Conformational analysis of coordination compounds. VII. Barrier to inversion of five-membered diamine chelate rings by N.M.R

1978 ◽  
Vol 31 (5) ◽  
pp. 973 ◽  
Author(s):  
CJ Hawkins ◽  
RM Peachey ◽  
CL Szoredi
Keyword(s):  
Low Temperature ◽  
Conformational Analysis ◽  
Shape Analysis ◽  
Coordination Compounds ◽  
Chelate Ring ◽  
Band Shape ◽  
Ring Strain ◽  
Coordination Numbers ◽  
Upper Limit ◽  
Chelate Rings

The barriers to δ ↔ λ 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.

Conformational analysis of coordination compounds. XIV. Proton, carbon-13, cobalt-59 and platinum-195 n.m.r. spectra of six-membered diamine chelaterings

1982 ◽  
Vol 35 (9) ◽  
pp. 1815 ◽  
Author(s):  
CJ Hawkins ◽  
RH Holm ◽  
JA Palmer ◽  
DD Traficante
Keyword(s):  
Conformational Analysis ◽  
Mole Fraction ◽  
Coordination Compounds ◽  
Chelate Ring ◽  
Chair Conformation ◽  
Boat Conformation ◽  
Methyl Group ◽  
Chelate Rings

The conformations adopted by six-membered diamine chelate rings in complexes of the types [Co(NH3),L]3+, [Co(CN)4L]-, [Pt(bpy)L]2+, [Pt(NH3)2L]2+ and [CoL3]3+ have been studied by n.m.r. techniques. The ligands (L) used in the study were meso- and (+)-pentane-2,4-diamine, butane-1,3-diamine, propane-1,3-diamine and 2-methylpentane-2,4-diamine. It has been found that for most complexes of meso-pentane-2,4-diamineth e diequatorial chair conformation predominates, although for the bipyridineplatinum(II) complex it is unclear whether the skew-boat conformation is significantly populated or the chair structure is unusually distorted. For (+)-pentane-2,4-diamine chelates, which normally adopt the skew-boat conformation in octahedral complexes, the chair conformation with an axial and an equatorial methyl group has a mole fraction of 0.5 and 0.7 for the bipyridine- and diammine-platinum(II) complexes, respectively. In tetraammine(butane-1,3- diamine)cobalt(III) the chelate ring is in the chair conformation with the methyl equatorial.

scholarly journals Corrigenda and Addenda to "Conformational Analysis of Coordination Compounds. I. Trisdiamine Cobalt(III) Complexes with Three Six-membered Chelate Rings".

1974 ◽  
Vol 28a ◽  
pp. 248-248 ◽  
Author(s):  
S. R. Niketić ◽  
F. Woldbye ◽  
F. Lindeløv ◽  
Terje Østvold ◽  
Alf Bjørseth ◽  
...  
Keyword(s):  
Conformational Analysis ◽  
Coordination Compounds ◽  
Chelate Rings

Raman band shape analysis of a low temperature molten salt

2003 ◽  
Vol 119 (16) ◽  
pp. 8567-8576 ◽  
Author(s):  
Ary O. Cavalcante ◽  
Mauro C. C. Ribeiro
Keyword(s):  
Low Temperature ◽  
Molten Salt ◽  
Shape Analysis ◽  
Raman Band ◽  
Band Shape

scholarly journals Conformational Analysis of Coordination Compounds. Tris-diamine Cobalt(III) Complexes with Three Six-membered Chelate Rings.

1973 ◽  
Vol 27 ◽  
pp. 621-642 ◽  
Author(s):  
S. R. Niketić ◽  
F. Woldbye ◽  
Christian Rømming ◽  
Steinar Husebye ◽  
P. Klæboe ◽  
...  
Keyword(s):  
Conformational Analysis ◽  
Coordination Compounds ◽  
Chelate Rings

Conformational analysis of coordination compounds. VI. P.M.R. study of diamagnetic five-membered diamine chelate rings

1976 ◽  
Vol 29 (1) ◽  
pp. 33 ◽  
Author(s):  
CJ Hawkins ◽  
RM Peachey
Keyword(s):  
Magnetic Resonance ◽  
Conformational Analysis ◽  
Coordination Compounds ◽  
Proton Magnetic Resonance ◽  
Equatorial Orientation ◽  
Coupling Constant ◽  
Butyl Group ◽  
Magnetic Resonance Spectra ◽  
Chelate Rings

The proton magnetic resonance spectra of a number of coba1t(111), molybdenum(0), chromium(0), platinum(11) and palladium(11) complexes of (R)-propane-1,2-diamine, (S)-3,3-dimethylbutane-1,2- diamine, (RS)-N,N,N',N?-tetramethylpropane-1,2-dime and ethane-1,2-diamine have been analysed and the coupling constant data utilized to calculate the conformational populations for the various complexes. Necessary parameters for the conformational analysis were obtained from a study of tetracyano{(S)-3,3-dimethylbutane-1,2-diamine)cobaltate(111),in which the t-butyl group was assumed to be exclusively in the equatorial orientation. The preparation and resolution of this t-butyl substituted ethane-1,2-diamine are described.

scholarly journals Conformational Analysis of Coordination Compounds. III. Tris-diamine Cobalt(III) and Chromium(III) Complexes with Six-membered Chelate Rings.

1976 ◽  
Vol 30a ◽  
pp. 485-497 ◽  
Author(s):  
Svetozar R. Niketic ◽  
Kjeld Rasmussen ◽  
Flemming Woldbye ◽  
Shneior Lifson ◽  
Jouko Koskikallio
Keyword(s):  
Conformational Analysis ◽  
Coordination Compounds ◽  
Chelate Rings

scholarly journals Conformational Analysis of Coordination Compounds. X. 1H NMR Study of Paramagnetic Five-membered Diamine Chelate Rings.

1978 ◽  
Vol 32a ◽  
pp. 815-832 ◽  
Author(s):  
Clifford J. Hawkins ◽  
Russell M. Peachey ◽  
Stanley F. Dyke ◽  
Alan M. Sargeson
Keyword(s):  
Conformational Analysis ◽  
1H Nmr ◽  
Coordination Compounds ◽  
Nmr Study ◽  
Chelate Rings

scholarly journals Conformational Analysis of Coordination Compounds. II. Dimethyl-substituted Five- and Six-membered Metal Chelate Rings.

1973 ◽  
Vol 27 ◽  
pp. 3811-3816 ◽  
Author(s):  
S. R. Niketić ◽  
F. Woldbye ◽  
Anne-Charlotte Wiehager ◽  
T. Laier ◽  
Wolfgang Nimmich
Keyword(s):  
Conformational Analysis ◽  
Coordination Compounds ◽  
Metal Chelate ◽  
Chelate Rings
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