sup 13 C CP/MAS NMR studies of the stereochemical nonrigidity of titanium tetracyclopentadienyl in the solid state
- Univ. of Oxford (England)
Variable-temperature {sup 13}C CP/MAS NMR spectroscopy of Ti({eta}-C{sub 5}H{sub 5}){sub 2}({sigma}-C{sub 5}H{sub 5}){sub 2} has shown that sigmatropic rearrangement of the {eta}-cyclopentadienyl rings occurs for the molecule in the crystalline state. Magnetization-transfer experiments at 165 K are consistent with (1,2) shifts being the main pathway for the rearrangement, but there is evidence for the possibility of (1,3) shifts as a minor pathway. These measurements, in conjunction with spectral line-shape analysis in the exchange broadening regime, have been used to estimate Arrhenius activation parameters for (1,2) shifts of E{sub a} = 33.2 {plus minus} 1.0 kJ mol{sup {minus}1} and A = 2.9 {times} 10{sup 10} s{sup {minus}1}. The activation barrier is similar to that suggested by solution NMR studies, implying that control of the rearrangement is principally by electronic factors. In contrast to the results of solution NMR studies, only at the highest temperature (369 K) accessible before thermal decomposition of the solid intervenes is there evidence that {sigma}/{eta}-cyclopentadienyl ligand functionality interchange may be significant on the NMR time scale.
- OSTI ID:
- 5234275
- Journal Information:
- Journal of the American Chemical Society; (United States), Vol. 113:2; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
Similar Records
Synthesis and characterization of Cp{sub 2}Zr(CH(Me)(6-ethylpyrid-2-yl)) (CO){sup +}, a d{sup 0} metal alkyl carbonyl complex. Coordination chemistry of the four-membered azazirconacycle Cp{sub 2}Zr({eta}{sup 2}-C,N-CH(Me)(6-ethylpyrid-2-yl)){sup +}
{sup 113}Cd shielding tensors of monomeric cadmium compounds containing nitrogen donor atoms. 3. CP/MAS studies on five-coordinate cadmium complexes having N{sub 3}X{sub 2} (X = H, N, O, and S) donor atoms
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
TITANIUM COMPLEXES
NUCLEAR MAGNETIC RESONANCE
ARRHENIUS EQUATION
EXPERIMENTAL DATA
MEASURING METHODS
STEREOCHEMISTRY
COMPLEXES
DATA
EQUATIONS
INFORMATION
MAGNETIC RESONANCE
NUMERICAL DATA
RESONANCE
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties