Synthesis, Crystal Structure, Thermal, Spectroscopic and Magnetic Properties of a 2D Grid‐like Copper(II) μ‐1,1 Isocyanato Coordination Polymer with Pyrazine Bridges

Abstract

Reaction of copper(II) cyanate with pyrazine leads to the formation of [Cu(NCO)2(pyrazine)]n (1), in which the Cu2+ cations are coordinated by two nitrogen atoms of the pyrazine ligands, as well as by four nitrogen atoms of the cyanate anions within a slightly distorted octahedral coordination. In the crystal structure the Cu2+ cations are connected by the pyrazine ligands into chains which are further linked by the cyanate anions through asymmetric μ‐1,1‐NCO coordination into layers. On heating compound 1 transforms quantitatively to copper(II) cyanate which decompose to elemental copper on further heating. No ligand deficent intermediates are observed. Magnetic measurements reval an antiferromagnetic ordering at lower temperatures mediated by the π‐system of the aromatic pyrazine ligand as well as net ferromagnetic interactions mediated by the μ‐1,1‐NCO bridging cyanato anions. A search in the Cambridge Crystal Structure Database shows that the terminal coordination mode in cyanato complexes as well as their azido and thiocyanato analogs is obviously energetically favored. In addition, a comparison of their symmetric and asymmetric end‐on (μ‐1,1) as well as end‐to‐end (μ‐1,3) bridging modes reveal interesting correlations.

National Medal of Science: A. J. Bard, J. B. Goodenough und M. F. Hawthorne / National Medal of Technology and Innovation: F. H. Arnold und R. S. Langer / Alexander von Humboldt‐Professur: M. W. Ribbe / ICS‐Exzellenzpreis: A. Gedanken und I. Marek / ICS‐Goldmedaille: R. D. Levine / Infosys‐Preis: A. Ajayaghosh

“…The central Ni 2+ cation (Ni1) is coordinated by four μ 2 ‐ N 1 , N 2 bridging pdz ligands and two thiocyanato anions in trans positions. Both thiocyanato anions exhibit the μ 2 ‐ N (end‐on) bridging mode, which is very rare for thiocyanato anions 25. The peripheral Ni 2+ cations (Ni2 and Ni2a) are μ 2 ‐ N (by one thiocyanato anion) and μ 2 ‐ N 1 , N 2 (by two pdz ligands) bridged with Ni1.…”

Synthesis, crystal structures and antimicrobial activity of azido and isocyanato Zn(II) complexes with the condensation product of 2-quinolinecarboxaldehyde and Girard’s T reagent

“…Pseudohalides (azide and cyanate) are versatile ligands which can be coordinated as monodentate species [1][2][3] or as bridges between metal centers [4][5][6][7]. The homoatomic azido ligand exhibits many bridging coordination modes: single and double μ 1,3 -N 3 (end-to-end, EE) and μ 1,1 -N 3 (end-on, EO), μ 1,1,3 -N 3 , μ 1,1,1 -N 3 , μ 1,1,1,1 -N 3 , μ 1,1,2,2 -N 3 , and μ 1,1,1,3,3,3 -N 3 [8].…”

New nickel(ii) thiocyanato coordination compounds: synthetic aspects, polymorphism, thermal reactivity and magnetic properties

“…In this approach precursor compounds based on octahedrally coordinated transition metal cations, terminal bonded small-sized anionic ligands and additional co-ligands are heated, which leads to a stepwise removal of the co-ligands and irreversibly to the formation of new intermediates that can be isolated very pure and in quantitative yields. [13][14][15][16][17][18][19][20][21][22][23][24] The dimensionality of the coordination networks of the intermediates can simply be predetermined by the coordination properties of the co-ligands. If these ligands are bidentate, the precursor consists of a 2D coordination network in which the metal cations are octahedrally coordinated by two terminal anionic ligands and four bridging neutral co-ligands (Fig.…”