Multinuclear Magnetic Resonance Investigation of Crystalline Alkali Molybdates.

A variety of crystalline alkali molybdate phases are characterized by (23)Na, (133)Cs, and (95)Mo magic-angle-spinning nuclear magnetic resonance (MAS NMR) to provide spectroscopic handles for studies of devitrification products in borosilicate nuclear waste glasses. The NMR parameters obtained from line-shape simulations are plotted as a function of various structural parameters to discern trends that may prove useful in the determination of unknown phases. These are applied to Cs3Na(MoO4)2, the most common precipitate found in cesium- and molybdenum-bearing model nuclear waste glasses, the crystal structure of which has not yet been determined, to provide structural constraints that may guide the refinement of powder X-ray diffraction data.

Local and average structure in zinc cyanide: toward an understanding of the atomistic origin of negative thermal expansion.

Neutron diffraction at 11.4 and 295 K and solid-state (67)Zn NMR are used to determine both the local and the average structures in the disordered, negative thermal expansion (NTE) material, Zn(CN)2. Solid-state NMR not only confirms that there is head-to-tail disorder of the C≡N groups present in the solid, but yields information about the relative abundances of the different Zn(CN)4–n(NC)n tetrahedral species, which do not follow a simple binomial distribution.

Characterisation of heterogeneous molybdate and chromate phase assemblages in model nuclear waste glasses by multinuclear magnetic resonance spectroscopy.

A series of sodium borosilicate glasses containing cesium, molybdenum, and chromium was prepared to investigate the partitioning of chromium amongst the glass and phase-separated crystalline molybdates. The precipitates were examined by (133)Cs, (23)Na, and (95)Mo MAS NMR, revealing a phase assemblage consisting of Na(2)MoO(4), Na(2)MoO(4)·2H(2)O, Cs(2)MoO(4), Cs(2)CrO(4), CsNaMoO(4)·2H(2)O, and Cs(3)Na(MoO(4))(2). (133)Cs MAS NMR indicates random substitution of Cr into the Mo sites of Cs(3)Na(MoO(4))(2) and provides a quantitative assessment of Cr incorporation.

Characterising lone-pair activity of lead(II) by 207Pb solid-state NMR spectroscopy: coordination polymers of [N(CN)2]- and [Au(CN)2]- with terpyridine ancillary ligands.

A series of lead(II) coordination polymers containing [N(CN)(2)](-) (DCA) or [Au(CN)(2)](-) bridging ligands and substituted terpyridine (terpy) ancillary ligands ([Pb(DCA)(2)] (1), [Pb(terpy)(DCA)(2)] (2), [Pb(terpy){Au(CN)(2)}(2)] (3), [Pb(4'-chloro-terpy){Au(CN)(2)}(2)] (4) and [Pb(4'-bromo-terpy)(μ-OH(2))(0.5){Au(CN)(2)}(2)] (5)) was spectroscopically examined by solid-state (207)Pb MAS NMR spectroscopy in order to characterise the structural and electronic changes associated with lead(II) lone-pair activity. Two new compounds, 2 and [Pb(4'-hydroxy-terpy){Au(CN)(2)}(2)] (6), were prepared and structurally characterised.