Caesium in high oxidation states and as a p-block element.
The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry, rooted in the atomic shell structure. Within compounds, Group I elements, for example, invariably assume the +1 oxidation state, and their chemical properties differ completely from those of the p-block elements. These general rules govern our understanding of chemical structures and reactions. Here, first-principles calculations show that, under pressure, caesium atoms can share their 5p electrons to become formally oxidized beyond the +1 state. In the presence of fluorine and under pressure, the formation of CsF(n) (n > 1) compounds containing neutral or ionic molecules is predicted. Their geometry and bonding resemble that of isoelectronic XeF(n) molecules, showing a caesium atom that behaves chemically like a p-block element under these conditions. The calculated stability of the CsF(n) compounds shows that the inner-shell electrons can become the main components of chemical bonds.
1] Materials Research Laboratory, University of California, Santa Barbara, California 93106-5050, USA and [2] Beijing Computational Science Research Center, Beijing 10084, China.
Mao-sheng
MS
Miao
D002586:Cesium / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004355:Drug Stability; D004583:Electrons; D005461:Fluorine / Q000737:chemistry*; D010084:Oxidation-Reduction
D002586:Cesium; D005461:Fluorine