Structure and bonding in lithium ruthenate, Li2RuO3

The metallic lithium ruthenate Li2RuO3 was prepared from Li2CO3 and RuO2 at high temperature; its structure was studied by powder neutron diffraction and found to be in agreement with that previously published on the basis of powder X-ray diffraction. Li2RuO3 has a monoclinic unit cell (C2/c; a = 4.9116A˚,b = 8.7586A˚,c = 9.8544A˚, β = 100.08°); its structure closely resembles that of β-Li2SnO3, but there is a different stacking of alternating, close-packed Li andLiM2 (M =Ru, Sn) layers. The HeI photoelectron spectrum of Li2RuO3 shows an intense Fermi edge, which implies a high electronic density of states at the Fermi energy. Li2RuO3 is paramagnetic and obeys the Curie-Weiss law above 80 K (μeff = 1.83 μB, O = −167 K). A semiempirical band model for Li2RuO3 accounts for its metallic conductivity, photoelectron spectrum, magnetic behavior, and unusual stacking sequence. Electrochemical delithiation of Li2RuO3 led to a rearrangement of Ru within layers that stabilizes additional RuRu bonding.