Hindered rotation in phosphorus trifluoride substituted trimethylenemethaneirontricarbonyl

Nuclear magnetic resonance spectrometry

“…Calculations of the shielding effect of a freely rotating magnetically anisotropic group (1100) and chemical shifts in hydrocarbons (1101) have been presented. Cross-ring couplings for stereochemical assignments for four-membered rings (1102), conformation determination in paramagnetic metal complexes (1103), free rotation of coordinated tetracyanoethylene (1104), hindered rotation of coordinated phosphorus trifluoride (1105), torsional barriers in ferrocenylcarbonium ions (1106), conformations of alcohol derivatives of tricarbonyl (diene) iron compounds (1107), temperature dependence of diastereotopic methylene protons and methyl groups in 2isopropyl -1 -(dimethyaminomethyl)ferrocene (1108), wideline NMR studies of fluxional organometallic molecules in the solid state (1109) , molecular motion in solid trimethylaminegallane (1110) , conformational studies of bridging carboxylate complexes of palladium(II) and platinum(II) (1111), conformational effects in platinum complexes of methylglycines (1112), and studies of rotational isomers of 2-furanaldehyde (1113) have been reported. Keto-enol tautomerism (1114), tautomerism of nitrogen containing cyclic and acyclic compounds (1115), and geometrical isomerism of /3-diketonate complexes (1116) have been the subjects of extensive reviews.…”

Stereochemical studies of metal carbonylphosphorus trifluoride complexes

“…A final type of ligand rearrangement was discovered in the PFs-substituted complexes of trimethylenemethaneiron tricarbonyl, (TMM)Fe(CO)s. The TMM ligand is an unstable organic intermediate, thought to be a diradical, stabilized by the Fe(CO)s group.33 Phosphorus trifluoride substitutes into the complex photochemically to yield all possible species of the type (TMM)Fe(PF3)*(CO)3-*. 34 The high-resolution infrared spectrum as well as Figure 3. Variable-temperature 19F spectra of TMMFeiPFah.…”

“…At low temperatures, the spectrum broadens, then sharpens to a more complex pattern due to three types of protons in a 1:1:1 ratio. 34 The process most probably responsible, for this behavior can be seen by viewing the molecule down the iron-methane carbon axis (Figure 2). It is apparent that the methylene protons have different positions relative to the PF3 group, and hence are no longer chemically equivalent.…”