New heterometallic polynuclear complexes

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A ring cycle: studies of heterometallic wheels

The synthesis of a series of heterometallic rings and chains is reported. The family is based on the octanuclear cages of general formula [H2NR2][M7M’F8(O2Cr’)16], where M is a trivalent metal (Cr, Fe, V, Al, Ga or In), M’ is a divalent metal (Mn, Fe, Co, Ni, Mg, Zn, Cd), R is a linear alkyl chain and O2CR’ is one of around twenty carboxylates. Other members of the family with nanometallic and decametallic cores are described, and some new physics is outlined, including initial investigations of the proposed application of {Cr7Ni} rings as Qubits in quantum information processing

New high-spin clusters featuring transition metals

Three possible routes to polynuclear transition metal complexes are discussed. The first route, oligomerization induced by desolvation of small cages, is exemplified by synthesis of a dodecanuclear cobalt cage, and by reactions which give octa– and dodecanuclear chromium cages. The second route involves linking cages through organic spacers, and is illustrated by use of phthalate to link together cobalt and nickel cages. For the nickel case a complex consisting of four cubanes and a sodium octahedron is found. The third route involves the use of water to introduce hydroxide bridges into cages. One method of introducing water is to use hydrated metal salts; the transformation of a Cu6Na cage into a Cu12La8 illustrates this approach. Alternatively, adventitious water within solvents can be used as a source, and this approach has led to a Co24 cage. The structures and magnetic properties of these various cages are discussed

Quantum Oscillations of the Total Spin in Heterometallic AF Rings - Evidence from Neutron Spectroscopy

Using inelastic neutron scattering and applied fields up to 11.4 T, we have studied the spin dynamics of the Cr7Ni antiferromagnetic ring in the energy window 0.05 - 1.6 meV. We demonstrate that the external magnetic field induces an avoided crossing (anticrossing) between energy levels with different total-spin quantum numbers. This corresponds to quantum oscillations of the total spin of each molecule. The inelastic character of the observed excitation and the field dependence of its linewidth indicate that molecular spins oscillate coherently for a significant number of cycles. Precise signatures of the anticrossing are also found at higher energy, where measured and calculated spectra match very well.JRC.E.6-Actinides researc

Quantum Oscillations of the Total Spin in a Heterometallic Antiferromagnetic Ring: Evidence from Neutron Spectroscopy

Using inelastic neutron scattering and applied fields up to 11.4 T, we have studied the spin dynamics of the Cr7Ni antiferromagnetic ring in the energy window 0.05–1.6 meV. We demonstrate that the external magnetic field induces an avoided crossing (anticrossing) between energy levels with different total-spin quantum numbers. This corresponds to quantum oscillations of the total spin of each molecule. The inelastic character of the observed excitation and the field dependence of its linewidth indicate that molecular spins oscillate coherently for a significant number of cycles. Precise signatures of the anticrossing are also found at higher energy, where measured and calculated spectra match very well