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About the air- and water-stable copper(I) dicyanamide: synthesis, crystal structure, vibrational spectra and DSC/TG analysis of Cu[N(CN)2]

Reckeweg, Olaf, Dinnebier, Robert E., Schulz, Armin, Blaschkowski, Björn, Schneck, Christof, Schleid, Thomas
Zeitschrift für Naturforschung B 2017 v.72 no.2 pp. 159-165
copper, crystal structure, cyanides, differential scanning calorimetry, ions, mixing, silver, sodium, thermogravimetry
Light-yellow microcrystalline samples of Cu[dca] ([dca]⁻≡[N(CN)₂]⁻≡dicyanamide anion) were obtained by blending an in-situ generated aqueous Cu⁺ brine with stoichiometric amounts of Na[dca] dissolved in water. The crystal structure of Cu[dca] was solved and refined from powder X-ray diffraction (PXRD) data. Cu[dca] crystallizes in the orthorhombic space group Cmcm (no. 63) with the lattice parameters of a=356.28(3), b=611.10(9) and c=1525.87(10) pm. The crystal structure contains undulated chains of alternating Cu⁺ and boomerang-shaped [N≡C–N–C≡N]⁻ ions with C₂ᵥ symmetry running along [100]. It is closely related to that of Ag[dca] crystallizing in space group Pnma (no. 62). The vibrational spectra for Cu[dca] and Cu[dca]₂ were recorded exhibiting modes typical for the dicyanamide anion. Comparative DSC/TG measurements were performed for both copper dicyanamides and the cyanide Cu[CN].