Nickel(II) chloride (or just nickel chloride) is the chemical compound NiCl2. The anhydroussalt is yellow, but the more familiar hydrate NiCl2·6H2O is green. Nickel(II) chloride, in various forms, is the most important source of nickel for chemical synthesis. The nickel chlorides are deliquescent, absorbing moisture from the air to form a solution. Nickel salts have been shown to be carcinogenic to the lungs and nasal passages in cases of long-term inhalation exposure.[4]
The largest scale production of nickel chloride involves the extraction with hydrochloric acid of nickel matte and residues obtained from roasting refining nickel-containing ores.
Nickel chloride is not usually prepared in the laboratory because it is inexpensive and has a long shelf-life. Heating the hexahydrate in the range 66–133.°C gives the yellowish dihydrate, NiCl2·2H2O.[5] The hydrates convert to the anhydrous form upon heating in thionyl chloride or by heating under a stream of HCl gas. Simply heating the hydrates does not afford the anhydrous dichloride.
The dehydration is accompanied by a color change from green to yellow.[6]
In case one needs a pure compound without presence of cobalt, nickel chloride can be obtained cautiously heating hexaamminenickel chloride:[7]
Structure of NiCl2 and its hydrates
NiCl2 adopts the CdCl2 structure.[8] In this motif, each Ni2+ center is coordinated to six Cl− centers, and each chloride is bonded to three Ni(II) centers. In NiCl2 the Ni-Cl bonds have "ionic character". Yellow NiBr2 and black NiI2 adopt similar structures, but with a different packing of the halides, adopting the CdI2 motif.
In contrast, NiCl2·6H2O consists of separated trans-[NiCl2(H2O)4] molecules linked more weakly to adjacent water molecules. Only four of the six water molecules in the formula is bound to the nickel, and the remaining two are water of crystallization.[8]Cobalt(II) chloride hexahydrate has a similar structure. The hexahydrate occurs in nature as the very rare mineral nickelbischofite.
The dihydrate NiCl2·2H2O adopts a structure intermediate between the hexahydrate and the anhydrous forms. It consists of infinite chains of NiCl2, wherein both chloride centers are bridging ligands. The trans sites on the octahedral centers occupied by aquo ligands.[9] A tetrahydrate NiCl2·4H2O is also known.
Reactions
Nickel(II) chloride solutions are acidic, with a pH of around 4 due to the hydrolysis of the Ni2+ ion.
Coordination complexes
Color of various Ni(II) complexes in aqueous solution. From left to right, [Ni(NH3)6]2+, [Ni(en)3]2+, [NiCl4]2−, [Ni(H2O)6]2+
Most of the reactions ascribed to "nickel chloride" involve the hexahydrate, although specialized reactions require the anhydrous form.
Reactions starting from NiCl2·6H2O can be used to form a variety of nickel coordination complexes because the H2O ligands are rapidly displaced by ammonia, amines, thioethers, thiolates, and organophosphines. In some derivatives, the chloride remains within the coordination sphere, whereas chloride is displaced with highly basic ligands. Illustrative complexes include:
Some nickel chloride complexes exist as an equilibrium mixture of two geometries; these examples are some of the most dramatic illustrations of structural isomerism for a given coordination number. For example, NiCl2(PPh3)2, containing four-coordinate Ni(II), exists in solution as a mixture of both the diamagnetic square planar and the paramagnetic tetrahedral isomers. Square planar complexes of nickel can often form five-coordinate adducts.
NiCl2 is the precursor to acetylacetonate complexes Ni(acac)2(H2O)2 and the benzene-soluble (Ni(acac)2)3, which is a precursor to Ni(1,5-cyclooctadiene)2, an important reagent in organonickel chemistry.
In the presence of water scavengers, hydrated nickel(II) chloride reacts with dimethoxyethane (dme) to form the molecular complex NiCl2(dme)2.[5] The dme ligands in this complex are labile. For example, this complex reacts with sodium cyclopentadienide to give the sandwich compoundnickelocene.
Hexammine nickel chloride complex is soluble when respective cobalt complex is not, which allows for easy separating of these close-related metals in laboratory conditions.
