The crystal and molecular structure of tris(cyclopentadienyl)titanium

Tris(polyalkylcyclopentadienyl) Complexes: The Elusive [(η5‐C5R5)2M(η1‐C5R5)] Structure and Trihapto Cyclopentadienyl Coordination Involving a Methyl Substituent

“…[8] This led to the speculation that [(h 5 [9] and has been theoretically analyzed. [10] Examples include [(h 5 -C 5 H 5 ) 2 Ti(h 2 -C 5 H 5 )], [11] [(h 5 -C 5 H 5 ) 3 Zr-(h 1 -C 5 H 5 )], [12] [13] Hf [14] ),…”

“…Flexibility in the hapticity of cyclopentadienyl ligands is well known [9] and has been theoretically analyzed. [10] Examples include [(h 5 -C 5 H 5 ) 2 Ti(h 2 -C 5 H 5 )], [11] [(h 5 -C 5 H 5 ) 3 Zr-(h 1 -C 5 H 5 )], [12] [(h 5 -C 5 H 5 ) 2 M'(h 1 -C 5 H 5 ) 2 ] (M' = Ti, [13] Hf [14] ), [(h 1 -C 5 Me 4 R) 3 Ga], [15] and polymeric [{(h 5 -C 5 H 5 ) 2 Sc(m-h 1 :h 1 -C 5 H 5 )} x ]. [16] However, it was unclear if such an h 5 to h 1 transformation could occur in these crowded [(h 5 -C 5 Me 5 ) 3…”

A Five‐Coordinate Homoleptic Organotitanium(III) Compound

“…[18] These results departing from simple VSEPR models apply for covalent, essentially nonpolar species. [16,21] The fact that [Ti(C 6 F 5 ) 5 ] 2À in 1 with a distorted TBPY-5 structure more closely resembles a transition state calculated [11] for the anion [TiH 5 ] À than the ground-state structure of this and the aforementioned organometallic compounds could be related to the polarity of the Ti À C bonds caused by the strongly electron withdrawing character of the C 6 F 5 group. [22] It can be concluded that, on a simple VSEPR basis, both the high polarity of the TiÀC bond and the bulkiness of the C 6 F 5 ligand would be expected to favor the TBPY-5 geometry.…”

“…[3] To the best of our knowledge, however, no related [TiR 5 ] 2À species has yet been described containing titanium(iii), a much less studied oxidation state for this metal. In fact, the only well-established homoleptic organotitanium(iii) compounds conform to the [TiR 2 ] + (R = C 5 Me 5 ), [4] [TiR 3 ] (R = C 5 H 5 , [5] CH(SiMe 3 ) 2 ), [6] and [TiR 4 ] À (R = C 6 Cl 5 ) [7] Compound 1 is extremely air sensitive, both in solution and in the solid state. Solid 1 easily explodes under slight mechanical stress, for example, from percussion or a sharp temperature change.…”

“…The crystal and molecular structures of 1 were established by X-ray diffraction. Two crystallographically independent [Ti(C 6 F 5 ) 5 ] 2À anions were found in the asymmetric unit of the crystal but, because of their similarity, we refer to only one of them ( Figure 1). The Ti center is located in a heavily distorted trigonal-bipyramidal (TBPY-5) environment formed by five terminal, s-bonded C 6 F 5 ligands.…”