π–π Interactions and magnetic properties in a series of hybrid inorganic–organic crystals

The crystal structure of poly[bis(N,N-dimethylformamide-κ1 O)-tetrakis(μ2-cyanido-κ2 C:N)dinickel(II)], C10H14N6O2Ni2

C10H14N6O2Ni2, monoclinic, I2/m (no. 12), a = 6.7377(1) Å, b = 7.3500(1) Å, c = 14.8647(2) Å, β = 96.051(1)°, V = 732.030(18) Å3, Z = 8, R gt(F) = 0.0314, wR ref(F 2) = 0.0996, T = 150.01(10) K.

From 3D to 2D Transition Metal Nitroprussides by Selective Rupture of Axial Bonds

1-methyl-2-pyrrolidone (1m2p) is a solvent with proven abilities for 2D-solid exfoliation due to its extremely high surface tension. In principle, such a feature could be used also to induce the selective breaking of certain bonds in solids to obtain new materials. Such a hypothesis is demonstrated in this study for transition metal nitroprussides, where 2D solids are obtained from 3D frameworks by selective rupture of axial bonds. This contribution discusses the mechanism involved in such molecular manufacture. The crystal structure for the formed 2D solids was solved and refined from XRD powder patterns recorded using synchrotron radiation. Mössbauer, IR and Raman spectra provided fine details on the electronic structure of the resulting new series of layered materials. The experimental information was complemented with calculations for the molecule configuration in its non-activated and activated forms. In the obtained 2D solids, neighboring layers of about 1 nm of thickness remain separated by activated 1m2p molecules. The interaction between neighboring layers is of a physical nature, without the presence of a chemical bond between them, as corresponds to a 2D material.

Relevant electronic interactions related to the coordination chemistry of tetracyanometallates. An XPS study

In the K₂[M(CN)₄]·xH₂O (M = Ni, Pd, Pt) series, the CN ligand is found to donate electron density to the K ion, which is detected as a decrease in the K 2p BE. The charge donated is proportional to that removed from the inner metal (M) via π-back bonding.

New coordination polymers based on 2-methylimidazole and transition metal nitroprusside containing building blocks: synthesis, structure and magnetic properties

In this study, we report the synthesis, structural and magnetic properties of coordination polymers based on transition metal nitroprussides and 2-methylimidazole as ligands.

Vibrational spectra, powder X-ray diffractions and physical properties of cyanide complexes with 1-ethylimidazole

The heteronuclear tetracyanonickelate(II) complexes of the type [M(etim)Ni(CN)4]n (hereafter, abbreviated as M-Ni-etim, M=Mn(II), Fe(II) or Co(II); etim=1-ethylimidazole, C5H8N2) were prepared in powder form and characterized by FT-IR and Raman spectroscopy, powder X-ray diffraction (PXRD), thermal (TG; DTG and DTA), and elemental analysis techniques. The structures of these complexes were elucidated using vibrational spectra and powder X-ray diffraction patterns with the peak assignment to provide a better understanding of the structures. It is shown that the spectra are consistent with a proposed crystal structure for these compounds derived from powder X-ray diffraction measurements. Vibrational spectra of the complexes were presented and discussed with respect to the internal modes of both the etim and the cyanide ligands. The C, H and N analyses were carried out for all the complexes. Thermal behaviors of these complexes were followed using TG, DTG and DTA curves in the temperature range 30-700 °C in the static air atmosphere. The FT-IR, Raman spectra, thermal and powder X-ray analyses revealed no significant differences between the single crystal and powder forms. Additionally, electrical and magnetic properties of the complexes were investigated. The FT-IR and Raman spectroscopy, PXRD, thermal and elemental analyses results propose that these complexes are similar in structure to the Hofmann-type complexes.

Dehydration Process of Hofmann-Type Layered Solids

In the present work the dehydration process of layered solids with formula unit M(H₂O)₂[Ni(CN)₄]·nH₂O, M = Ni, Co, Mn; n = 1, 2, 4 is studied using modulated thermogravimetry. The results show that water molecules need to overcome an energetic barrier (activation energy between 63 and 500 kJ/mol) in order to diffuse through the interlayer region. The related kinetic parameters show a dependence on the water partial pressure. On the other hand, X-ray diffraction results provide evidence that the dehydration process is accompanied by framework collapse, limiting the structural reversibility, except for heating below 80 °C where the ordered structure remains. Removal of water molecules from the interlayer region disrupts the long-range structural order of the solid.