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Speciation Behavior of Copper(II) Acetate in Simple Organic Solvents – Revealing the Effect of Trace Water
Author(s) -
Tsybizova Alexandra,
Ryland Bradford L.,
Tsierkezos Nikos,
Stahl Shan S.,
Roithová Jana,
Schröder Detlef
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201400036
Subject(s) - chemistry , copper , electrospray ionization , inorganic chemistry , aqueous solution , heterolysis , redox , catalysis , ion , organic chemistry
Copper(II) acetate is frequently used as a catalyst for bond‐forming reactions in organic synthesis. Unlike aqueous solutions, in which complete heterolysis to CuOAc + (aq) and AcO – (aq) prevails at low concentrations, it is clear that copper(II) acetate shows a large degree of aggregation in typical organic solvents. Here, the speciation behavior of Cu(OAc) 2 in organic solvents is probed by electrospray ionization mass spectrometry (ESI‐MS), which reveals an extensive clustering of copper acetate species to form ions of the general composition [Cu n (X) 2 n –1 ] + and [Cu n (X) 2 n +1 ] – (X = OAc and OCH 3 ), along with (solvated) monomeric species such as [Cu(OAc)(CH 3 OH) n ] + . The ESI‐MS measurements are complemented by solution‐phase studies of Cu(OAc) 2 by electron paramagnetic resonance spectroscopy, which support an extensive aggregation of Cu(OAc) 2 in organic solvents. Collisional experiments reveal that either simple degradation or redox processes can be observed, depending on the coordinative saturation of the copper clusters. The formation of the copper clusters can be efficiently suppressed by contamination of the organic solvents by a small amount of water.