Ca11N6(CN2)2 und Ca4N2(CN2): Die wahre Natur eines „ungewöhnlichen binären Nitrids” wird enthüllt

Cr2(NCN)3, a ferromagnetic carbodiimide with an unusual two-step magnetic transition

Crystallographic and magnetic characterization of a ferromagnetic transition-metal carbodiimide with an unusual two-step magnetic phase transition.

FeNCN and Fe(NCNH)2: synthesis, structure, and magnetic properties of a nitrogen-based pseudo-oxide and -hydroxide of divalent iron

Iron man challenge: Iron carbodiimide, FeNCN, and its precursor iron (bis)monohydrocyanamide, Fe(NCNH)(2), have been synthesized and physically characterized. Both FeNCN and Fe(NCNH)(2) exhibit nitrogen-mediated antiferromagnetic superexchange interactions with reduced magnetic moments very similar, but not identical, to the correlated 3d oxides.

Precursor approach to lanthanide dioxo monocarbodiimides Ln2O2CN2 (Ln=Y, Ho, Er, Yb) by insertion of CO2 into organometallic Ln-N compounds

We present two organometallic precursor approaches leading to the hitherto-unknown dioxo monocarbodiimides (Ln(2)O(2)CN(2)) of the late lanthanides Ho, Er, and Yb as well as yttrium. One involves insertion of CO(2), and the other one is a straightforward route using a molecular single-source precursor. To this end the reactivity of the activated amido lanthanide compound [(Cp(2)ErNH(2))(2)] towards carbon dioxide absorption under supercritical conditions was studied. Selective insertion of CO(2) into the amido complex yielded the single-source precursor [Er(2)(O(2)CN(2)H(4))Cp(4)], which was characterized by vibrational spectroscopy and thermal and elemental analyses. Ammonolysis of this amorphous compound at 700 degrees C affords Er(2)O(2)CN(2). To gain deeper insight into the structural characteristics of the amorphous precursor, a similar molecular carbamato complex was synthesized and fully characterized. X-ray structure analysis of the dimeric complex [Cp(4)Ho(2){mu-eta(1):eta(2)-OC(OtBu)NH}] shows an unusual bonding mode of the tert-butylcarbamate ligand, which acts as both a bridging and side-on chelating group. Ammonolysis of this compound also yielded dioxo monocarbodiimides, and therefore the crystalline carbamato complex turned out to be an alternative precursor for the straightforward synthesis of Ln(2)O(2)CN(2). Analogously, the dioxo monocarbodiimides of Y, Ho, Er, and Yb were synthesized by this route. The crystal structures were determined from X-ray powder diffraction data and refined by the Rietveld method (Ln=Ho, Er). Further spectroscopic characterization and elemental analysis evidenced the existence of phase-pure products. The dioxo monocarbodiimides of holmium and erbium crystallize in the trigonal space group P[over]3m1. According to X-ray powder diffraction, they adopt the Ln(2)O(2)CN(2) (Ln=Ce-Gd) structure type.

Experimental and quantum-chemical studies on the thermochemical stabilities of mercury carbodiimide and mercury cyanamide

Calorimetric dissolution measurements of the solid compounds mercury carbodiimide HgNCN(I) and mercury cyanamide HgNCN(II) in aqueous HCl that targeted at their thermochemical stabilities show the cyanamide species HgNCN(II) to be the more stable phase in terms of both enthalpy and Gibbs energy with an enthalpy difference of 2-3 kJ mol-1. While the stability ranking of HgNCN(I) and HgNCN(II) thus perfectly matches Pearson's HSAB concept, quantum-chemical stability predictions using common parametrizations of density functional theory appear to be fundamentally flawed. An analysis of the error is attempted on the basis of correlated wave functions for related molecules.