Synthesis and Crystal Structure of Ammine Copper(I) Cyanamide, Cu₄(NCN)₂NH₃

Abstract

Ammine copper(I) cyanamide, Cu4(NCN)2NH3, was obtained as a white powder from the reaction between CuCl and H2NCN in concentrated ammonia solution. X‐ray and neutron diffraction experiments yield the hexagonal system with space group P63mc (no. 186) and a = 5.7661(1) Å, c = 10.7817(3) Å, and Z = 2. The structure is characterized by layers of monovalent copper ions with an average Cu–Cu distance of 2.89Å, and the layers are connected through two crystallographically independent NCN2− units. While one CuI is linearly bonded to an NCN2− unit and an additional NH3 molecule, the other CuI is also linearly coordinated but by two NCN2− groups; the Cu–N bonds lie between 1.86–1.98Å. The C–N bond lengths and angles evidence both NCN2− groups as essentially linear cyanamides.

A Ferromagnetic Carbodiimide: Cr2(NCN)3

“…[16] The NCN 2À ion, which is practically linear (N-C-N 178.0(7)8), experiences a distorted tetrahedral coordination by the Cr ions, and it almost coincides with the c axis. Thus, this unit adopts the symmetrical carbodiimide shape with CÀN 1.208 (4) , and this can also be verified by the IR spectrum of Cr 2 (NCN) 3 , which shows asymmetric stretching vibrations of the NCN 2À unit at n as = 2005 and 2094 cm À1 together with the deformation vibrations d at 635 and 696 cm À1 . The magnetic susceptibility data of Cr 2 (NCN) 3 were determined at applied fields B 0 between 0.01 and 0.5 T in the temperature range between 2 and 400 K. We note that the experimentally derived paramagnetic moment, on the basis of this C value, equals 3.6 m B which is very close to an ideal octahedral 3d 3 high-spin system (Cr .…”

“…The best fit arrived at B 4 0 = À16050 cm À1 , l mf = 8.589 10 7 mol m À3 , and SQ = 1.3 %, where B k q refers to the Wybourne notations [20] of the ligandfield parameters and SQ = S[(c obs Àc cal )/(c obs )] 2 quantifies the fit quality. The size of l mf corresponding to q = 178 K for a ligand-field ground term 4 A 2 suggests very strong exchange interactions, and the positive signs of both q and l mf indicate dominantly ferromagnetic interactions. Indeed, a magnetochemical CONDON analysis provides a satisfactory fit only if ferromagnetic interactions are considered.…”

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Extended pseudochalcogenides such as the solid-state carbodiimides (incorporating complex À N = C = N À units with D 1h symmetry) or cyanamides (with a less symmetrical N C À N 2À unit) have been extensively investigated, and a large number including alkali [1] and alkaline-earth metals, [2] main-group elements, [3] d 10 transition metals, [4] and also rare-earth metals [5] have been reported. The synthesis of the complete set of MNCN (M = Mn-Cu) phases with only partially filled 3d orbitals, however, looked far more difficult, because firstprinciples calculations [6] had predicted them to be unstable in terms of formation enthalpy DH f and Gibbs formation energy DG f , with the instability continuously rising from MnNCN to CuNCN, thereby mirroring the gradual filling of antibonding levels from 3d 5 to 3d 9 .

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Determination of the magnetic structure of manganese carbodiimide with diffraction experiments using polarized neutrons

“…A good number of inorganic carbodiimides/cyanamides has been synthesized containing alkali [1][2][3][4][5] and alkaline-earth metals, [6][7][8][9] main-group elements, [10][11][12][13][14] d 10 transition metals, [15][16][17][18][19][20][21] and also rare-earth metals. [22][23][24][25] In 2005, the existence of quasibinary compounds containing non-d 10 magnetically active metals was first predicted using densityfunctional theory, indicating that all MNCN ͑M = Mn, Fe, Co, Ni, and Cu͒ phases should be unstable with respect to both formation enthalpy ⌬H f and Gibbs formation energy ⌬G f .…”

Synthesis, structure and magnetic property of a cyanamido bridged trinuclear copper complex

“…Among them, pseudohalide anions [4] represent one of the most intensively studied groups and large amounts of metal complexes with different architectures and magnetic properties have been prepared with azido or dicyanamido anions as bridging ligand [5,6]. As the isoelectronic compound of the azido anion, cyanamido anion (NCN 2À ) has also been used in the assembly with transition metal ions, but it is far less studied compared to its analogues with azido ligand [7][8][9][10][11][12][13]. In the literatures, the structures and magnetic properties of some complexes with bridging hydrogencyanamido anion (NCNH À ) have been reported [14][15][16][17][18].…”