Oxalatonickelate

The oxalatonickelates are a class of compounds that contain nickel complexed by oxalate groups. They form a series of double salts, and include clusters with multiple nickel atoms.

formula	name	other names	structure	Remarks	references
bis(oxalato)nickelate (2−)				[1]
Li2[(C2O4)2Ni]•6H2O	dilithium bis(oxalato)nickelate (2−)			cas=112678-94-1 dehydrate 80° decompose 345°	[2]
Na2[(C2O4)2Ni]•3H2O	disodium bis(oxalato)nickelate (2−)			cas=107996-66-5 dehydrates at 85°, decompose over 320°	[3][4]
[NH4]2[(C2O4)2Ni]•3H2O	diammonium bis(oxalato)nickelate (2−)			cas=108559-31-5 dehydrate 180-262° deaminate 262-338 °C	[3][5]
K2[(C2O4)2Ni•2H2O]•4H2O	dipotassium trans-diaquabis(oxalato-O,O')nickelate(II)-water (1/4)	potassium bis oxalate nickel(II) tetrahydrate	monoclinic a=8.647 b=6.627 c=12.118 β=101.58° V=680.3 Z=2 density=2.05 / 2.04	green cas=14244-63-4	[6][7][8][9]
Co[(C2O4)2Ni]•5H2O	cobalt(II)bis(oxalato)nickelate(II)pentahydrate			light pink	[10]
Mn[(C2O4)2Ni]•4H2O	manganese(II)bis(oxalato)nickelate(II)tetrahydrate			light blue	[11]
Cd[(C2O4)2Ni]•4H2O	cadmium(II)bis(oxalato)nickelate(II)tetrahydrate			blue	[10]

Because the Ni²⁺ ion resembles many other divalent metal ions, it can be substituted by them, or substitute for them in other oxalate compounds to form mixed oxalates where the proportions can vary continuously. For example, magnesium nickel oxalate dihydrate.^[12]

References

1. Macintyre, Jane E. (1997). Dictionary of Inorganic Compounds, Supplement 4. CRC Press. p. 453. ISBN 9780412750205. Retrieved 21 April 2016.
2. Saha, H.L.; Mitra, S. (June 1987). "Thermal decomposition reactions of metal carboxylato complexes in the solid state. III. Thermographic and differential thermal studies of metal oxalato, malonato and succinato complexes". Thermochimica Acta. 116: 53–64. doi:10.1016/0040-6031(87)88164-9.
3. Macintyre, Jane E. (1997). Dictionary of Inorganic Compounds, Supplement 4. CRC Press. p. 251. ISBN 9780412750205. Retrieved 21 April 2016.
4. Saha, H.L.; Mitra, S. (January 1987). "Thermal decomposition reactions of metal carboxylato complexes in the solid state. I.". Thermochimica Acta. 109 (2): 331–342. doi:10.1016/0040-6031(87)80029-1.
5. Saha, H.L.; Mitra, S. (March 1987). "Thermal decomposition reactions of metal carboxylato complexes in the solid state". Thermochimica Acta. 112 (2): 275–287. doi:10.1016/0040-6031(87)88284-9.
6. Román, P.; Guzmán-Miralles, C.; Luque, A. (15 July 1993). "Structure of dipotassium trans-diaquabis(oxalato-O,O')nickelate(II)–water (1/4)". Acta Crystallographica Section C. 49 (7): 1336–1339. doi:10.1107/S0108270193000940.
7. Narsimhulu, M.; Raju, B.; Saritha, A.; Narayana Rao, D.; Hussain, K.A. (September 2015). "A new room-temperature ultraviolet emission material: K2[Ni(C2O4)2(H2O)2]·4H2O". Physica B: Condensed Matter. 472: 45–48. doi:10.1016/j.physb.2015.05.019.
8. Macintyre, Jane E. Dictionary of Inorganic Compounds, Supplement 1. CRC Press. p. 45. ISBN 9780412490903. Retrieved 25 April 2016.
9. Macintyre, Jane E. (1997). Dictionary of Inorganic Compounds, Supplement 4. CRC Press. p. 222. ISBN 9780412750205. Retrieved 21 April 2016.
10. Deb, Nidhuban; Baruah, S. D.; Dass, N. N. (2000). "Synthesis, Characterization and Thermal Decomposition of M1[M2(C2O4)2]xH2O (x=5 for M1=Co and x=4 for M1=Cd; M2=Ni)". Journal of Thermal Analysis and Calorimetry. 59 (3): 791–797. doi:10.1023/A:1010153720786.
11. Deb, Nidhuban (July 2005). "Thermal decomposition of manganese(II)bis(oxalato)nickelate(II)tetrahydrate". Journal of Thermal Analysis and Calorimetry. 81 (1): 61–65. doi:10.1007/s10973-005-0746-y.
12. Packter, A.; Omomo, A. (1984). "The coprecipitation of Magnesium Nickel Oxalate Dihydrate Powders (solid solutions) from aqueous solution: Precipitate compositions and Coprecipitate Mechanisms". Crystal Research and Technology. 19 (4): 467–476. doi:10.1002/crat.2170190406.