Structure- and orientation-dependent magnetic susceptibility of tetramethylammonium nickel nitrite, (CH{sub 3}){sub 4}N[Ni(NO{sub 2}){sub 3}]: An S = 1 one-dimensional Heisenberg antiferromagnet
- Univ. of Florida, Gainesville, FL (United States)
The crystal structure of tetramethylammonium nickel nitrite, (CH{sub 3}){sub 4}N[Ni(NO{sub 2}){sub 3}] (TMNIN), has been determined; space group P{bar 3}m1 with a = b = 9.1029(7) {angstrom}, c = 7.0816(7) {angstrom}, V = 508.18(8) {angstrom}{sup 3} ({mu} = 1.93 mm{sup {minus}1}, d{sub calc} = 1.770 g/cm{sup 3}, Z = 2, Mo K{alpha} ({lambda} = 0.710 73 {angstrom}), T = 298 K). Refinement from 359 reflections with I > 2{sigma}(I) and 45 parameters yielded values for R and wR of 2.50 and 2.82, respectively. The structure consists of infinite chains of Ni{sup 2+} ions with adjacent Ni ions bridged by three cis-{mu}-nitro ligands such that alternate Ni ions are chemically distinct with Ni1 octahedrally coordinated with six nitrite nitrogens, and the adjacent Ni2 octahedrally coordinated with six nitrite oxygens. The tetramethylammonium ions are located in positions along the 3-fold rotation axes and form channels that separate the Ni chains. The intrachain Ni-Ni distance is 3.541 {angstrom} and the interchain separation is 9.1029 {angstrom}. Magnetic susceptibility data are presented from 1.8 to 300 K on a sample of aligned single crystals and yield a nearly isotropic nearest-neighbor exchange, J/k{sub B} {approx} -10 K. From the anisotropy in the g value, a coarse estimate of the axial single ion anisotropy, D, yields D/k{sub B} {approx} 0.5 {+-} 1.2 K. Since TMNIN is an S = 1 one-dimensional Heisenberg antiferromagnet, the implications of the alternating chain structure on the existence of a Haldane gap in this material are discussed. 48 refs., 3 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 98750
- Journal Information:
- Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 11 Vol. 6; ISSN 0897-4756; ISSN CMATEX
- Country of Publication:
- United States
- Language:
- English
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