  Two novel 112-type palladium doped iron arsenides were synthesized and
identified using comprehensive studies involving synchrotron x-ray diffraction
and x-ray absorption near edge structure (XANES) experiments. Whereas in-plane
arsenic zigzag chains were found in 112-type superconducting iron arsenide,
Ca1-xLaxFeAs2 with maximum Tc = 34 K, deformed arsenic network structures
appeared in 112-type materials such as longitudinal arsenics zigzag chains in
CaFe1-yPdyAs2 (y ~ 0.51) and arsenic square sheets constructed via hypervalent
bonding in Ca1-xLaxFe1-yPdyAs2 (x ~ 0.31, y ~ 0.30). As K-edge XANES spectra
clarified the similar oxidization states around FeAs4 tetrahedrons, expecting
us the possible parents for high Tc 112-type iron arsenide superconductors.
