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.

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. XI. Molecular structure of tetraammine{(±)-pentane-2,4-diamine)cobalt(III) dithionate

1981 ◽  
Vol 34 (1) ◽  
pp. 45 ◽  
Author(s):  
TW Hambley ◽  
CJ Hawkins ◽  
JA Palmer ◽  
MR Snow
Keyword(s):  
Conformational Analysis ◽  
Chelate Ring ◽  
Minimum Energy ◽  
Chair Conformation ◽  
Energy Difference ◽  
Boat Conformation ◽  
Anisotropic Temperature ◽  
Strain Energy Minimization ◽  
Temperature Factors ◽  
Good Agreement

The crystal structure of tetraammine{(�)-pentane-2,4-diamine}cobalt(III) dithionate dihydrate [Co{(�)-ptn}(NH3)4] (S2O6)1.5,2H2O has been determined by X-ray structure analysis. The crystals are triclinic with the space group Pī, with a 11.43, b 11.65, c 7.78 �, α 100.48�, β 105.95�, and γ 75.95�. The structure has been refined by least-squares methods with anisotropic temperature factors to an R value of 0.043 for 2654 reflections. The six-membered diamine chelate ring has a skew-boat conformation in which the two methyl groups are in equatorial orientations. A strain- energy-minimization calculation for the complex reveals an energy difference of 8.3 kJ mol-l between the preferred skew-boat conformation and the chair conformation. The calculated minimum-energy geometry for the skew-boat conformation is in good agreement with the observed structure for the chelate ring in the dithionate salt. The lH N.M.R. spectra of this complex and other complexes of the chiral isomer of pentane-2,4-diamine are discussed in terms of the observed structures and the conformational analysis.

The Dichloroplatinum(II) and Dichloropalladium(II) Complexes of 1,4-Diazacycloheptane: Preparative, Structural and Conformational Studies

1996 ◽  
Vol 49 (12) ◽  
pp. 1301 ◽  
Author(s):  
GW Allen ◽  
ECH Ling ◽  
LV Krippner ◽  
TW Hambley
Keyword(s):  
Crystal Structures ◽  
Chelate Ring ◽  
Chair Conformation ◽  
Monoclinic Space Group ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Membered Chelate Ring ◽  
Alternative Conformation

The preparation and purification of [Pt( hpip )Cl2] and [Pd( hpip )Cl2] ( hpip = homopiperazine = 1,4-diazacycloheptane) are described. Crystal structures of [Pt( hpip )Cl2] and [Pd( hpip )Cl2] have been determined by X-ray diffraction methods and refined to R values of 0.023 (932 F) and 0.023 (948 F). The crystals of [Pt( hpip )Cl2] are orthorhombic, space group Pbcm , a 7.7019(8), b 9.8080(12), c 12.1944(14) Ǻ, and those of [Pd( hpip )Cl2] are monoclinic, space group P21/m, a 6.1001(9), b 11.527(2), c 6.458(I) Ǻ, β 106.30(2)°. The seven- membered rings of the ligands in both complexes adopt boat-like conformations in which the five- membered chelate ring has an eclipsed N-C-C-N group and the six- membered chelate ring adopts a chair conformation. Molecular mechanics methods were used to investigate whether this conformation was a crystallographic artefact but it was found to be real. An alternative conformation in which the six-membered chelate ring adopts a skew-boat conformation was also investigated. It was found to be less stable than the conformation observed in the crystal structures, but to a degree that depends on whether non-bonded interactions involving the metal atom were included or not.

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

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

The Crystal and Molecular-Structure of Two Complexes of Cobalt(III) With Pentaaza Macrocyclic Ligands Chloro (1,4,7,10,14-pentaazacycloheptadecane)cobalt(III) Bromide Chloride Hydrate [Co(C12H29N5)Cl] (Br0.33Cl1.67)H2O and Bromo(1,4,7,11,15-pentaazacyclooctadecane)cobalt(III) Bromide [Co(C13H31N5)Br]Br2

1987 ◽  
Vol 40 (5) ◽  
pp. 829 ◽  
Author(s):  
NF Curtis ◽  
GJ Gainsford ◽  
P Osvath ◽  
DC Weatherburn
Keyword(s):  
Chelate Ring ◽  
Octahedral Geometry ◽  
Distorted Octahedral Geometry ◽  
Boat Conformation ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Membered Chelate Ring ◽  
Ligand Interactions ◽  
Chloride Hydrate ◽  
Chelate Rings

The structures of the compounds chloro (1,4,7,10,14-pentaazacycloheptadecane) cobalt(III) bromide chloride hydrate, [Co( chad )Cl] ( Br0.33Cl1.67)H2O(1) and bromo (1,4,7,11,15-pentaazacyclooctadecane) cobalt(III) bromide, [Co( coad )Br]Br2(2),have been determined by X-ray diffractometry. [Compound (1) orthorhombic, space group P bac, a 1208.5, b 2305.5, c 1318.9 pm, Z 8, R 0.056, Rw 0.071 for 1943 reflections. Compound (2), triclinic, space group P1, a 930.8, b 953.5, c 1120.3pm, α 84.60,β 398.82, γ 105.26�, Z 2, R 0.045, RW0.054 for 4821 reflections.] The compounds have structures with two ( chad ) or three ( coad ) six-membered chelate rings in the equatorial (N4) plane, but with different configurations of the chiral nitrogen centres ; chad : 1SR , 4SR, 7RS, 10RS, that is, with only the NH group at the junction of the two six-membered chelate rings on the same side of the N4 plane as the axial nitrogen; coad : 1 RS, 7SR, 11 SR, 15RS, that is, with NH groups of the central six-membered chelate ring on the same side of the N4 plane as the axial nitrogen, and the others on the opposite side. The chad compound has regular octahedral geometry, with one chair and one boat conformation six-membered chelate ring. The coad compound has distorted octahedral geometry, with long Co-N distances in the N4 plane, attributed to intra-ligand interactions.

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