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Carbonate-assisted hydrolysis of Y or Yb I I I ions in the presence of the trivacant Wells-Dawson polyoxo-anion, α-[P 2 W 1 5 O 5 6 ] 1 2 - , produced two polyoxometalate-supported Y- or Yb I I I -hydroxo/oxo clusters, which have been characterized by single-crystal X-ray structure determination. The structure of the Y complex consists of a distorted Y 4 (OH) 4 cubane cluster encapsulated by two lacunary α-[P 2 W 1 5 O 5 6 ] 1 2 - units, while the Yb cluster features a hexametallic core centered around a μ 6 -oxo atom with each Yb I I I 3 triangular face capped by an oxo or a hydroxo group. Magnetization measurements of the ytterbium(III) derivative suggested that intermolecular dipolar exchange is present at low temperatures (below 15 K). Despite its absence in the structures themselves, control experiments show that carbonate not only functions in the hydrolysis, it also influences the structure of the complexes by complexation to yttrium and the f-block elements.

The tetrameric macrocycle [(P(mu-NtBu))2(1,4-(NH)2C6H4)]4, obtained from the reaction of the phosphazane dimer [ClP(mu-NtBu)]2 with p-phenylenediamine, has an unusual folded conformation in the solid state and contains a roughly tetrahedral arrangement of endo N-H groups for the potential coordination of anions.

Reaction of A-alpha-PW(9)O(34)(9)(-) with YCl(3) in an aqueous Na(2)CO(3) solution produces a dianion-encapsulated A-type sandwich polyoxometalate, (YOH(2))(3)(CO(3))(A-alpha-PW(9)O(34))(2)(11)(-). The X-ray structure of this complex reveals that three Y(III) ions are sandwiched between two A-alpha-PW(9)O(34)(9)(-) moieties and that a carbonate dianion is encapsulated in the same plane as the three Y(III) atoms. The oxygen atoms of the CO(3)(2)(-) are sitting at the midpoints of the sides of the triangle formed by the three Y(III) ions. (31)P and (13)C NMR studies confirm that this complex is significantly more stable than the analogous A-type sandwich polyoxometalates containing divalent metals.

7Li nuclear magnetic resonance (NMR) studies have been performed to investigate magnetic properties and spin dynamics of Mn3+ (S = 2) spins in the giant polyoxometalate molecule {Mn40W224}. The 7Li-NMR line width is proportional to the external magnetic field H as expected in a paramagnetic state above 3 K. Below this temperature the line width shows a sudden increase and is almost independent of H, which indicates freezing of the local Mn3+ spins. The temperature dependence of T1 for both 1H and 7Li reveals slow spin dynamics at low temperatures, consistent with spin freezing. The slow spin dynamics is also evidenced by the observation of a peak of 1/T2 around 3 K, where the fluctuation frequency of spins is of the order of ~200 kHz. An explicit form of the temperature dependence of the fluctuation frequency of Mn3+ spins is derived from the nuclear relaxation data.

The first organic-inorganic hybrid complexes between CB[n] and polyoxometalates not only display a surprisingly high structural complementarity, the right pairing also allows their chemical and physical properties to be coupled, as illustrated by two examples.

The first biomimetic total syntheses of ent-nakorone, ent-durgamone, and ent-abudinol B were accomplished by combining features of tandem polyepoxide cyclization with biomimetic polyene cyclization. The present biomimetic synthesis route offers efficient access to these marine natural products. In addition, the synthesis of the tetrasubstituted alkene of ent-abudinol B demonstrates the application of palladium-catalyzed cross-coupling of two different polycyclic ketones via the corresponding vinyl triflates, followed by partial hydrogenation of the resulting conjugated diene.

Static and dynamical properties of Fe3+ (3d5; S = 5/2) spins in geometrically frustrated magnetic molecule Fe30 have been investigated by nuclear magnetic resonance (NMR) in the temperature range T = 0.1–300 K From a measurement of nuclear spin-lattice relaxation rates as a function of temperature, the fluctuation frequency of Fe3+ spins is found to decrease with decreasing temperature, indicating spin freezing at low temperatures.

The assembly of a tetradeca-manganese magnetic cluster [Mn(14)W(48)O(192)H(20)](26-), containing two high spin Mn(7) cores and supported exclusively by isopolytungstate ligands, demonstrates the promising perspective of using "defect" isopolyanions as ligands/synthons to construct large aggregated structures and model the surface deposition of molecular magnets.

We show that intramolecular exchange disorder recently found in the geometrically frustrated magnetic molecules {Mo(72)Fe(30)} and {Mo(72)Cr(30)} leads, in a classical Heisenberg model description, to spin freezing and slow magnetization dynamics reminiscent of spin glass behaviour. Also we suggest that our low temperature and low magnetic field nuclear magnetic resonance (NMR) measurements on {Mo(72)Fe(30)}, showing rapid and strong broadening of the proton line width on cooling below 600 mK, are evidence for a crossover from paramagnetic behaviour to a frozen spin configuration. Similar broadening is observed in {Mo(72)Cr(30)}. This observed effect is consistent with our theory of spin freezing and slow magnetization dynamics in these systems due to exchange disorder.