The first determination of the energy difference between solid-state conformers by x-ray diffraction. 1. The crystal structure of the pseudo-Jahn-Teller complex (nitrito)bis(2,2'-bipyridyl)copper(II) nitrate at 20, 100, 165 and 296 K and of its isostructural zinc(II) analog at 295 K. 2. The possibility of using x-ray diffraction to characterize adiabatic potential energy surfaces and relative ligand strengths Academic Article uri icon

abstract

  • The first determination of the energy difference (A£) between solid-state conformers by X-ray diffraction is reported for the pseudo-Jahn-Teller complex [Cu(bpy)2(0N0)]N03; X-ray data were collected at 20, 100, 165, and 296 K. By invoking an adiabatic potential energy surface consisting of two nonequivalent ground-state minima and by applying Boltzmann statistics to it, AE could be determined (77 cm-1) from the temperature variation of the structure of the CuN402chromophore. The crystal structure of the isostructural and orbitally nondegenerate [Zn(bpy)2(0N0)]N03complex was also determined, at 295 K. Both complexes crystallize in the monoclinic space group Plxfn with Z = 4. The unit cell parameters are a = 11.067 (2) k,b = 12.014 (3) A, c = 14.855 (7) A, (3 = 100.01 (3)°, V= 1945 (1) A34, dcM= 1.653 gem’3, T = 20 K;a = 11.168(4)A,b= 11.945 (5) k,c = 14.909 (6) k, (3 = 99.32 (3)°, V= 1962 (1) A3, calcd= 1.638 gem’3, T= 100 K;a = 11.217(2)A,6 = 1 1.936(5)A,c = 14.969(3)A,0 = 99.14(2)°,1979(2)A3,dcM= 1.624 gcm”3, 7= 165 K; a = 11.225 (2) A, b = 12.035 (5) A, c = 15.109 (5) A, 0 = 99.55 (2)°, V = 2013 (2) A3, calcd= 1.597 g cm”3, T = 296 K for [Cu(bpy)2(ONO)]N03and a = 11.292 (3) A, b = 11.962 (4) A, c = 15.384 (5) A, 0 = 101.16 (2)°, V = 2039 (1) A3, 22< 7=296 K) reflections for [Cu(bpy)2(0N0)]N03and 2185 (> 3a7 = 295 K) for [Zn(bpy)2(ONO)]N03gave the following RuR2, and GOF (goodness-of-fit) values: 0.037, 0.028, 1.44; 0.044, 0.032, 1.39; 0.046, 0.076, 2.35; 0.046, 0.053, 1.30; and 0.036, 0.044, 2.90, respectively. The possibility of using low-temperature X-ray diffraction and ESR spectroscopy to determine the energies of the vibronically coupled ground and first-excited electronic states in [Cu(bpy or phen)2(OXO)] Y complexes and to obtain the relative ligand strengths of various OXO” groups (OXO-- CH3C02”, N02“, etc.) is also discussed. © 1987, American Chemical Society. All rights reserved.

author list (cited authors)

  • Simmons, C. J., Hathaway, B. J., Amornjarusiri, K., Santarsiero, B. D., & Clearfield, A.

citation count

  • 57

publication date

  • April 1987