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Title: Anomalous Non-Prussian Blue Structures and Magnetic Ordering of K2MnII[MnII(CN)6] and Rb2MnII [MnII(CN)6]

Abstract

The reaction of Mn{sup II} and KCN in aqueous and non-aqueous media leads to the isolation of three-dimensional (3-D) Prussian blue analogues, K{sub 2}Mn[Mn(CN){sub 6}] (1a-d, 1e, respectively). Use of RbCN forms Rb{sub 2}Mn[Mn(CN){sub 6}] (2). 1 and 2 are isomorphic {l_brace}monoclinic, P2{sub 1}/n: 1 [a = 10.1786(1) {angstrom}, b = 7.4124(1) {angstrom}, c = 6.9758(1) {angstrom}, {beta} = 90.206(1){sup o}]; 2 [a = 10.4101(1) {angstrom}, b = 7.4492(1) {angstrom}, c = 7.2132(1) {angstrom}, {beta} = 90.072(1){sup o}]{r_brace}, with a small monoclinic distortion from the face centered cubic (fcc) structure that is typical of Prussian blue structured materials that was previously reported for K{sub 2}Mn[Mn(CN){sub 6}]. Most notably the average Mn-N-C angles are 148.8{sup o} and 153.3{sup o} for 1 and 2, respectively, which are significantly reduced from linearity. This is attributed to the ionic nature of high spin Mn{sup II} accommodating a reduced M-CN-M{prime} angle and minimizing void space. Compounds 1a,b have a sharp, strong V{sub OH} band at 3628 cm{sup -1}, while 1e lacks a V{sub OH} absorption. The V{sub OH} absorption in 1a,b is attributed to surface water, as use of D{sub 2}O shifts the V{sub OH} absorption to 2677 cm{sup -1}, and that 1a-e are isostructural.more » Also, fcc Prussian blue-structured Cs{sub 2}Mn[Mn(CN){sub 6}] (3) has been structurally [Fm{sub 3}m: a = 10.6061(1) {angstrom}] and magnetically characterized. The magnetic ordering temperature, T{sub c}, increases as K{sup +} (41 K) > Rb{sup +} (34.6 K) > Cs{sup +} (21 K) for A{sub 2}Mn[Mn(CN){sub 6}] in accord with the increasing deviation for linearity of the Mn-N-C linkages [148.8 (K{sup +}) > 153.3 (Rb{sup +}) > 180{sup o} (Cs{sup +})], decreasing Mn(II){hor_ellipsis}Mn(II) separations [5.09 (K{sup +}) < 5.19 (Rb{sup +}) < 5.30 {angstrom} (Cs{sup +})], and decreasing size of the cation (increasing electrostatic interactions). Hence, the bent cyanide bridges play a crucial role in the superexchange mechanism by increasing the coupling via shorter Mn(II){hor_ellipsis}Mn(II) separations, and perhaps enhanced overlap. In addition, the temperature dependent magnetic behavior of K{sub 4}[Mn{sup II}(CN){sub 6}] {center_dot} 3H{sub 2}O is reported.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
DOE - OFFICE OF SCIENCE
OSTI Identifier:
1019909
Report Number(s):
BNL-95755-2011-JA
Journal ID: ISSN 0020-1669; INOCAJ; TRN: US201115%%545
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 49; Journal Issue: 4; Journal ID: ISSN 0020-1669
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; CATIONS; CYANIDES; ELECTROSTATICS; FCC LATTICES; FERROCYANIDES; POTASSIUM COMPOUNDS; SPIN; SURFACE WATERS; national synchrotron light source

