Nickel compounds
Nickel tetracarbonyl was the first pure metal carbonyl produced, and is unusual in its volatility.
Nickel forms simple binary compounds with non metals including halogens, chalcogenides, and pnictides.
Nickel ions can act as a cation in salts with many acids, including common oxoacids.
Most of the common salts of nickel are green due to the presence of hexaaquanickel(II) ion, Ni(H2O)62+.
In order to show magnetic properties the nickel atoms have to be close enough together in the solid structure.
Nickel(II) fluoride NiF2 is yellow, crystallising in the rutile structure and can form a trihydrate, NiF2·3H2O.
[3] With four bromide atoms, nickel(II) forms a series of salts called tetrabromonickelates.
[6] Non-stoichiometric compounds of nickel with phosphorus, arsenic and antimony exist, and some are found in nature.
The substances with fixed composition include nickel aluminide (NiAl) melting at 1638° with hexagonal structure.
[24] Nickel hexafluorogermanate NiGeF6 has a rosy-tan colour and a hexagonal crystal with a = 5.241 Å unit cell volume is 92.9 Å3.
It can be made by dissolving nickel carbonate, and titanium dioxide in hydrofluoric acid.
[25] They all have hexagonal crystal structure, resembling the similar salts of the other first row transition metals.
[30] Nickel cyanide tetrahydrate Ni(CN)2 · 4 H2O is insoluble in water, but dissolves in aqueous ammonia.
[34] Nickel amide, Ni(NH2)2 is a deep red compound that contains Ni6 clusters surrounded by 12 NH2 groups.
The singly charged ion can be any of the full range of potassium, rubidium, cesium, ammonium (
Nickel can be substituted by other divalent metals of similar sized to make mixtures that crystallise in the same form.
[42] Anhydrous salts of the formula M2Ni2(SO4)3, which can be termed metal nickel trisulfates, belong to the family of langbeinites.
Some minerals are double salts, for example Nickelzippeite Ni2(UO2)6(SO4)3(OH)10 · 16H2O which is isomorphic to cobaltzippeite, magnesiozippeite and zinczippeite, part of the zippeite group.
[17] Nickel can form anions and salts with halogens including the hexafluoronickelates, and tetrafluoronickelates, tetrachloronickelates, tetrabromonickelates and tetraiodonickelates.
[45] Nickel can enter into metal oxygen clusters with other high oxidation state elements to form polyoxometalates.
These may stabilize higher oxidation states of nickel, or show catalytic properties.
[53] Nickel bis(dimethylglyoximate), an insoluble red solid is important for gravimetric analysis.
Some hydrogenase enzymes contain a nickel-iron cluster as an active site in which the nickel atom is held in place by cysteine or selenocysteine.
[61] Mixed cluster carbonyl anions like [Cr2Ni3(CO)16]2−, [Mo2Ni3(CO)16]2− and [W2Ni3(CO)16]2− [Mo These lewis base ligands include triphenylphosphine, triphenoxyphosphine, trimethoxyphosphine, tributylphosphine, triethoxyphosphine, triethylisonitrolphosphine, triphenylarsine, and triphenylstibine. [64] tetrasulfur tetranitride when reduced with nickel carbonyl makes Ni[N2S2H]2 also coloured dark violet. At nickel the plane of the molecule is bent, however the connection to the ring has aromatic character. [65] A hexavalent nickel complex, Ni(BeCp)6, has been synthesized, and aromaticity has also been calculated to contribute to its stability. [Ni2(μ3−OEt)2(μ−OEt)8Sb4(OEt)6] Heteroleptic bitmetallic ethoxides have more than one variety of alkoxy group, e.g. Ni[(μ−OPri)(μ−OBut)Al(OBut)2]2 which is a purple solid. With cyclohexane as well, pale blue Ni(NO2)NO is produced with nitrous oxide as a side product.
