
%0 Journal Article
%A Hawkins, CJ 
%A Peachey, RM 
%A Szoredi, CL 
%T Conformational analysis of coordination compounds. VII. Barrier to inversion of five-membered diamine chelate rings by N.M.R
%J Australian Journal of Chemistry
%D 1978/05/01
%V 31
%N 5
%P 973-981
%K 
%R https://doi.org/10.1071/CH9780973
%U https://www.publish.csiro.au/paper/CH9780973 
%X The barriers to &#948; &#8596; &#955; interconversion for the five-membered diamine chelate rings in [M(CO)4(tmen)], where M is chromium(0), molybdenum(0), or tungsten(0) and tmen is N,N,N',N'-tetramethylethane-1,2-diamine, have been determined to be of the order of 39 kJ mol-1 from a band-shape analysis of 13C N.M.R. spectra of the compounds at low temperature. The results have been rationalized in terms of the effects of M-N bond lengths on ring strain energies and have been compared with the barriers determined previously for analogous complexes with coordination numbers of four (tetrahedral) and eight. The equivalent six-membered diamine chelate ring in [Mo(CO)4(tmtn)] was found to have a relatively low barrier to chair-to-chair interconversion with an upper limit of 34 kJ mol-1. 
