[closo-B₁₀H₈-1,10-(CN)₂]^2– as a Conduit of Electronic Effects: Comparative Studies of Fe···Fe Communication in [{(η⁵-Cp)(dppe)Fe}₂{μ₂-(NC-X-CN)}]ⁿ⁺ (n = 0, 2)

Abstract

Electronic communication between Fe centers in the diiron complexes [{(ηand −C 2 B 10 H 10 − was investigated by spectroscopic (UV−vis and IR), electrochemical (CV and DPV), and single-crystal XRD methods. All experimental results were supported by a DFT computational analysis (B3LYP/Def2SVP) of model complexes that included two other closo-boranes: X = −C 2 B 8 H 8 − and [−B 12 H 10 −] 2− . The DFT analysis focused on the geometry, electronic excitations, IR spectra, charge and spin delocalization, and intramolecular spin−spin exchange interactions in the series of all six complexes and their singly and doubly oxidized analogues. The results demonstrate that [closo-B 10 H 8 -1,10-diyl] 2− has the best ability among the closo-boranes to mediate electronic effects similar to those of 1,4phenylene. This is evident from the observed separation of one-electron-oxidation waves (∼70 mV) and comparable S−T energy gaps in the doubly oxidized species. Article pubs.acs.org/Organometallics

Structure of a Fe4O6-Heteraadamantane-Type Hexacation Stabilized by Chelating Organophosphine Oxide Ligands

“…tively low stability in comparison to those of other dinitriles NC-X-CN, for which the formation of byproduct I was not observed [8].…”

“…The components necessary to the formation of I could also be formed by the decomposition of the [(Cp)(dppe)Fe] + fragment in the intended dinuclear complex. The CN-Fe coordination bond in the dinuclear complex of [closo-1,12-C 2 B 10 H 10 -1,12-(CN) 2 ] has a relatively low stability in comparison to those of other dinitriles NC-X-CN, for which the formation of byproduct I was not observed [8].…”

“…An attempted preparation of a dinuclear complex [{(Cp)(dppe)Fe} 2 (closo-1,12-C 2 B 10 H 10 -1,12-(CN) 2 )](PF 6 ) 2 [8] gave minor quantities of transparent, orange, single crystals suitable for a single crystal X-ray measurement. The refined structure did not match the intended complex.…”

“…Following the reported procedure [8], a mixture of [closo-1,12-C 2 B 11 H 10 (CN) 2 ] (0.011 g, 0.06 mmol, 1.0 eq. ), [(Cp)(dppe)FeCl] (0.063 g, 0.11 mmol, 2.1 eq.)…”

“…After three weeks, several transparent, brown, block-shaped single-crystals emerged (<3 mg), and their structure was determined by single-crystal XRD analysis to reveal that of compound I. The remaining solution was evaporated, and the resulting material was purified by precipitation from CH 2 Cl 2 solution with petroleum ether giving the intended [{(Cp)(dppe)Fe} 2 (closo-1,12-C 2 B 10 H 10 -1,12-(CN) 2 )](PF 6 ) 2 in 58% yield as an orange polycrystalline powder [8].…”