The Crystal-Chemical Role of Alkylmalonate Ions in the Structure of Coordination Polymers

Abstract

Alkyl-substituted (methyl, ethyl, diethyl) malonate ions (Rmal²⁻) are found to display 13 topologically different types of coordination with respect to d- or f-metals A. The factors that cause Rmal²⁻ ions to choose one possible coordination are discussed; valence angle C—C—C in a malonate ion lies within 102°–119° range and depends linearly on the dihedral angle between the planes of two carboxyl groups. When coordinated with metal atom A, alkyl-substituted malonate ions are found to produce six-membered metallocycles of bath conformation. It is established that increasing the volume of R substituents in Rmal²⁻ ions strengthens the repulsion among carboxyl groups and alkyl substituents and reduces the C—C—C angle.