The electron gas thus tries to approach the various cations, while the cations themselves repel each other.Ĭonsequently, there is an state of equilibrium in which both forces compensate each other. On the other hand, there are repulsive forces between the cations themselves due to their identical charges. On the one hand, there are attractive forces between the positively charged ions and the negatively charged electron gas. CRYSTAL LATTICE STRUCTURE FREEDue to the released electrons, a kind of “gaseous” state of the free electrons is formed around the positive ions. In this way, positively charged metal ions remain (cations). The metal atoms release all their outer electrons and thus reach the noble gas configuration. The structure of metals has already been explained shortly in the chapter on metal bonding. Due to this special position of metals in mechanical engineering, their atomic structure is discussed in more detail below. In addition, metals have a very good thermal conductivity and electrical conductivity, which gives these materials a wide range of applications. Compared to other materials, they can withstand relatively high loads, but still have sufficient plasticity (ductility) not to break immediately under stress. Alternating current magnetic susceptibility measurements performed on complexes 2-4 revealed that 3 and 4 displayed frequency dependent Chi” signals (Hac = 3.5 Oe and Hdc = 0 Oe) which is a characteristic signature of a single-molecule magnet behaviour.Metals play an important role in mechanical engineering. The magnetic data of 1 were fitted using the HDVV Hamiltonian revealing the following parameters J = +0.46 cm-1, g = 2.245, D = +4.91 cm-1. For complex 1 a long range intramolecular ferromagnetic interaction is witnessed between the Ni(II) ions (Ni.Ni = 6.873(9) Å) via a closed shell La(III) ion. Direct current magnetic susceptibility measurements for complexes 1-4 reveal that the Ni(II) ions are coupled ferromagnetically with the Tb(III) (3) and Dy(III) (4) ions, and antiferromagnetically with the Pr(III) ion (2). Analysis of 4 reveals the metal ions are arranged such that two Ni-Dy subunits are bridged by two carbonate ligands via the Dy sites. Structural analysis for 1-3 reveals that the lanthanide ion is sandwiched between two Ni(II) ions and the Ni…Ln.Ni metallic core displays a linear arrangement, with an average angle Ni…Ln.Ni bond angle of 179.7 degree. The molecular structures of these complexes were determined via single crystal X-ray diffraction, revealing molecular structures of formulae (NO3) where Ln = La (1), Pr (2) and Tb (3) and (4). The reaction of hydrated nickel(II) salts (chloride or nitrate) and various hydrated lanthanide nitrate salts with the Schiff base ligand 2-methoxy-6- phenol (HL) in methanol resulted in the isolation of three isostructural linear heterometallic trinuclear complexes and a heterometallic tetranuclear complex. The catechol oxidation abilities are comparable from two complexes of different nuclearity and structure. Both the complexes show effective solvent-dependent catechol oxidation toward 3,5-di-tert-butylcatechol in air. Complex 1 exhibited field-induced slow magnetic relaxation at 2 K due to the axial anisotropy of Mn(III) centers. The magnetic characterization of 1 and 2 revealed the properties dominated by intramolecular anti-ferromagnetic exchange interactions, and this was confirmed using density functional theory calculations. Two novel Cd-based coordination polymers Cd(H2BCP)2(phen)21 and (2-). The magnetic entropy change was found to be 34.5 J kg−1K−1, making 1 a plausible candidate in magnetic cooling applications. The large number of isotropic Gd(III) ions comprising 1 makes it a candidate for magnetocaloric applications, thus the magnetocaloric properties of this molecular cage were investigated indirectly through isothermal magnetisation curves. 2 K, the magnetic measurements for compound 1 suggests antiferromagnetic interactions between the Gd(III) metal ion centers at low temperatures. The magnetic behavior of 1 and 2 was investigated between ambient temperature and ca. The molecular structure of compounds 1 and 2 reveal two highly unsymmetrical complexes comprising ten lanthanide metal centers, where the lanthanide metal ion centers in the cages are linked through pivalate units and further interconnected by CPO3 tetrahedra to build the crystal structure. Both compounds have been characterized with elemental analysis, single-crystal X-ray diffraction methods, and magnetic measurements. Two isostructural lanthanide amino-phosphonate complexes (Ln = Gd(III), 1 and Tb(III), 2) have been obtained through reflux reactions of lanthanide pivalates with, a functionalized phosphonate, (1-amino-1-cyclohexyl)phosphonic acid and diethylamine (Et2NH) in acetonitrile (MeCN) at 90 ☌.
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