Geometrische und chemische Koordination

Abstract

AbstractTwo geometrical concepts of coordination (Frank and Kasper 1958 and Ruban 1985) are identical with Niggli's (1927) concept of “Wirkungsbereich”. The geometrical coordination number can be reduced to a chemical coordination number which includes the number of weak bonds in the case of irregular coordinations or molecular compounds.Bond lengths in solid CO2, calcite, magnesite, rhodochrosite, siderite, smithonite and dolomite are discussed. Exceptionally short C – O-bonds in calcite are due to the large distance between carbonate layers which is caused by the larger ionic radius of Ca2+.