As a precursor to finely divided Ni by reduction with Zn, for the reduction of aldehydes, alkenes, and nitro aromatic compounds. This reagent also promotes homo-coupling reactions, that is 2RX → R-R where R = aryl, vinyl.
As a catalyst for making dialkyl arylphosphonates from phosphites and aryl iodide, ArI:
ArI + P(OEt)3 → ArP(O)(OEt)2 + EtI
NiCl2-dme (or NiCl2-glyme) is used due to its increased solubility in comparison to the hexahydrate.[13]
Application of NiCl2 precatalyst.
Other uses
Nickel chloride solutions are used for electroplating nickel onto other metal items.
Safety
Nickel(II) chloride is irritating upon ingestion, inhalation, skin contact, and eye contact. Prolonged inhalation exposure to nickel and its compounds has been linked to increased cancer risk to the lungs and nasal passages.[4]
References
^ abLide, David S. (2003). CRC Handbook of Chemistry and Physics, 84th Edition. CRC Press. pp. 4–71. ISBN9780849304842.
^ abZumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN978-0-618-94690-7.
^ abGrimsrud, Tom K; Andersen, Aage (2010). "Evidence of carcinogenicity in humans of water-soluble nickel salts". Journal of Occupational Medicine and Toxicology. 5 (1): 7. doi:10.1186/1745-6673-5-7. PMC2868037. PMID 20377901.
^ abWard, Laird G. L. (1972). "Anhydrous Nickel(II) Halides and their Tetrakis(ethanol) and 1,2-Dimethoxyethane Complexes". Inorganic Syntheses. Inorganic Syntheses. Vol. 13. pp. 154–164. doi:10.1002/9780470132449.ch30. ISBN9780470132449.
^Karyakin, Yu.V. (1947). Pure chemicals. Manual for laboratory preparation of inorganic substances (in Russian) (Moscow, Leningrad "State Scientific Technical Publishing of Chemical Literature" ed.). p. 416.
^ abWells, A. F. Structural Inorganic Chemistry, Oxford Press, Oxford, United Kingdom, 1984.
^B. Morosin "An X-ray diffraction study on nickel(II) chloride dihydrate" Acta Crystallogr. 1967. volume 23, pp. 630-634. doi:10.1107/S0365110X67003305
^Gill, N. S. & Taylor, F. B. (1967). "Tetrahalo Complexes of Dipositive Metals in the First Transition Series". Inorganic Syntheses. 9: 136–142. doi:10.1002/9780470132401.ch37. ISBN9780470132401.
^G. D. Stucky; J. B. Folkers; T. J. Kistenmacher (1967). "The Crystal and Molecular Structure of Tetraethylammonium Tetrachloronickelate(II)". Acta Crystallographica. 23 (6): 1064–1070. doi:10.1107/S0365110X67004268.
^Tien-Yau Luh, Yu-Tsai Hsieh Nickel(II) Chloride" in Encyclopedia of Reagents for Organic Synthesis (L. A. Paquette, Ed.) 2001 J. Wiley & Sons, New York. doi:10.1002/047084289X.rn012. Article Online Posting Date: April 15, 2001.
^Cornella, Josep; Edwards, Jacob T.; Qin, Tian; Kawamura, Shuhei; Wang, Jie; Pan, Chung-Mao; Gianatassio, Ryan; Schmidt, Michael; Eastgate, Martin D. (2016-02-24). "Practical Ni-Catalyzed Aryl–Alkyl Cross-Coupling of Secondary Redox-Active Esters". Journal of the American Chemical Society. 138 (7): 2174–2177. doi:10.1021/jacs.6b00250. PMC4768290. PMID 26835704.
External links
Wikimedia Commons has media related to Nickel(II) chloride.
