Titanium complexes, reaction with carbon dioxide

Imido zwitterionic titanium complexes, Ti=NAr[CH3B(C6F5)3], undergo reaction with carbon dioxide to give isocyanates and symmetrical carbodiimides via a ligand metathesis... 

Very related to the titanium chemistry described above are experiments with resembling molybdenocene complexes. If the molybdenum-diphenyl-acetylene complex Cp2Mo(PhC=CPh) is used as starting material, no C-C linkage reaction takes place with carbon dioxide. Instead, a crystalline solid was isolated whose x-ray proved the formation of a molybdenum-carbon dioxide complex [85] (Equation 15). 

Also, switterionic titanium-imide complexes mediate the reaction of carbon dioxide with primary amines to give the corresponding isocyanates and symmetrical carbodiimides via a ligand metathesis reaction . 

An interesting linkage reaction between ethene and carbon dioxide is reported in titanium chemistry [1]. Bis(pentamethylcyclopenta-dieny1(ethene)titanium(II) reacts rapidly with one equivalent of carbon dioxide in a toluene solution at -78°C affording a titanalac-tone in yields up to 80 % (Equation 1). The complex is thermally robust both as a solid and in solution but decomposes slowly upon exposure to visible light. 

P. G. Morgan Franklin Institute) There seemed to be a temperature rise where your strontium carbonate itself decomposes. In other words, you superimposed some of the complexities of decomposition of strontium carbonate onto further reaction with titanium dioxide, and your supply of strontium ions and oxygen ions is continuously changing as decomposition proceeds. I think you could do one of two things to simplify this. You could either carry out the reaction between the carbonate and oxide in a temperature regime where the carbonate itself would not otherwise decompose, or you could just start with strontium oxide and titanium oxide to simplify things. 

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