10.1021/jp983507t.s001 Daniel B. Lawson Daniel B. Lawson Roger L. DeKock Roger L. DeKock Geometry and Electronic Structure of Titanacycloalkenes American Chemical Society 1999 NRT analysis Vibrational frequencies TZV BLYP carbon atoms bond electron delocalization CTiC plane ab initio techniques B 3LYP levels h 2 TiC 2 H 2 H 2 TiC 2 H 2 MP RHF TiC 4 ring resonance theory H 2 TiC 4 H 4 LANL 2DZ pseudopotential Electronic Structure HTiC 3 H 3 AIM isovalent cyclobutadiene HTiC 5 H 5 C 2 v symmetry 1999-02-27 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Geometry_and_Electronic_Structure_of_Titanacycloalkenes/3727395 A number of titanacycloalkenes, H<sub>2</sub>TiC<sub>2</sub>H<sub>2</sub>, HTiC<sub>3</sub>H<sub>3</sub>, H<sub>2</sub>TiC<sub>4</sub>H<sub>4</sub>, and HTiC<sub>5</sub>H<sub>5</sub>, have been studied using ab initio techniques. Vibrational frequencies were computed at the RHF, MP2, BLYP, and B3LYP levels. Both a LANL2DZ pseudopotential and an all-electron TZV basis set was used for each method. The electronic structure of the systems of interest is characterized in terms of natural resonance theory (NRT) and the atoms in molecules (AIM) analysis. All rings are planar except for titanabenzene, HTiC<sub>5</sub>H<sub>5</sub>. H<sub>2</sub>TiC<sub>2</sub>H<sub>2</sub> has <i>C</i><sub>2</sub><i><sub>v</sub></i> symmetry and has single Ti−C bonds. HTiC<sub>3</sub>H<sub>3</sub>, unlike the isovalent cyclobutadiene and silacyclobutadiene, has <i>C</i><sub>2</sub><i><sub>v</sub></i> symmetry and shows significant electron delocalization. In H<sub>2</sub>TiC<sub>4</sub>H<sub>4</sub> the TiC<sub>4</sub> ring is planar with equivalent single Ti−C bonds and has <i>C</i><sub>2</sub><i><sub>v</sub></i> symmetry. HTiC<sub>5</sub>H<sub>5</sub> has a boat-shaped geometry where the angle between the CTiC plane and the plane formed by the neighboring four carbon atoms is nearly 90°. AIM analysis isolates a weak critical point between Ti and the para-C atom, and NRT analysis confirms the weak bonding interaction.