Template synthesis, X-ray structure, spectral and redox properties of the paramagnetic alkylboron-capped cobalt(II) clathrochelates and their diamagnetic iron(II)-containing analogs

Perfluoroarylation of Iron(II) Di‐ and Hexaiodoclathrochelates – Synthesis, X‐ray Structure, and Properties of the First Cage Complexes with Inherent Pentafluoro­phen­yl Substituent(s)

“…Therefore, the functionalization of the trisdioximate clathrochelate framework with up to six pentafluorophenyl ribbed substituents resulted in no stabilization of the reduced anionic iron(I)‐containing macrobicyclic species. The same results were observed earlier10 for the tris‐α‐benzyldioximate clathrochelate [FeBd 3 (B n ‐C 4 H 9 ) 2 ], for which the Fe 2+/+ reduction potential was shifted in the cathodic range by approximately 550 mV compared with that of its perfluoroarylated analog [Fe{(C 6 F 5 ) 2 Gm} 3 (B n‐ C 4 H 9 ) 2 ].…”

“…The I c / I a current ratio for the direct and backward processes is equal to 1, so the oxidized clathrochelate species are stable on the CV timescale, and no substantial structural and chemical transformations of these species are observed. The electrochemical behavior of the hexa(pentafluorophenyl)ated iron(II) clathrochelate is similar to that of its hexaphenyl‐containing analog [FeBd 3 (B n ‐C 4 H 9 ) 2 ],10 except for an anodic shift of the Fe 2+/3+ oxidation potential by approximately 600 mV (Table 1).…”

“…In contrast, the functionalizing substituents in ribbed chelate α-dioximate fragments of their clathrochelate frameworks substantially affect the physicochemical (in particular, redox) properties of these cage complexes. The I c /I a current ratio for the direct and backward processes is equal to 1, so the oxidized clathrochelate species are stable on the CV timescale, and no substantial structural and chemical transformations of these speciesareobserved.Theelectrochemicalbehaviorofthehexa-(pentafluorophenyl)ated iron(II) clathrochelate is similar to that of its hexaphenyl-containing analog [FeBd 3 (Bn-C 4 H 9 ) 2 ], [10] except for an anodic shift of the Fe 2+/3+ oxidation potential by approximately 600 mV ( Table 1). This result is consistent with the strong electron-with-drawing effect of the perfluoroaryl substituent.…”

A New Series of Cobalt and Iron Clathrochelates with Perfluorinated Ribbed Substituents

“…In addition, a dynamic Jahn–Teller exchange between three possible distorted molecular structures of each complex at room temperature leads to partial averaging of both the Fermi and dipolar contributions to the paramagnetic shifts. 17…”

“…Both g and hyperfine tensors are rhombic, and their values are characteristic of the low-spin cobalt(II) clathrochelates. 17 Note that high-spin cobalt(II) clathrochelates are EPR-silent in the X-band as a result of a very large negative zero-field splitting. 18…”