Uniaxial negative thermal expansion and metallophilicity in Cu3[Co(CN)6]

We report the synthesis and structural characterisation of the molecular framework copper(I)hexacyanocobaltate(III), Cu3[Co(CN)6], which we find to be isostructural to H3[Co(CN)6] and the colossalnegative thermal expansion material Ag3[Co(CN)6]. Using synchrotron X-ray powder diffraction measurements,we find strong positive and negative thermal expansion behaviour respectively perpendicular and parallel to thetrigonal crystal axis:α= 25.4(5) MKa−1andα= − 43.5(8) MKc−1. These opposing effects collectively result in avolume expansivityα= 7.4(11) MKV−1that is remarkably small for an anisotropic molecular framework. Thisthermal response is discussed in the context of the behaviour of the analogous H- and Ag-containing systems.We make use of density-functional theory with many-body dispersion interactions (DFT + MBD) todemonstrate that Cu+…Cu+metallophilic (‘cuprophilic’) interactions are significantly weaker in Cu3[Co(CN)6]than Ag+…Ag+interactions in Ag3[Co(CN)6], but that this lowering of energy scale counterintuitively translatesto a more moderate—rather than enhanced—degree of structural flexibility. The same conclusion is drawn fromconsideration of a simple GULP model, which we also present here. Our results demonstrate that stronginteractions can actually be exploited in the design of ultra-responsive materials if those interactions are set upto act in tension

ECONOMIC EQUALITY AND VICTORY IN WAR: AN EMPIRICAL INVESTIGATION

This paper tests a simple hypothesis: that given the occurrence of war between two countries, the country that is more egalitarian at the moment of military decision is likely to emerge the victor. First, we examine cases where comparative economic inequality can be measured directly, using the nearly comprehensive global datasets of the University of Texas Inequality Project for the years 1963-1999. Second, we examine cases where reasonable inferences about comparative economic inequality may be drawn by analogy to UTIP measurements or from other political and economic evidence, including both bi-national wars and larger wars where there existed clear pair-wise fronts. Third, we discuss selected cases where inferences may be drawn from literary or historical sources. We find, all in all, that the evidence for an egalitarian victory proposition is remarkably strong.