TY - JOUR
T1 - Bulk and molecular compressibilities of organic-inorganic hybrids [(CH3)4N]2MnX4 (X = Cl, Br); Role of intermolecular interactions
AU - Barreda-Argüeso, Jose Antonio
AU - Nataf, Lucie
AU - Rodríguez-Lazcano, Yamilet
AU - Aguado, Fernando
AU - González, Jesús
AU - Valiente, Rafael
AU - Rodríguez, Fernando
AU - Wilhelm, Heribert
AU - Jephcoat, Andrew P.
N1 - Publisher Copyright:
© 2014 American Chemical Society.
PY - 2014/10/6
Y1 - 2014/10/6
N2 - This work reports an X-ray diffraction, X-ray absorption, and Raman spectroscopy study of [(CH3)4N]2MnX4 (X = Cl, Br) under pressure. We show that both compounds share a similar phase diagram with pressure. A P21/c monoclinic structure describes precisely the [(CH3)4N]2MnCl4 crystal in the 0.1-6 GPa range, prior to crystal decomposition and amorphization, while [(CH3)4N]2MnBr4 can be described by a Pmcn orthorhombic structure in its stability pressure range of 0-3 GPa. These materials are attractive systems for pressure studies since they are readily compressible through the weak interaction between organic/inorganic [(CH3)4N+/MnX42-] tetrahedra through hydrogen bonds and contrast with the small compressibility of both tetrahedra. Here we determine the equation-of-state (EOS) of each crystal and compare it with the corresponding local EOS of the MnX42- and (CH3)4N+ tetrahedra, the compressibility of which is an order and 2 orders of magnitude smaller than the crystal compressibility, respectively, in both chloride and bromide. The variations of the Mn-Cl bond distance obtained by extended X-ray absorption fine structure and the frequency of the totally symmetric ν1(A1) Raman mode of MnCl42- with pressure in [(CH3)4N]2MnCl4 allowed us to determine the associated Grüneisen parameter (γloc = 1.15) and hence an accurate local EOS. On the basis of a local compressibility model, we obtained the Grüneisen parameters and corresponding variations of the intramolecular Mn-Br and C-N bond distances of MnBr42- (γloc = 1.45) and (CH3)4N+ (γloc = 3.0) in [(CH3)4N]2MnBr4.
AB - This work reports an X-ray diffraction, X-ray absorption, and Raman spectroscopy study of [(CH3)4N]2MnX4 (X = Cl, Br) under pressure. We show that both compounds share a similar phase diagram with pressure. A P21/c monoclinic structure describes precisely the [(CH3)4N]2MnCl4 crystal in the 0.1-6 GPa range, prior to crystal decomposition and amorphization, while [(CH3)4N]2MnBr4 can be described by a Pmcn orthorhombic structure in its stability pressure range of 0-3 GPa. These materials are attractive systems for pressure studies since they are readily compressible through the weak interaction between organic/inorganic [(CH3)4N+/MnX42-] tetrahedra through hydrogen bonds and contrast with the small compressibility of both tetrahedra. Here we determine the equation-of-state (EOS) of each crystal and compare it with the corresponding local EOS of the MnX42- and (CH3)4N+ tetrahedra, the compressibility of which is an order and 2 orders of magnitude smaller than the crystal compressibility, respectively, in both chloride and bromide. The variations of the Mn-Cl bond distance obtained by extended X-ray absorption fine structure and the frequency of the totally symmetric ν1(A1) Raman mode of MnCl42- with pressure in [(CH3)4N]2MnCl4 allowed us to determine the associated Grüneisen parameter (γloc = 1.15) and hence an accurate local EOS. On the basis of a local compressibility model, we obtained the Grüneisen parameters and corresponding variations of the intramolecular Mn-Br and C-N bond distances of MnBr42- (γloc = 1.45) and (CH3)4N+ (γloc = 3.0) in [(CH3)4N]2MnBr4.
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U2 - 10.1021/ic501854g
DO - 10.1021/ic501854g
M3 - Article
AN - SCOPUS:84907833769
VL - 53
SP - 10708
EP - 10715
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 19
ER -