Syntheses and characterization of titanium malonato and amino acid complexes: [Ti(cp∗)2(OOCCH2NMe2)] – The first structurally characterized α-amino acid titanium(III) complex

The reaction of [Ti(cp∗)2(BTMSA)] (1) (cp∗ = η5-C5Me5, BTMSA = bis(trimethylsilyl)acetylene) with malonic acids ((HOOC)2CR2, R = H, Me) and N,N-dimethylglycine resulted in the formation of titanium(IV) dicarboxylato complexes [Ti(cp∗)2{(OOC)2CR2}] (R = H, 2; R = Me, 3) and an α-amino acid titanium(III) complex [Ti(cp∗)2(OOCCH2NMe2)] (4). The identities of complexes 2–4 were confirmed by microanalysis, 1H and 13C NMR spectroscopy (2, 3), ESI-MS and CID experiments (2, 3) as well as by ESR and magnetic measurements (μeff = 1.81, 298 K) for 4. Single X-ray diffraction analyses of 2 and 4 exhibited monomolecular complexes in which the titanium atom is distorted tetrahedrally coordinated by two η5-C5Me5 rings and by the chelating bound malonato-κ2O,O′ (2) and N,N-dimethylglycinato-κ2O,O′ ligand (4).

Titanium(IV) malonato and titanium(III) α-amino acid complexes ([Ti(cp∗)2{(OOC)2CR2}] (cp∗ = η5-C5Me5, R = H, 2; R = Me, 3) and [Ti(cp∗)2(OOCCH2NMe2)] (4)) were obtained by the reaction of [Ti(cp∗)2(BTMSA)] (BTMSA = bis(trimethylsilyl)acetylene) (1) with the corresponding malonic acid or N,N-dimethylglycine. The complexes were characterized by NMR spectroscopy and ESI-MS (2, 3) and ESR and magnetic measurements (4) as well as by single X-ray diffraction analysis (2, 4), see as an example the Figure.Figure optionsDownload as PowerPoint slide