NIOSH Pocket Guide to Chemical Hazards
Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD)
January 07, 2023
nickel, chloride, just, nickel, chloride, chemical, compound, nicl2, anhydrous, salt, yellow, more, familiar, hydrate, nicl2, 6h2o, green, various, forms, most, important, source, nickel, chemical, synthesis, nickel, chlorides, deliquescent, absorbing, moistur. Nickel II chloride or just nickel chloride is the chemical compound NiCl2 The anhydrous salt is yellow but the more familiar hydrate NiCl2 6H2O is green Nickel II chloride in various forms is the most important source of nickel for chemical synthesis The nickel chlorides are deliquescent absorbing moisture from the air to form a solution Nickel salts have been shown to be carcinogenic to the lungs and nasal passages in cases of long term inhalation exposure 4 Nickel chloride structure of hexahydrateAnhydrousNamesIUPAC name Nickel II chlorideOther names Nickelous chloride nickel II salt of hydrochloric acidIdentifiersCAS Number 7718 54 9 Y7791 20 0 hexahydrate Y3D model JSmol Interactive imageChEBI CHEBI 34887 YChemSpider 22796 YECHA InfoCard 100 028 858EC Number 231 743 0KEGG C14711 YPubChem CID 24385RTECS number QR6480000UNII 696BNE976J YT8365BUD85 hexahydrate YUN number 3288 3077CompTox Dashboard EPA DTXSID7040316InChI InChI 1S 2ClH Ni h2 1H q 2 p 2 YKey QMMRZOWCJAIUJA UHFFFAOYSA L YInChI 1 2ClH Ni h2 1H q 2 p 2Key QMMRZOWCJAIUJA NUQVWONBARSMILES Cl Ni ClPropertiesChemical formula NiCl2Molar mass 129 5994 g mol anhydrous 237 69 g mol hexahydrate Appearance yellow brown crystals deliquescent anhydrous green crystals hexahydrate Odor odorlessDensity 3 55 g cm3 anhydrous 1 92 g cm3 hexahydrate Melting point 1 001 C 1 834 F 1 274 K anhydrous 140 C hexahydrate Solubility in water anhydrous 67 5 g 100 mL 25 C 1 87 6 g 100 mL 100 C hexahydrate 123 8 g 100 mL 25 C 1 160 7 g 100 mL 100 C Solubility 0 8 g 100 mL hydrazine soluble in ethylene glycol ethanol ammonium hydroxide insoluble in ammonia nitric acidAcidity pKa 4 hexahydrate Magnetic susceptibility x 6145 0 10 6 cm3 molStructureCrystal structure MonoclinicCoordination geometry octahedral at NiThermochemistryStd molarentropy S 298 107 J mol 1 K 1 2 Std enthalpy offormation DfH 298 316 kJ mol 1 2 HazardsOccupational safety and health OHS OSH Main hazards Very toxic T Irritant Xi Dangerous for the environment N CarcinogenGHS labelling PictogramsSignal word DangerHazard statements H301 H315 H317 H331 H334 H341 H350i H360D H372 H410Precautionary statements P201 P202 P260 P261 P264 P270 P271 P272 P273 P280 P281 P285 P301 P310 P302 P352 P304 P340 P304 P341 P308 P313 P311 P314 P321 P330 P332 P313 P333 P313 P342 P311 P362 P363 P391 P403 P233 P405 P501NFPA 704 fire diamond 300Flash point Non flammableLethal dose or concentration LD LC LD50 median dose 105 mg kg rat oral 3 Safety data sheet SDS Fischer ScientificRelated compoundsOther anions Nickel II fluorideNickel II bromideNickel II iodideOther cations Palladium II chloridePlatinum II chloridePlatinum II IV chloridePlatinum IV chlorideRelated compounds Cobalt II chlorideCopper II chlorideExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa N verify what is Y N Infobox references Contents 1 Production and syntheses 2 Structure of NiCl2 and its hydrates 3 Reactions 3 1 Coordination complexes 3 2 Applications in organic synthesis 3 3 Other uses 4 Safety 5 References 6 External linksProduction and syntheses EditThe largest scale production of nickel chloride involves the extraction with hydrochloric acid of nickel matte and residues obtained from roasting refining nickel containing ores Nickel chloride is not usually prepared in the laboratory because it is inexpensive and has a long shelf life Heating the hexahydrate in the range 66 133 C gives the yellowish dihydrate NiCl2 2H2O 5 The hydrates convert to the anhydrous form upon heating in thionyl