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1.
Chem Commun (Camb) ; (20): 2126-7, 2001 Oct 21.
Article in English | MEDLINE | ID: mdl-12240195

ABSTRACT

The mixed valence cluster anion of the compound (NH4)32[MoVI110MoV28O416H6(H2O)58(CH3CO2)6].xH2O 1 (x approximately 250), synthesized under one-pot conditions, contains well-defined different types of defects--missing groups compared to the complete parent (Mo154) type cluster with full D7d symmetry--and acetate ligand coordination; this proves that the giant-wheel type anion can be considered as an object with a variety of nanoscale structural features ("nanostructured landscape") allowing reactions at a variety of well defined centers.

3.
Phys Rev Lett ; 84(15): 3454-7, 2000 Apr 10.
Article in English | MEDLINE | ID: mdl-11019113

ABSTRACT

Time resolved magnetization measurements have been performed on a spin 1/2 molecular complex, so-called V15. Despite the absence of a barrier, magnetic hysteresis is observed over a time scale of several seconds. A detailed analysis in terms of a dissipative two-level model is given, in which fluctuations and splittings are of the same energy. Spin-phonon coupling leads to long relaxation times and to a particular "butterfly" hysteresis loop.

8.
Angew Chem Int Ed Engl ; 38(21): 3238-3241, 1999 Nov 02.
Article in English | MEDLINE | ID: mdl-10556914

ABSTRACT

Pythagorean harmony can be found in the spherical polyoxometalate clusters described here (see illustration for an example of a structure), since there are interesting relationships between the so-called magic numbers (12, 32, 42, 72, 132) relevant for spherical viruses and the number of the building blocks in the cluster. The size of these Keplerate clusters can be tailored by varying the type of connections between the pentagons by means of different spacers.

9.
Angew Chem Int Ed Engl ; 38(21): 3241-3245, 1999 Nov 02.
Article in English | MEDLINE | ID: mdl-10556915

ABSTRACT

A novel exchange between ligands and/or guest molecules can be accomplished in giant molecular spheres (an example is shown in the picture) which are in equilibrium with the corresponding giant baskets in solution.

10.
Inorg Chem ; 35(6): 1674-1679, 1996 Mar 13.
Article in English | MEDLINE | ID: mdl-11666390

ABSTRACT

A wide range of N-substituted mono- and dihydroxamic acids undergo oxygen abstraction on reaction with V(III), V(IV), and Mo(V) compounds to form hydroxamates of V(V) and Mo(VI) respectively together with the corresponding amides and diamides. The molybdenyl and vanadyl hydroxamates form metal-oxygen clusters under FABMS conditions. The X-ray crystal structures of [MoO(2){CH(3)(CH(2))(n)()C(O)N(C(6)H(5))O}(2) (1 and 2) (n = 4, 5) show monomeric structures with structural trans effects and consequent weakening of the Mo-O(ligand) bonds which may account for the tendency to form clusters in FABMS. In constrast, the electrospray MS of the vanadyl dihydroxamates, VO(OH)[PhN(O)C(O)(CH(2))(n)()C(O)N(O)Ph] (n = 3, 5) and VO(OH)[p-CH(3)C(6)H(4)N(O)C(O) (CH(2))(n)()C(O)N(O)C(6)H(4)-CH(3)) (n = 2, 4) show the presence of dimers in solution.

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