J. J. Xu

Four new lanthanide-nitronyl nitroxide (Ln(III) = Pr(III), Sm(III), Eu(III), Tm(III)) complexes and a Tb(III) complex exhibiting single-molecule magnet behavior.

Five new complexes based on rare-earth-radical [Ln(hfac)(3)(NIT-5-Br-3py)](2) (Ln = Pr (1), Sm (2), Eu (3), Tb (4), Tm (5); hfac = hexafluoroacetylacetonate; NIT-5-Br-3py = 2-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)-5-bromo-3-pyridine) have been synthesized and characterized by X-ray crystal diffraction. The single-crystal structures show that these complexes have similar structures, in which a NIT-5-Br-3py molecule acts as a bridging ligand linking two Ln(III) ions through the oxygen atom of the N-O group and nitrogen atom from the pyridine ring to form a four-spin system. Both static and dynamic magnetic properties were measured for complex 4, which exhibits single-molecule magnetism behavior.

Structure Determination and Relative Properties of Novel Chiral Orthoborate KMgBO3

A novel chiral orthoborate, KMgBO(3), has been successfully synthesized via a standard solid-state reaction, and the crystal structure has been determined from powder X-ray diffraction data. It crystallizes in the cubic chiral space group P2(1)3. Isolated [BO(3)](3-) anionic groups, which are the fundamental building units, are distributed around the 111 crystallographic direction in an axial C(3) symmetry, and the configuration of O(3) planes is helical, similar to the aplanar ClO(3) groups in NaClO(3), which indicates an optical activity in it and is validated by the circular dichroism spectrum. The chiral feature of the borate is unique, and because of the noncentrosymmetric structure, the compound exhibits nonlinear optical properties, which are validated by second harmonic generation powder measurement. It has a wide transparency, including the vacuum ultraviolet region. The relations between the structures of KMgBO(3) and NaClO(3) and structural conversion form KMgBO(3) to NaMgBO(3) are also discussed. The ionic radii, interatomic distance, and the rigid tilting of BO(3) groups are considered to be the main factors in the crystallization of different structures.

Synthesis, crystal structure and magnetic properties of a dinuclear manganese(III) tetradentate Schiff-base complex

A dinuclear manganese(III) tetradentate Schiff-base complex, [Mn2(salophen)2(4,4′-bipy)3](BPh4)2 (1) (salophen = N,N′-o-phenylene-bis(salicylideneaminato)), has been synthesized and structurally characterized. Compound 1 crystallized in the triclinic, P 1 space group, a = 13.431(4), b = 13.791(4), c = 13.886(4) Å, α = 73.599(5)°, β = 80.410(6)°, γ = 71.241(5)°, V = 2328.3(12) Å3. Complex 1 contains two Mn(salophen) moieties bridged by 4,4′-bipy to form a dinuclear unit, with two terminal 4,4′-bipy ligands. Variable temperature magnetic susceptibility (2–300 K) shows very weak ferromagnetic interactions between the Mn(III) ions.

Synthesis and crystal structure of a three-dimensional 3d-4f heterometallic supramolecular complex {Eu(DMF)4(H2O)2Cr(CN)6·;H2O} n

A lanthanide-transition heterometallic supramolecular complex {Eu(DMF)4(H2O)2Cr(CN)6·H2O} n (1) has been synthesized based on the reaction of K3[Cr(CN)6], N,N-dimethylformamide (DMF) and Eu(NO3)3·6H2O. 1 crystallizes in the monoclinic space group P2(1)/c with a=13.130(6)Å, b=12.923(7)Å, c=19.184(9)Å and Z=4. In 1 each Eu(III) is eight-coordinate with six oxygen atoms from four DMF molecules and two H2O molecules and two nitrogen atoms from two cis-bridging CN ligands to form a distorted dodecahedron. 1 has a three-dimensional network created by the incorporation of coordinative linkage, three inter-molecular and an intrachain hydrogen bond.

Structural study of nonlinear optical borates K 1− x Na x Sr 4 (BO 3 ) 3 ( x ≤0.5)

X-ray powder diffraction was used for the structural study of nonlinear optical borates K 1− x Na x Sr 4 (BO 3 ) 3 ( x ≤0.5). Results show that up to 50% K + can be substituted by Na + in orthorhombic K 1− x Na x Sr 4 (BO 3 ) 3 . Isolated BO 3 triangles in the Na-substituted compound constrict to adjust to a local distribution of alkali-metal atoms, which explains the large range of structural homogeneity. An expansion of the c axis in a unit cell with increasing Na substitution was found probably caused by the tilted BO 3 triangles and asymmetric distortion of (K/Na)O 8 polyhedra. As the ratio of ionic radii of alkaline-earth and alkali-metal cations decreases and the electronegative difference between alkaline-earth and alkali-metal cations increases, the crystal system of MM ′ 4 (BO 3 ) 3 borates changes from cubic to orthorhombic and then to monoclinic.