Temperature dependence of the Hammett reaction constant

Abstract

The temperature dependence of the Hammett reaction constant, p, for the hydrogen-exchange reactions of various substituted NN-dimethylanilines has been examined over the temperature range 25-96 "C. Empirical and semiempirical evidence predicts that p should be a linear function of T -l , but the experimental data are equally well correlated by five other arbitrarily selected functions of temperature (T, T i , T2, T-a, and In T ) . Thus a sufficient range in p value has yet to be attained to unequivocally confirm that g is a function of T-l.

Photochemistry of some manganese and chromium dinuclear metal carbonyl complexes in frozen gas matrices at ca. 12 K

“…Complexes (1) and (2) seemed to be the most likely candidates to produce a bridging species, i.e. (13) and (14), forming in the same way as (12) was formed in alkane solution^,'^ as the two metal centres are held in close proximity by the ring linkage. Photolysis of (1) and (2) only resulted in the production of co-ordinatively unsaturated metal centres which did not react with the second fully co-ordinated metal centre of each molecule to form bridged species.…”

Protonated diolefin complexes: Model systems for C;h activation via metal complexation

“…These proceed most likely through electrophilic attack at one of the n-cyclopentadienyl rings (C,H5) leading to a coordinatively unsaturated 16-electron intermediate, followed by fast removal of a proton (Scheme I ) . Protonation with very strong acids may on the other hand proceed by addition at the metal to produce a labile 18-electron [FeH (C,H,),]+ species, detectable by 'H-NMR spectroscopy [4]. There is, however, also evidence for a reversible ring protonation, as slow deuterium incorporation is observed when using deuterated acids.…”