag chains of disordered Cl(-) ions and H2O molecules. The crystal structures of Ni3Cl2.1(OH)3.9·4H2O and the isostructural magnesium salt hydrate Mg3Cl2(OH)4·4H2O (2-1-4 phase) are compared in detail.

A solid solution series of atacamite type Ni2Mg2−2Cl(OH)3

“…Their hydroxides crystallize in the same, brucite type lattice [26] and form a complete solid solutions series [27]. A recently synthesized basic nickel chloride hydrate was found to be isostructural to a related magnesium phase [28]. Furthermore the crystal structures of "β-Ni 2 Cl(OH) 3 " and "β-Mg 2 Cl(OH) 3 " are expected to be analogous [1] and each phase can be synthesized using similar conditions [10,11].…”

Phase Formation and Solubilities in the Ternary System Ni(OH)2–NiCl2–H2O at 25 and 200 °C

“…In addition, some aspects of the crystal structure are unique for nickel(II) chloride hydroxides or nickel(II) chloride hydrates. In Ni 3 Cl(OH) 5 · 4H 2 O, nickel is exclusively coordinated by oxygen atoms (hydroxide ions and water molecules), whereas in the crystal structures of NiCl 2 · x H 2 O ( x = 2, 4, 6), chloride ions are completely and in nickel(II) chloride hydroxides, at least partially integrated into the coordination sphere of nickel. Neither an examination of the difference Fourier map nor a refinement of the site occupancy factor of the coordinating oxygen atoms pointed to the presence of chloride within the coordination sphere of nickel in the crystal structure of Ni 3 Cl(OH) 5 · 4H 2 O.…”

“…This transformation was complete in 3.0 and 4.0 molal NiCl 2 solution after 1 year, whereas in the resulting solids from 2.0 and 5.0 molal NiCl 2 a trace of residual β‐Ni(OH) 2 could be detected. The presence of small amounts of poorly crystalline β‐Ni(OH) 2 in addition to Ni 3 Cl 2+ x (OH) 4– x · 4H 2 O could hardly be detected by powder X‐ray diffraction, as the most intense 001 reflection of β‐Ni(OH) 2 , with d = 4.6060 Å [≡ 19.3° 2 θ (Cu‐ K α 1 )], usually overlaps with the –202 reflection of Ni 3 Cl 2+ x (OH) 4– x · 4H 2 O, with d = 4.6673 Å [≡ 19.0° 2 θ (Cu‐ K α 1 ); see Figure S4 in the Supporting Information]. However, as the position of the OH stretching mode of β‐Ni(OH) 2 (3635 cm –1 ) differs from related bands in the IR spectrum of Ni 3 Cl 2+ x (OH) 4– x · 4H 2 O (3622, 3611, 3582, 3515 cm –1 ), the presence of a small amount of poorly crystalline β‐Ni(OH) 2 in addition to Ni 3 Cl 2+ x (OH) 4– x · 4H 2 O could be detected by IR spectroscopy (see Figure S5 in the Supporting Information).…”

Ni3Cl2+x(OH)4–x·2H2O: Structural, Thermal, Spectral, and Magnetic Properties in Dependence of the Chloride Content

“…In contrast, Ni 3 Cl 2.82 (OH) 3.18 · 2H 2 O (Figure 1, green line) shows additional, sharp reflections (e.g., at 13.7, 16.1, and 19.9° 2 θ ). These additional reflections do not match the powder patterns of possible impurities [Ni 2 Cl(OH) 3 , NiCl 2 x (OH) 2–2 x (ss‐type OH),48 Ni 3 Cl 2.1 (OH) 3.9 · 4H 2 O,47 β‐Ni(OH) 2 ,40 NiCl 2 · x H 2 O ( x = 0, 2, 4, 6) [44–46,50] ] that could emerge during the synthesis of Ni 3 Cl 2.82 (OH) 3.18 · 2H 2 O. In addition, some reflections show clear, but unsystematic shifts (e.g., at 20.4, 21.4, and 25.5° 2 θ ).…”

“…Owing to their similar chemical properties in aqueous solutions and comparable divalent cation radii,39 the formation of isostructural hydroxides40 and analogous metal chloride hydrates (MCl 2 · x H 2 O, x = 2, 4, 6) showing similar crystal structures,41–46 strong interactions between magnesium chloride hydroxides and nickel(II) ions are expected. In the course of our systematic investigations into the interactions of heavy‐metal ions with magnesium chloride hydroxides, a series of related divalent nickel salts, NiCl(OH) (1‐1‐0), NiCl 2 x (OH) 2–2 x ss‐type OH [(1+ a )‐(1‐ a )‐0], Ni 2 Cl(OH) 3 (3‐1‐0), Ni 3 Cl 2.1 (OH) 3.9 · 4H 2 O (1.95‐1.05‐4), have been synthesized, characterized, and their crystal structures solved 47–49. Each nickel(II) chloride hydroxide phase was found to be analogous to the related magnesium compound in terms of phase composition and crystal structure.…”