Kinetics of the Template Synthesis and Acidic Decomposition of the Methylboron‐Capped Iron(II) Tris‐heptoximate: Dramatic Changes in a Series of Alicyclic α‐Dioximate Ligand Synthons

Abstract

Reaction of the template synthesis of the methylboron-capped iron(II) tris-heptoximate clathrochelate on Fe 2 + ion as a matrix was found to proceed in the quantitative yield in diluted aqueous-organic solutions. This complex is intensively colored in the visible range, whereas the initial ligand synthons are optically silent, thus allowing to photometric study the kinetics of its synthesis and acidic decomposition reactions. Template condensation of the corresponding chelating and capping ligand synthons gave a solid form of this macrobicyclic complex, which was characterized using modern spectral methods and by the single-crystal X-ray diffraction (XRD) experiment. Kinetic schemes and parameters of the aforemen-tioned reactions for the methylboron-capped clathrochelates, the derivatives of six-(H 2 Nx), seven-(H 2 Gx) and eight(H 2 Ox)membered alicyclic α-dioximes, are dramatically affected by their alicyclic ring size. If the general schemes of their formation persist, those for H 2 Nx and H 2 Gx contain a rate-determining stage, whereas that for H 2 Ox has three initial consecutive stages with close rates. Passing from H 2 Nx to H 2 Gx caused a decrease in the synthesis reaction rates of their macrobicyclic derivatives by approximately three orders of magnitude. These kinetic effects were explained using the XRD data for the initial α-dioximes and for their methylboron-capped macrobicyclic derivatives.

Multistep synthesis and X-ray structures of carboxyl-terminated hybrid iron(ii) phthalocyaninatoclathrochelates and their postsynthetic transformation into polytopic carboranyl-containing derivatives

“…All ribbed cyclohexane substituents in the tris-nioximate semiclathrochelate molecules show a twist conformation, characteristic of the macrobicyclic iron( ii ) complexes, the derivatives of the same α-dioximate synthon. 30…”

“…All ribbed cyclohexane substituents in the tris-nioximate semiclathrochelate molecules show a twist conformation, characteristic of the macrobicyclic iron(II) complexes, the derivatives of the same α-dioximate synthon. 30 The cross-linking heptacoordinate zirconium and hafnium (IV) cations in all four phthalocyaninatoclathrochelate molecules under study coordinate three chelating nioximate fragments through the oxygen atoms of their donor oxime groups. These ions also coordinate four nitrogen atoms of a distal phthalocyaninate ligand synthon.…”