Department of Physics & Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA.
Inorg Chem. 2010 Feb 15;49(4):1524-34. doi: 10.1021/ic901903f.
The reaction of Mn(II) and KCN in aqueous and non-aqueous media leads to the isolation of three-dimensional (3-D) Prussian blue analogues, K(2)Mn[Mn(CN)(6)] (1a-d, 1e, respectively). Use of RbCN forms Rb(2)Mn[Mn(CN)(6)] (2). 1 and 2 are isomorphic {monoclinic, P2(1)/n: 1 [a = 10.1786(1) A, b = 7.4124(1) A, c = 6.9758(1) A, beta = 90.206(1)(o)]; 2 [a = 10.4101(1) A, b = 7.4492(1) A, c = 7.2132(1) A, beta = 90.072(1)(o)]}, 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(2)Mn[Mn(CN)(6)]. Most notably the average Mn-N-C angles are 148.8 degrees and 153.3 degrees for 1 and 2, respectively, which are significantly reduced from linearity. This is attributed to the ionic nature of high spin Mn(II) accommodating a reduced M-CN-M' angle and minimizing void space. Compounds 1a,b have a sharp, strong nu(OH) band at 3628 cm(-1), while 1e lacks a nu(OH) absorption. The nu(OH) absorption in 1a,b is attributed to surface water, as use of D(2)O shifts the nu(OH) absorption to 2677 cm(-1), and that 1a-e are isostructural. Also, fcc Prussian blue-structured Cs(2)Mn[Mn(CN)(6)] (3) has been structurally [Fm3m: a = 10.6061(1) A] and magnetically characterized. The magnetic ordering temperature, T(c), increases as K(+) (41 K) > Rb(+) (34.6 K) > Cs(+) (21 K) for A(2)Mn[Mn(CN)(6)] in accord with the increasing deviation for linearity of the Mn-N-C linkages [148.8 (K(+)) > 153.3 (Rb(+)) > 180 degrees (Cs(+))], decreasing Mn(II)...Mn(II) separations [5.09 (K(+)) < 5.19 (Rb(+)) < 5.30 A (Cs(+))], 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)...Mn(II) separations, and perhaps enhanced overlap. In addition, the temperature dependent magnetic behavior of K(4)[Mn(II)(CN)(6)].3H(2)O is reported.
在水相和非水相介质中，Mn(II)和 KCN 的反应导致了三维（3-D）普鲁士蓝类似物 K(2)Mn[Mn(CN)(6)]（1a-d、1e，分别）的分离。使用 RbCN 形成 Rb(2)Mn[Mn(CN)(6)]（2）。1 和 2 是同构的{单斜，P2(1)/n: 1 [a = 10.1786(1) A, b = 7.4124(1) A, c = 6.9758(1) A, beta = 90.206(1)(o)]; 2 [a = 10.4101(1) A, b = 7.4492(1) A, c = 7.2132(1) A, beta = 90.072(1)(o)]}，与之前报道的 K(2)Mn[Mn(CN)(6)]的面心立方（fcc）结构的小单斜扭曲。值得注意的是，1 和 2 的平均 Mn-N-C 角分别为 148.8 度和 153.3 度，明显低于线性。这归因于高自旋 Mn(II)的离子性质，它可以容纳一个更小的 M-CN-M'角度并最小化空隙空间。化合物 1a、b 在 3628 cm(-1)处有一个尖锐、强的 nu(OH)带，而 1e 则没有 nu(OH)吸收。1a、b 中的 nu(OH)吸收归因于表面水，因为使用 D(2)O 将 nu(OH)吸收移至 2677 cm(-1)，并且 1a-e 是同构的。此外，还对具有 fcc 普鲁士蓝结构的 Cs(2)Mn[Mn(CN)(6)]（3）进行了结构[Fm3m: a = 10.6061(1) A]和磁性表征。磁性有序温度 T(c)随着 A(2)Mn[Mn(CN)(6)]中 K(+)（41 K）>Rb(+)（34.6 K）>Cs(+)（21 K）的增加而增加，这与 Mn-N-C 键的线性偏差增加一致[148.8 (K(+)) > 153.3 (Rb(+)) > 180 度 (Cs(+))]，Mn(II)...Mn(II)分离减小[5.09 (K(+)) < 5.19 (Rb(+)) < 5.30 A (Cs(+))]，以及阳离子尺寸减小（静电相互作用增加）。因此，弯曲的氰化物桥通过缩短 Mn(II)...Mn(II)分离来增加通过较短 Mn(II)...Mn(II)分离的耦合，从而在超交换机制中发挥关键作用，并且可能增强了重叠。此外，还报道了 K(4)[Mn(II)(CN)(6)].3H(2)O 的温度相关磁行为。