chloride or by heating under a stream of HCl gas Simply heating the hydrates does not afford the anhydrous dichloride NiCl 2 6 H 2 O 6 SOCl 2 NiCl 2 6 SO 2 12 HCl displaystyle ce NiCl2 6H2O 6 SOCl2 gt NiCl2 6SO2 12HCl The dehydration is accompanied by a color change from green to yellow 6 In case one needs a pure compound without presence of cobalt nickel chloride can be obtained cautiously heating hexaamminenickel chloride 7 Ni NH 3 6 Cl 2 hexammine nickel chloride 175 200 C NiCl 2 6 NH 3 displaystyle ce overset hexammine atop nickel chloride Ni NH3 6 Cl2 gt 175 200 circ ce C NiCl2 6NH3 Structure of NiCl2 and its hydrates EditNiCl2 adopts the CdCl2 structure 8 In this motif each Ni2 center is coordinated to six Cl centers and each chloride is bonded to three Ni II centers In NiCl2 the Ni Cl bonds have ionic character Yellow NiBr2 and black NiI2 adopt similar structures but with a different packing of the halides adopting the CdI2 motif In contrast NiCl2 6H2O consists of separated trans NiCl2 H2O 4 molecules linked more weakly to adjacent water molecules Only four of the six water molecules in the formula is bound to the nickel and the remaining two are water of crystallization 8 Cobalt II chloride hexahydrate has a similar structure The hexahydrate occurs in nature as the very rare mineral nickelbischofite The dihydrate NiCl2 2H2O adopts a structure intermediate between the hexahydrate and the anhydrous forms It consists of infinite chains of NiCl2 wherein both chloride centers are bridging ligands The trans sites on the octahedral centers occupied by aquo ligands 9 A tetrahydrate NiCl2 4H2O is also known Reactions EditNickel II chloride solutions are acidic with a pH of around 4 due to the hydrolysis of the Ni2 ion Coordination complexes Edit Color of various Ni II complexes in aqueous solution From left to right Ni NH3 6 2 Ni en 3 2 NiCl4 2 Ni H2O 6 2 Most of the reactions ascribed to nickel chloride involve the hexahydrate although specialized reactions require the anhydrous form Reactions starting from NiCl2 6H2O can be used to form a variety of nickel coordination complexes because the H2O ligands are rapidly displaced by ammonia amines thioethers thiolates and organophosphines In some derivatives the chloride remains within the coordination sphere whereas chloride is displaced with highly basic ligands Illustrative complexes include Complex Color Magnetism Geometry Ni NH3 6 Cl2 blue violet paramagnetic octahedral Ni en 3 2 violet paramagnetic octahedralNiCl2 dppe orange diamagnetic square planar Ni CN 4 2 colorless diamagnetic square planar NiCl4 2 10 11 Yellowish green paramagnetic tetrahedral Crystals of hexammine nickel chlorideSome nickel chloride complexes exist as an equilibrium mixture of two geometries these examples are some of the most dramatic illustrations of structural isomerism for a given coordination number For example NiCl2 PPh3 2 containing four coordinate Ni II exists in solution as a mixture of both the diamagnetic square planar and the paramagnetic tetrahedral isomers Square planar complexes of nickel can often form five coordinate adducts NiCl2 is the precursor to acetylacetonate complexes Ni acac 2 H2O 2 and the benzene soluble Ni acac 2 3 which is a precursor to Ni 1 5 cyclooctadiene 2 an important reagent in organonickel chemistry In the presence of water scavengers hydrated nickel II chloride reacts with dimethoxyethane dme to form the molecular complex NiCl2 dme 2 5 The dme ligands in this complex are labile For example this complex reacts with sodium cyclopentadienide to give the sandwich compound nickelocene Hexammine nickel chloride complex is soluble when respective cobalt complex is not which allows for easy separating of these close related metals in laboratory conditions Applications in organic synthesis Edit NiCl2 and its hydrate are occasionally useful in organic