Simonkolleite

Zinc chloride hydroxide monohydrate

Names
IUPAC name Zinc chloride hydroxide monohydrate
Other names Tetrabasic zinc chloride hydrate Basic zinc chloride Zinc hydroxychloride Zinc oxychloride Micronutrients TBZC
Identifiers
CAS Number	12167-79-2
Properties
Chemical formula	Zn5(OH)8Cl2·H2O
Molar mass	551.88
Appearance	White crystalline solid
Density	3.3 g/cm3
Melting point	oF( oC)
Solubility in water	Insoluble in water, pH 6.9 measured by EPA method SW846-9045
Solubility	Insoluble in organic solvents
Structure
Crystal structure	Hexagonal
Coordination geometry	Octahedral and Tetrahedral
Hazards
Safety data sheet	[1]
NFPA 704	0 1 0
Flash point	Non-flammable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Zinc chloride hydroxide monohydrate is a zinc hydroxy compound with chemical formula Zn₅(OH)₈Cl₂·H₂O. It is often referred to as tetrabasic zinc chloride (TBZC), basic zinc chloride, zinc hydroxychloride, or zinc oxychloride. It is a colorless crystalline solid insoluble in water. Simonkolleite has been shown to be a desirable nutritional supplement for animals.

The naturally occurring mineral form, simonkolleite, was described as a new mineral in 1985 for samples collected at Richelsdorf, Germany. It is a rare secondary mineral formed by weathering of zinc-bearing slag, and is associated with native zinc, hydrocerussite, diaboleite, zincite and hydrozincite. It is named after Werner Simon and Kurt Kolle, Mineral collectors of Cornberg, near Michelsdorf who submitted the samples for investigation. Simonkolleite is frequently found as a corrosion product of Zn-bearing metals.

Simonkolleite is rhombohedral, space group R3m. There are two crystallographically distinct zinc sites in Simonkolleite, both of which are fully occupied by zinc. The Zn(1) site is coordinated by six hydroxyl (OH) groups in an octahedral geometry [Zn(OH)₆]. The Zn(2) site is coordinated by three OH groups, and one Cl atom in a tetrahedral geometry [Zn(OH)₃Cl]. The [Zn(OH)₆] octahedra form an edge-sharing dioctahedral sheet similar to that observed in dioctahedral micas. On each site of the vacant octahedron, a [Zn(OH)₃Cl] tetrahedron is attached to three anions of the sheet and points away from the sheet. Intercalated between adjacent sheets are interstitial water (H₂O) groups. The sheets are held together by hydrogen bonding from OH groups of one sheet to Cl anions of adjacent sheets, and to interstitial H₂O groups. The [Zn(OH)₆] octahedra have four long equatorial bonds (at 2.157 Å) and two short apical bonds (at 2.066 Å). This apical shortening is a result of the bond-valence requirements of the coordinating OH groups and the connectivity of polyhedra in the structure. The equatorial OH groups [O(1)H] are coordinated by two Zn(1) cations and one Zn(2) cation, whereas the apical OH groups [O(2)H] are coordinated by three Zn(1) cations. As Zn(1) is six-coordinated and Zn(2) is four-coordinated, the local bond-valence requirements require the Zn(1)-O(1) bonds to be considerably longer than the Zn(1)-O(2) bonds. The [Zn(OH)₃Cl] tetrahedron has three short Zn(2)-O(1) bonds (at 1.950 Å) and one long Zn(2)-Cl bond (2.312 Å) (Figure 1).