A Strong Dependence of the P-P Bond Length on the Transition Metal Component in ThCr2Si2-Type Phosphides CaM2P2 (M = Fe, Ni): The Influence of d Band Position and sp * Mixing

摘要

An analysis of the bonding situation in CaM2P2 (M=Fe, Ni) with ThCr2Si2 structure is made in terms of DOS and COOP plots. The main contributions to covalent bonding are due to M-P and P-P interactions in both compounds. Particularly, the interlayer P-P bonding by variation in the transition metal is examined in more detail. It turns out that the shorter P-P bonds in CaNi2P2 form as a result of the decreasing electron delocalization into sp * of P2 due to the weaker bonding interaction between the metal d and sp * as the metal d band is falling from Fe to Ni.