synthesis 12 As a mild Lewis acid e g for the regioselective isomerization of dienols dd In combination with CrCl2 for the coupling of an aldehyde and a vinylic iodide to give allylic alcohols For selective reductions in the presence of LiAlH4 e g for the conversion of alkenes to alkanes As a precursor to Brown s P 1 and P 2 nickel boride catalyst through reaction with NaBH4 As a precursor to finely divided Ni by reduction with Zn for the reduction of aldehydes alkenes and nitro aromatic compounds This reagent also promotes homo coupling reactions that is 2RX R R where R aryl vinyl As a catalyst for making dialkyl arylphosphonates from phosphites and aryl iodide ArI ArI P OEt 3 ArP O OEt 2 EtI dd NiCl2 dme or NiCl2 glyme is used due to its increased solubility in comparison to the hexahydrate 13 Application of NiCl2 precatalyst Other uses Edit Nickel chloride solutions are used for electroplating nickel onto other metal items Safety EditNickel II chloride is irritating upon ingestion inhalation skin contact and eye contact Prolonged inhalation exposure to nickel and its compounds has been linked to increased cancer risk to the lungs and nasal passages 4 References Edit a b Lide David S 2003 CRC Handbook of Chemistry and Physics 84th Edition CRC Press pp 4 71 ISBN 9780849304842 a b Zumdahl Steven S 2009 Chemical Principles 6th Ed Houghton Mifflin Company p A22 ISBN 978 0 618 94690 7 Nickel metal and other compounds as Ni Immediately Dangerous to Life or Health Concentrations IDLH National Institute for Occupational Safety and Health NIOSH a b Grimsrud Tom K Andersen Aage 2010 Evidence of carcinogenicity in humans of water soluble nickel salts Journal of Occupational Medicine and Toxicology 5 1 7 doi 10 1186 1745 6673 5 7 PMC 2868037 PMID 20377901 a b Ward Laird G L 1972 Anhydrous Nickel II Halides and their Tetrakis ethanol and 1 2 Dimethoxyethane Complexes Inorganic Syntheses Inorganic Syntheses Vol 13 pp 154 164 doi 10 1002 9780470132449 ch30 ISBN 9780470132449 Pray A P 1990 Anhydrous Metal Chlorides Inorganic Syntheses 28 321 2 doi 10 1002 9780470132593 ch80 ISBN 9780470132593 Karyakin Yu V 1947 Pure chemicals Manual for laboratory preparation of inorganic substances in Russian Moscow Leningrad State Scientific Technical Publishing of Chemical Literature ed p 416 a b Wells A F Structural Inorganic Chemistry Oxford Press Oxford United Kingdom 1984 B Morosin An X ray diffraction study on nickel II chloride dihydrate Acta Crystallogr 1967 volume 23 pp 630 634 doi 10 1107 S0365110X67003305 Gill N S amp Taylor F B 1967 Tetrahalo Complexes of Dipositive Metals in the First Transition Series Inorganic Syntheses 9 136 142 doi 10 1002 9780470132401 ch37 ISBN 9780470132401 G D Stucky J B Folkers T J Kistenmacher 1967 The Crystal and Molecular Structure of Tetraethylammonium Tetrachloronickelate II Acta Crystallographica 23 6 1064 1070 doi 10 1107 S0365110X67004268 Tien Yau Luh Yu Tsai Hsieh Nickel II Chloride in Encyclopedia of Reagents for Organic Synthesis L A Paquette Ed 2001 J Wiley amp Sons New York doi 10 1002 047084289X rn012 Article Online Posting Date April 15 2001 Cornella Josep Edwards Jacob T Qin Tian Kawamura Shuhei Wang Jie Pan Chung Mao Gianatassio Ryan Schmidt Michael Eastgate Martin D 2016 02 24 Practical Ni Catalyzed Aryl Alkyl Cross Coupling of Secondary Redox Active Esters Journal of the American Chemical Society 138 7 2174 2177 doi 10 1021 jacs 6b00250 PMC 4768290 PMID 26835704 External links Edit Wikimedia Commons has media related to Nickel II chloride NIOSH Pocket Guide to Chemical Hazards Linstrom Peter J Mallard William G eds NIST Chemistry WebBook NIST Standard Reference Database Number 69 National Institute of Standards and Technology Gaithersburg MD Retrieved from https en wikipedia org w index php title Nickel II chloride amp oldid 1103177740, wikipedia, wiki, book, books, library,