Citation Formats

Her, J, Stephens, P, Kareis, C, Moore, J, Min, K, Park, J, Bali, G, Kennon, B, and Miller, J. Anomalous Non-Prussian Blue Structures and Magnetic Ordering of K2MnII[MnII(CN)6] and Rb2MnII [MnII(CN)6]. United States: N. p., 2010. Web. doi:10.1021/ic901903f.
Her, J, Stephens, P, Kareis, C, Moore, J, Min, K, Park, J, Bali, G, Kennon, B, & Miller, J. Anomalous Non-Prussian Blue Structures and Magnetic Ordering of K2MnII[MnII(CN)6] and Rb2MnII [MnII(CN)6]. United States. doi:10.1021/ic901903f.
Her, J, Stephens, P, Kareis, C, Moore, J, Min, K, Park, J, Bali, G, Kennon, B, and Miller, J. Fri . "Anomalous Non-Prussian Blue Structures and Magnetic Ordering of K2MnII[MnII(CN)6] and Rb2MnII [MnII(CN)6]". United States. doi:10.1021/ic901903f.
@article{osti_1019909,
title = {Anomalous Non-Prussian Blue Structures and Magnetic Ordering of K2MnII[MnII(CN)6] and Rb2MnII [MnII(CN)6]},
author = {Her, J and Stephens, P and Kareis, C and Moore, J and Min, K and Park, J and Bali, G and Kennon, B and Miller, J},
abstractNote = {The reaction of Mn{sup II} and KCN in aqueous and non-aqueous media leads to the isolation of three-dimensional (3-D) Prussian blue analogues, K{sub 2}Mn[Mn(CN){sub 6}] (1a-d, 1e, respectively). Use of RbCN forms Rb{sub 2}Mn[Mn(CN){sub 6}] (2). 1 and 2 are isomorphic {l_brace}monoclinic, P2{sub 1}/n: 1 [a = 10.1786(1) {angstrom}, b = 7.4124(1) {angstrom}, c = 6.9758(1) {angstrom}, {beta} = 90.206(1){sup o}]; 2 [a = 10.4101(1) {angstrom}, b = 7.4492(1) {angstrom}, c = 7.2132(1) {angstrom}, {beta} = 90.072(1){sup o}]{r_brace}, with a small monoclinic distortion from the face centered cubic (fcc) structure that is typical of Prussian blue structured materials that was previously reported for K{sub 2}Mn[Mn(CN){sub 6}]. Most notably the average Mn-N-C angles are 148.8{sup o} and 153.3{sup o} for 1 and 2, respectively, which are significantly reduced from linearity. This is attributed to the ionic nature of high spin Mn{sup II} accommodating a reduced M-CN-M{prime} angle and minimizing void space. Compounds 1a,b have a sharp, strong V{sub OH} band at 3628 cm{sup -1}, while 1e lacks a V{sub OH} absorption. The V{sub OH} absorption in 1a,b is attributed to surface water, as use of D{sub 2}O shifts the V{sub OH} absorption to 2677 cm{sup -1}, and that 1a-e are isostructural. Also, fcc Prussian blue-structured Cs{sub 2}Mn[Mn(CN){sub 6}] (3) has been structurally [Fm{sub 3}m: a = 10.6061(1) {angstrom}] and magnetically characterized. The magnetic ordering temperature, T{sub c}, increases as K{sup +} (41 K) > Rb{sup +} (34.6 K) > Cs{sup +} (21 K) for A{sub 2}Mn[Mn(CN){sub 6}] in accord with the increasing deviation for linearity of the Mn-N-C linkages [148.8 (K{sup +}) > 153.3 (Rb{sup +}) > 180{sup o} (Cs{sup +})], decreasing Mn(II){hor_ellipsis}Mn(II) separations [5.09 (K{sup +}) < 5.19 (Rb{sup +}) < 5.30 {angstrom} (Cs{sup +})], and decreasing size of the cation (increasing electrostatic interactions). Hence, the bent cyanide bridges play a crucial role in the superexchange mechanism by increasing the coupling via shorter Mn(II){hor_ellipsis}Mn(II) separations, and perhaps enhanced overlap. In addition, the temperature dependent magnetic behavior of K{sub 4}[Mn{sup II}(CN){sub 6}] {center_dot} 3H{sub 2}O is reported.},
doi = {10.1021/ic901903f},
journal = {Inorganic Chemistry},
issn = {0020-1669},
number = 4,
volume = 49,
place = {United States},
year = {2010},
month = {1}
}