title: Single-ion magnet behaviour in mononuclear and two-dimensional dicyanamide-containing cobalt(ii) complexes.
abstract: Three cobalt(ii) complexes of formulae [Co(dca)2(bim)4] (), [Co(dca)2(bim)2]n () and [Co(dca)2(bmim)2]n () [dca = dicyanamide, bim = 1-benzylimidazole and bmim = 1-benzyl-2-methylimidazole] were prepared and structurally analyzed by single-crystal X-ray crystallography. Compound is a mononuclear species where the cobalt(ii) ion is six-coordinate with four bim molecules in the equatorial positions [Co-Nbim = 2.1546(15) and 2.1489(15) Å] and two trans-positioned dca ligands [Co-Ndca = 2.1575(18) Å] in the axial sites of a somewhat distorted octahedral surrounding. The structures of and consist of two-dimensional grids of cobalt(ii) ions where each metal atom is linked to the other four metal centres by single dca bridges exhibiting the μ1,5-dca coordination mode [Co-Ndca = 2.190(3)-2.220(3) () and 2.127(3)-2.153(3) Å ()]. Two trans-coordinated bim ()/bmim () molecules achieve the six-coordination around each cobalt(ii) ion [Co-Nbim = 2.128(3)-2.134(4) Å () and Co-Nbmim = 2.156(3)-2.163(39) Å ()]. The values of the cobalt-cobalt separation through the single dca bridges are 8.927(2) and 8.968(2) Å in and 8.7110(5) and 8.7158(5) Å in . Magnetic susceptibility measurements for in the temperature range of 2.0-300 K reveal that these compounds behave as magnetically isolated high-spin cobalt(ii) ions with a significant orbital contribution to the magnetic moment. Alternating current (ac) magnetic susceptibility measurements for show a frequency dependence of out-of-phase susceptibility under static applied fields in the range of 500-2500 G, a feature which is characteristic of the single-ion magnet behaviour (SIM) of the Co(ii) ion in them. The values of the energy barrier for the magnetic relaxation (Ea) are 5.45-7.74 (), 4.53-9.24 () and 11.48-15.44 cm(-1) (). They compare well with those previously reported for the analogous dca-bridged 2D compound [Co(dca)2(atz)2]n () (Ea = 5.1 cm(-1) under an applied static field of 1000 G), which was the subject of a previous report.
authors.affiliation: Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland. anna.switlicka@gmail.com.
authors.forename: Anna
authors.initials: A
authors.lastname: Switlicka-Olszewska
authors.affiliation: Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland. anna.switlicka@gmail.com.
authors.forename: Joanna
authors.initials: J
authors.lastname: Palion-Gazda
authors.affiliation: Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland. anna.switlicka@gmail.com.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Klemens
authors.affiliation: Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland. anna.switlicka@gmail.com.
authors.forename: Barbara
authors.initials: B
authors.lastname: Machura
authors.affiliation: Department of Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Facultat de Quimica de la Universitat de València, C/ Catedrático Jose Beltrán 2, 46980 Paterna, València, Spain. miguel.julve@uv.es.
authors.forename: Julia
authors.initials: J
authors.lastname: Vallejo
authors.affiliation: Department of Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Facultat de Quimica de la Universitat de València, C/ Catedrático Jose Beltrán 2, 46980 Paterna, València, Spain. miguel.julve@uv.es and Fundació General de la Universitat de València (FGUV), Universitat de València, 96480 Paterna, València, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Cano
authors.affiliation: Department of Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Facultat de Quimica de la Universitat de València, C/ Catedrático Jose Beltrán 2, 46980 Paterna, València, Spain. miguel.julve@uv.es.
authors.forename: Francesc
authors.initials: F
authors.lastname: Lloret
authors.affiliation: Department of Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Facultat de Quimica de la Universitat de València, C/ Catedrático Jose Beltrán 2, 46980 Paterna, València, Spain. miguel.julve@uv.es.
authors.forename: Miguel
authors.initials: M
authors.lastname: Julve