Topologic ferrimagnetism in cobalt(II)-azido chains.

New monodimensional Co(II)/azido systems with unusual topological ferrimagnetic response have been characterised.

A two-dimensional azido-based topologic ferrimagnet.

The reported Mn(II)-azide system is the first example of a two-dimensional homometallic ferrimagnet, in which the magnetic properties are due exclusively to topological reasons related with the coordination mode of the bridging ligands; it is also the first case in which a system of this kind exhibits long range order comparable to the classical heterospin ferrimagnets.

[M(N3)2(L)]n: building 3-D MII-azido networks with new topologies.

Novel 3D topologies combining diazine and azido bridges between MnII magnetic centres have been obtained and characterised by low-temperature magnetic measurements.

A New Family of High-Dimensional Molecular Magnets Built from the Manganese-Azido System. Syntheses, Structures, and Magnetic Characterization of Two New Ferro-Antiferromagnetic Two-Dimensional Complexes.

Two new compounds in the series of general formula [Mn(L)(2)(N(3))(2)](n)() in which L = 4-cyanopyridine (1) or 3-acetylpyridine (2) have been obtained and structurally and magnetically characterized. Both compounds crystallize in the monoclinic system, space group P2(1)/a, formula [C(12)H(8)MnN(10)] with a = 13.286(4) Å, b = 8.340(3) Å, c = 13.579(4) Å, beta = 90.55(2) degrees, and Z = 4 for compound 1 and space group P2(1)/c, formula [C(14)H(14)MnN(8)O(2)] with a = 11.843(4) Å, b = 9.550(3) Å, c = 14.998(5) Å, beta = 105.99(3) degrees, and Z = 4 for compound 2. The two compounds show a similar arrangement of alternating end-to-end and end-on azido bridges between the manganese atoms, giving magnetically alternated ferro-antiferromagnetic two-dimensional compounds. The pyridyl ligands coordinated to the axial sites stick out above and below the 2-D sheets, and intersheet pi-pi interactions are formed between the pyridyl ligands, playing a role in the structural differences. The low-temperature magnetic properties of 1 and 2, together with those of the previously reported compounds with L = pyridine (3), 4-acetylpyridine (4), and ethyl isonicotinate (5), are reported. Magnetic ordering and spontaneous magnetization is achieved at T(C) = 18, 16, 40, 28, and 16 K for 1-5, respectively.

Structure and Magnetic Behavior of a New 1-D Compound with Simultaneous End-On Azido and Carboxylato Bridges. Unexpected Strong Ferromagnetic Coupling for a Cu-N-Cu Bond Angle of 111.9 degrees as a Consequence of Ligand HOMOs Countercomplementarity.

The X-ray structure of the &mgr;-carboxylate-&mgr;(1,1)-azido-bridged compound {[Cu(Hpht)(N(3))].H(2)O}(n)() has been determined (Hpht = hydrogen phthalate). Crystal data: formula C(8)H(7)CuN(3)O(5), monoclinic, P2(1)/m (No. 11), a = 7.383(3) Å, b = 6.568(4) Å, c = 10.659(4) Å, beta = 93.38(3) degrees, Z = 2. The compound is found to be a system formed by chains of copper atoms bridged simultaneously by syn-syn carboxylato and end-on azido bridges. The copper chains are linked by a second carboxylato bridge, giving a 2-D compound. Magnetic measurements indicate strong ferromagnetic coupling, which affords a good example of unexpected magnetic properties due to the countercomplementarity of the superexchange pathways of the two ligands.

Synthesis and Structural Characterization of [Mn(ethyl isonicotinate)(2)(N(3))(2)](n)(), a Two-Dimensional Alternating Ferromagnetic-Antiferromagnetic Compound. Magnetostructural Correlations for the End-to-End Pseudohalide-Manganese System.

Three compounds with formula [Mn(L)(2)(N(3))(2)](n)(), in which L is 4-acpy = 4-acetylpyridine (1), Etinc = ethyl isonicotinate (2), and py = pyridine (3), have been studied from the magnetic point of view. The new compound [Mn(L)(2)(N(3))(2)](n)() (2) crystallizes in the monoclinic system, space group P2(1)/a (No. 14), formula [C(16)H(18)MnN(8)O(4)], with a = 15.176(5) Å, b = 9.060(3) Å, c = 15.760(6) Å, beta = 111.62(3) degrees, and Z = 4. Compounds 1 and 2 are two-dimensional systems, whereas 3 is a 3-D compound. Compound 2 shows ferromagnetic Mn(2)(N(3))(2) dimeric entities linked antiferromagnetically to the four neighboring dimeric entities by four end-to-end azido bridges, leading to an alternate ferromagnetic-antiferromagnetic two-dimensional compound. MO calculations have been performed to study the superexchange pathway for the manganese 1,3-azido system.