Hydratisierte Cyanoelpasolithe: Bis(tetramethylammonium)diaquaIithium-hexacyanometallate(III) des Mangans, Eisens und Cobalts / Hydrated Cyanoelpasolites: Bis(tetramethylammonium)diaqualithium-hexacyanometallates(III) of Manganese, Iron and Cobalt

Abstract

<jats:p>The crystal structures of three isotypic hexacyanometallates(III) (NMe<jats:sub>4</jats:sub>)<jats:sub>2</jats:sub>LiM(CN)<jats:sub>6</jats:sub>·2H<jats:sub>2</jats:sub>O have been determined and refined in the monoclinic space group C2/c, Z = 4, to wR = 0.053 (M = Mn, 959 independent single crystal reflections), 0.041 (M =Fe, 2002 reflections) and 0.037 (M = Co, 1881 reflections). The stucture is elpasolite-related by its face-centered pseudocubic arrangement of M atoms within nearly undistorted M(CN)<jats:sub>6</jats:sub><jats:sup>3-</jats:sup> octahedra, six of which form strongly distorted octahedral N<jats:sub>6</jats:sub> cavities occupied by dihydrated lithium ions. The resulting average distances for the M(CN)<jats:sub>6</jats:sub><jats:sup>3-</jats:sup> octahedra are Mn-C = 201, Fe-C = 194.7, Co-C = 190.3, and C-N = 114 pm. The lithium coordination is distorted tetrahedral, consisting of LiO<jats:sub>2</jats:sub>N<jats:sub>2</jats:sub> units with distances of about Li-O = 194, Li -N = 209 pm (for M = Fe, Co). The remaining four N atoms of the N<jats:sub>6</jats:sub> cavity are bound by hydrogen bridges from the two aqua ligands, O-H···N = 283 and 295 pm. The relations to the hydrated elpasolite structure of (NMe<jats:sub>4</jats:sub>)<jats:sub>2</jats:sub>NaFe(CN)<jats:sub>6</jats:sub>·H<jats:sub>2</jats:sub>O are discussed.</jats:p>

Unprecedented N-E Bond Cleavage (E=Sn, Pb) by R4N+ Ions (R=nBu, nPr): Formation, Architecture, and Multinuclear Magnetic Resonance Spectroscopy of Novel Supramolecular [(R4N)(Me3E)2M(CN)6⋅H2O] Assemblies (M=Fe, Co)

“…The solid-state NMR spectra were recorded on a Varian VXR 300 spectrometer operating at frequencies of 75.4, 111.9, 30.4, and 71.1 MHz for 13 N, and 59 Co respectively. Preparation of 2 a ± 2 f (see Table 1):…”

“…Between d À 66 and À 73, there seem to be six resolved or partly resolved lines although five are expected (including those from O-Sn-N groups) from the structure as determined by X-ray diffraction. We believe this modest discrepancy probably arises either from quadrupolar effects from As is usually observed at ambient temperature, we assume rapid (on the NMR time scale) rotation of all Me 3 Sn groups about their trigonal axes, so that only eight 13 C resonances would be expected for the twenty-four crystallographically different (at least in the case of 2 a) Sn-bonded methyl carbon atoms. However, only five distinct 13 C resonances of Snbonded Me groups are detectable at room temperature, although deconvolution of the methyl carbon resonance range actually leads to eight individual lines at d 1.9, 1.6, 1.5, 1.4, 0.7 (two lines), 0.0 and À 0.2 (with an apparent intensity range over a factor of 2).…”

“…The corresponding O´´´N distances (Table 4) are considerably shorter than the shortest O´´´N contacts which have been observed, for example in 4 (312.2 pm [10] ) and in 5 (305.2 and 297.2 pm [11] ). The OÀH´´´N cyanide bridges with O´´´N distances ranging between 280 and 295 pm are, however, wellknown for numerous salt hydrates, for example the dihydrated cyanoelpasolites [(NMe 4 ) 2 LiM(CN) 6´2 H 2 O] (M Fe,Co [13] ). In addition, seven of the nine virtually terminal cyanide ligands of 2 a exhibit at least one notably short (i.e.`350 pm) N´´´C contact (Table 4) owing to potential CÀH´´´N hydrogen bridges with some of the satisfactorily ªacidicº amethylene groups of the nBu 4 N cations.…”

“…As 1 b and 1 d are known to display (relatively broad) resonances between d 132 and 135, the somewhat wider resonance range of 2 b seems to reflect the presence of both bridging and virtually terminal cyanide ligands. The strong crowding and overlapping of the (18 expected) cyanide 13 C lines is obviously due to the generally narrower 13 C-resonance range (than e.g. the 15 N cyanide range), and to the high nuclear quadrupole moment of the adjacent 59 Co nucleus.…”

“…the 15 N cyanide range), and to the high nuclear quadrupole moment of the adjacent 59 Co nucleus. Usually, iron cyanides display more resolvable 13 C patterns. [16] The 59…”