High-pressure, low-temperature, single-crystal neutron diffraction study of deuterated and hydrogenous ammonium hexaaquacopper(II) sulfate (Tutton's salt): a pressure-switchable Jahn-Teller distortion

• Published in: Journal of the American Chemical Society Vol. 115; no. 24; pp. 11304 - 11311
• Main Authors: Simmons, Charles J, Hitchman, Michael A, Stratemeier, Horst, Schultz, Arthur J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-12-1993
• Subjects: 400100 - Analytical & Separations Chemistry; 400201 - Chemical & Physicochemical Properties; AMMONIUM COMPOUNDS; COHERENT SCATTERING; COMPILED DATA; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; COPPER COMPOUNDS; COPPER SULFATES; CRYSTALLOGRAPHY; DATA; DEUTERIUM COMPOUNDS; DIFFRACTION; Electron states; Exact sciences and technology; Exchange interactions; HYDRATES; HYDROGEN COMPOUNDS; INFORMATION; Inorganic compounds; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; JAHN-TELLER EFFECT; Level splitting and interactions; Metal complexes; NEUTRON DIFFRACTION; Neutron diffraction and scattering; NUMERICAL DATA; OXYGEN COMPOUNDS; Physics; PRESSURE DEPENDENCE; SCATTERING; Single-crystal and powder diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; SULFATES; SULFUR COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; X-RAY DIFFRACTION; Transition element complexes; Inorganic compounds; Molecular structure; Neutron diffraction; Experimental study; Jahn-Teller effect; Temperature range 0013-0065 K; High pressure; Ammonium sulfates; Electronic structure; Aqua complex; Intramolecular hydrogen bond; Copper complexes; Crystal structure
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00077a032

The first example of a pressure-induced Jahn-Teller distortion switch has been observed in a single-crystal time-of-flight neutron diffraction study of the Tutton salt (ND[sub 4])[sub 2][Cu(D[sub 2]O)[sub 6]](SO[sub 4])[sub 2] at T = 15 K, P = 1 bar (D[sub L]) and T = 15 K, P = 1.5 kbar (D[sub H]). Also studied was the hydrogenous salt (NH[sub 4])[sub 2][Cu(H[sub 2]O)[sub 6]](SO[sub 4])[sub 2] at T = 14 K, P = 1.4 kbar (H[sub H]). The unit cell parameters are as follows: D[sub L], a = 9.451(2) [angstrom], b = 12.736(3) [angstrom], c = 6.096(1) [angstrom], [beta] = 107.13(2)[degrees], Z = 2, V = 701.2(3) [angstrom][sup 3], space group = P2[sub 1]/a; D[sub H], a = 9.136(1) [angstrom], b = 12.285(2) [angstrom], c = 6.371(1) [angstrom], [beta] = 106.28(2)[degrees], Z = 2, V = 686.4(2) [angstrom][sup 3], space group = P2[sub 1]/a; H[sub H], a = 9.068(2) [angstrom], b = 12.232(2) [angstrom], c = 6.340(1) [angstrom], [beta] = 106.44(2), Z = 2, V = 674.5(2) [angstrom][sup 3], space group = P2[sub 1]/a. Application of 1.5 kbar of pressure to the deuterated crystal produces a decrease in the lengths of the a and b axes by 0.315(2) and 0.451(4) [angstrom], respectively, whereas the c axis increases by 0.275(1) [angstrom]. Comparison of the D[sub L] and D[sub H] structures shows that the long axis of the Jahn-Teller distortion has switched by 90[degrees], i.e., Cu(1)-O(7) = 2.022(2) and Cu(1)-O(8) = 2.310(2) [angstrom] for D[sub L] vs Cu(1)-O(7) = 2.290(2) and Cu(1)-O(8) = 2.014(2) [angstrom] for D[sub H], so that the D[sub H] and H[sub H] structures are similar. 38 refs., 6 figs., 3 tabs.