TY - JOUR
T1 - Crystal structures of nitronium tetranitratogallate and its reversible solid-state phase transition mediated by nonmerohedral twinning
AU - Colombo, Daniel G.
AU - Young, Victor G
AU - Gladfelter, Wayne L
PY - 2000/10/2
Y1 - 2000/10/2
N2 - Single-crystal X-ray crystallographic analyses of [NO2][Ga(NO3)4] reveal that it undergoes a reversible phase transition without any apparent damage to the crystal during repeated temperature cyclings. The room-temperature, noncentrosymmetric, body-centered tetragonal (I 4), polymorph 1 (a = 9.2774(3) Å, c = 6.1149(2) Å, Z = 2) consists of well-separated nitronium and tetranitratogallate ions. The [Ga(NO3)4]- units exhibit a slightly squashed tetrahedral geometry in which all of the ligands are monodentate. Below approximately 250 K, distortions lower the symmetry to the chiral, body-centered monoclinic nonstandard space group I2. Both components (2a: a = 9.5857(2) Å, b = 5.9399(1) Å, c = 8.9759(2) Å, β = 90.409(1)°, Z = 2. 2b: a = 9.5898(2) Å, b = 5.9376(1) Å, c = 8.9784(1) Å, β = 90.420(1)°, Z = 2) of the nonmerohedrally twinned structure are independently refined and found to be enantiomeric with nearly identical distance and angle parameters. As in the high-temperature polymorph, the cations and anions are well separated. The most notable change involves two of the nitrato ligands in the [Ga(NO3)4]- ions that have become bidendate, causing the molecular structure to distort toward octahedral geometry.
AB - Single-crystal X-ray crystallographic analyses of [NO2][Ga(NO3)4] reveal that it undergoes a reversible phase transition without any apparent damage to the crystal during repeated temperature cyclings. The room-temperature, noncentrosymmetric, body-centered tetragonal (I 4), polymorph 1 (a = 9.2774(3) Å, c = 6.1149(2) Å, Z = 2) consists of well-separated nitronium and tetranitratogallate ions. The [Ga(NO3)4]- units exhibit a slightly squashed tetrahedral geometry in which all of the ligands are monodentate. Below approximately 250 K, distortions lower the symmetry to the chiral, body-centered monoclinic nonstandard space group I2. Both components (2a: a = 9.5857(2) Å, b = 5.9399(1) Å, c = 8.9759(2) Å, β = 90.409(1)°, Z = 2. 2b: a = 9.5898(2) Å, b = 5.9376(1) Å, c = 8.9784(1) Å, β = 90.420(1)°, Z = 2) of the nonmerohedrally twinned structure are independently refined and found to be enantiomeric with nearly identical distance and angle parameters. As in the high-temperature polymorph, the cations and anions are well separated. The most notable change involves two of the nitrato ligands in the [Ga(NO3)4]- ions that have become bidendate, causing the molecular structure to distort toward octahedral geometry.
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U2 - 10.1021/ic0002418
DO - 10.1021/ic0002418
M3 - Article
AN - SCOPUS:0034596832
SN - 0020-1669
VL - 39
SP - 4621
EP - 4624
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 20
ER -