Organometallic motifs in the structures of solid state ternary carbides of the late transition metals

Solid state ternary transition metal carbides containing carbon, a middle to late transition metal (Re to Ni), and a highly electropositive multivalent metal such as lanthanide, yttrium, or thorium exhibit a number of structural motifs resembling those in metal carbonyls and other transition metal derivatives of strong -acceptor ligands. This paper presents models for the chemical bonding in the transition metal—carbon subnetworks of the ternary late transition metal carbides LnCoC (Ln=lanthanide), Ln₂ReC₂, Th₂NiC₂, Ln₂FeC₄, Ln₃MC₄ (M=Fe, Co, Ni, Ru, Rh, Os, Ir), Ln₄NiC₅, Ca₄Ni₃C₅, and Er₈Rh₅C₁₂. Carbide ligands present in such materials include terminal C^4– in Th₂NiC₂ and Y₂ReC₂, ₂-C^4– in YCoC or Y₂ReC₂ similar to the central allene carbon atom, 1,2-bridging C ₂ ^4– in Sc₃CoC₄ formally derived from ethylene, ₃-bridging C ₂ ^4– in LnMC₂ (M=Fe, Co, Ni, Ru) formally derived from ethylene, and 1,1-bridging C ₂ ^2– in Ln₂FeC₄ isoelectronic with ₂-CO group in metal carbonyls.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1358–1366, August, 1994.