Structure of the cis monohydrate form of bis(glycinato)copper(II)
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||229.679 g·mol−1|
|Appearance||light blue, flake-like crystals (cis form)|
|Melting point||212 °C (414 °F; 485 K) (decomp.)|
|0.18 g/100 g (0 °C)|
0.52 g/100 g (25 °C)
|Solubility||soluble in DMF, DMSO, pyridine; slightly soluble in ethanol|
|№ 19 (P212121)|
a = 5.21 Å, b = 10.81 Å, c = 13.49 Å
Formula units (Z)
|H302, H315, H319, H400|
|P264, P270, P273, P280, P301+P312, P302+P352, P305+P351+P338, P321, P330, P332+P313, P337+P313, P362, P391, P501|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Copper(II) glycinate (IUPAC suggested name: bis(glycinato)copper(II)) refers to the coordination complex of copper(II) with two equivalents of glycinate, with the formula [Cu(glycinate)2(H2O)x] where x = 1 (monohydrate) or 0 (anhydrous form). The complex was first reported in 1841, and its chemistry has been revisited many times, particularly in relation to the isomerisation reaction between the cis and trans forms which was first reported in 1890.
- Cu(OAc)2 + 2 H2NCH2COOH + x H2O → [Cu(H2NCH2COO)2(H2O)x] + 2 AcOH, x = 0 or 1
Like most amino acid complexes, the glycinate forms a 5-membered chelate ring, with the glycinato ligand serving as a bidentate (κ2Ο,Ν) species. The chelating ligands assume a square planar configuration around the copper atom as is common for tetracoordinate d9 complexes, calculated to be much lower in energy than the alternative tetrahedral arrangement.
Cis and trans isomerism
The unsymmetric nature of the ligand and square planar coordination thereof gives rise to two possible geometric isomers: a cis and a trans form.
Multiple ways of differentiating the geometric isomers exist, an easily accessible one being IR spectroscopy with the characteristic number of C–N, C–O, and CuII–N identifying the ligand configuration. Crystal appearance may also be of some value for isomer indication, though the ultimate diagnostic technique is X-ray crystallography.
- Köse, Dursun Ali; Toprak, Emre; Kaşarcı, Aliye; Avcı, Emre; Avcı, Gülçin Alp; Şahin, Onur; Büyükgüngör, Orhan (2016-07-02). "Synthesis, Spectral, and Thermal Studies of Co(II), Ni(II), Cu(II), and Zn(II)-Glycinato Complexes and Investigation of Their Biological Properties: Crystal Structure of [Cu(µ-gly) 2 (H 2 O)] n". Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry. 46 (7): 1109–1118. doi:10.1080/15533174.2013.801855. ISSN 1553-3174. S2CID 101548954.
- Delf, B. W.; Gillard, R. D.; O'Brien, P. (1979-01-01). "The isomers of α-amino-acids with copper(II). Part 5. The cis and trans isomers of bis(glycinato)copper(II), and their novel thermal isomerization". Journal of the Chemical Society, Dalton Transactions (8): 1301–1305. doi:10.1039/DT9790001301. ISSN 1364-5447.
- Tautermann, Christofer S.; Sabolović, Jasmina; Voegele, Andreas F.; Liedl, Klaus R. (2004-02-01). "Mechanism of the Cis−Trans Isomerization of Bis(glycinato)copper(II)". The Journal of Physical Chemistry B. 108 (6): 2098–2102. doi:10.1021/jp0364497. ISSN 1520-6106.
- Ward, J. D.; Spears, J. W. (1997). "Long-Term Effects of Consumption of Low-Copper Diets with or Without Supplemental Molybdenum on Copper Status, Performance, and Carcass Characteristics of Cattle". Journal of Animal Science. 75 (11): 3057–3065. doi:10.2527/1997.75113057x. PMID 9374323.
- Casari, B. M.; Mahmoudkhani, A. H.; Langer, V. (2004). "A Redetermination of cis-Aquabis(glycinato-κ2N,O)copper(II)". Acta Crystallogr. E. 60 (12): m1949–m1951. doi:10.1107/S1600536804030041.