Chromium carboxylates
Chromium carboxylates [Cr(RCOO)2]2 are red diamagnetic solids.
They can be synthesized either by methathesis with chromium chloride in the presence of triethylamine and Lewis bases: 2 CrCl2 + 4 RCO2H + 4 NEt3 + 2 L → [L2Cr(O2CR)2]2 + 4 NEt3H+Cl-
(L = 2-electron donor, H2O, …), or by reaction of chromium metal with corresponding carbonic acid: Cr + 2 RCO2H → ½ [Cr(RCOO)2]2 + 2 H2
Cromium carboxylates have also poor volatility so have been utilised in combustion chemical vapour deposition (CCVD) where precursor is supplied into the CVD chamber dissolved in a solvent and therefore does not require high volatility (example is chromium 2-ethylhexanoate).
Chromium (III) 2-ethylhexanoate Cr[tBu(Et)CHCOO]3
Chromium (III) 2-ethylhexanoate Cr[tBu(Et)CHCOO]3 dissolved in a hydrocarbon solventhas been used for preparation of Cr2O3 layers on mica and glass spheres in a fast circulating fluidised bed by combustion chemical vapour deposition (CCVD); oxygen was used as oxidising agent and carrier gas. The morphology, surface composition and optical properties of the coatings were studied by electron and optical microscopy and elemental analysis. [984]