70320-61-5Relevant academic research and scientific papers
The D parameter (zero-field splitting) as a direct measure of structural and electronic effects in localized triplet 1,3-diradicals
Adam, Waldemar,Harrer, Heinrich M.,Heidenfelder, Thomas,Kammel, Thomas,Kita, Fumio,et al.
, p. 2085 - 2090 (2007/10/03)
The zero-field splitting parameter D of the localized triplet diradicals 3-11, generated in a 2-methyltetrahydrofuran (MTHF) glass matrix at 77 K through photochemical deazetation of the corresponding azoalkanes, have been determined by EPR spectroscopy.It is demonstrated that the D parameter depends on structural (changes in the interspin distance d between the spin-bearing sites) effects, owing to differing ring size annelation, as well as electronic (changes in the spin density ρα at the radical sites) effects, i.e.D = f(d, ρα).The Dcalcd values calculated from the theoretical d and ρα values determined by semiempirical MO calculations (PM3) for the triplet diradicals 1-11, correlate well (r2 = 0.961) with the Dexp values determined experimentally.Interestingly, heteroatom substitution at the 4,5-position in the cyclopentane-1,3-diyl moiety causes only a nominal spin delocalization onto the nitrogen atoms for the diradicals 11, which are also classified as localized triplet diradicals.
