Donor layer-acceptor chain formation in the LaNiGe2 structure: A crystallographic and computational study

Synthesis, and single-crystal X-ray diffraction and computational studies were carried out for the title compound. LaNiGe2 crystallizes in the orthorhombic lattice Cmcm (a = 4.3040(6) Angstrom, b = 16.892(10) Angstrom, c = 4.2367(5) Angstrom, Z = 4). It consists of a Ni-capped Ge square lattice and Ge zigzag chains. A unique structural feature is the formation of the square lattice by the more electronegative Ge instead of by Ni atoms as in several other phases such as La3Ni4Ge4. Computational analysis indicates that the Ge square lattice acts as an electron donor while the Ge zigzag chain acts as electron acceptor. A donor-acceptor interaction similar to that in the CaBe2Ge2 phase stabilizes the Ge square lattice.