issue contents
February 2011 issue

Cover illustration: A view of the molecular structure of one of the two independent molecules of (5-tert-butylporphyrinato)copper(II) in the crystal. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity. See Senge [Acta Cryst. (2011), C67, m39-m42].
inorganic compounds
A new gadolinium ytterbium trifluoride has been grown for the first time by the Czochralski technique. Although GdF3 and YbF3 both present a high-temperature phase transition, the mixed compound Gd0.81Yb0.19F3 maintains its crystallographic structure upon cooling to room temperature. The grown crystal melts noncongruently at ∼1413 K, it is transparent and colourless, and it has a high density.
The title compound contains Na+ cations within both a six-sided tunnel and a large S-shaped tunnel formed by the manganese oxide framework. The unexpected location of a new Na+ site within the S-shaped tunnel accounts for the observation of an Na stoichiometry greater than 4.