Solvent‐Dependent Structure of the I3− Ion Derived from Photoelectron Spectroscopy and Ab Initio Molecular Dynamics Simulations

Ab initio molecular dynamics (MD) simulations of the solvation of LiI₃ in four different solvents (water, methanol, ethanol, and acetonitrile) are employed to investigate the molecular and electronic structure of the I₃^? ion in relation to X‐ray photoelectron spectroscopy (XPS). Simulations show that hydrogen‐bond rearrangement in the solvation shell is coupled to intramolecular bond‐length asymmetry in the I₃^? ion. By a combination of charge analysis and I 4 d core‐level XPS measurements, the mechanism of the solvent‐induced distortions has been studied, and it has been concluded that charge localization mediates intermolecular interactions and intramolecular distortion. The approach involving a synergistic combination of theory and experiment probes the solvent‐dependent structure of the I₃^? ion, and the geometric structure has been correlated with the electronic structure.     

Diborylated Magnesium Anthracene as Precursor for B2H5−‐Bridged 9,10‐Dihydroanthracene

9,10‐(Bpin)₂‐anthracene ( 3 , HBpin=pinacolborane) was synthesized from 9,10‐dibromoanthracene in a stepwise lithiation/borylation sequence. The reaction of 3 with highly activated magnesium furnished the diborylated magnesium anthracene 4 , which was quenched in situ with ethereal HCl to yield cis‐9,10‐(Bpin)₂‐DHA (cis‐ 5 , DHA=9,10‐dihydroanthracene). Compound cis‐ 5 , in turn, can be reduced with Li[AlH₄] in THF to give its diborate Li₂[cis‐9,10‐(BH₃)₂‐DHA] (Li₂[cis‐ 6 ]). In the crystal lattice, the THF solvate Li₂[cis‐ 6 ] ? 3 THF establishes a dimeric structure with Li‐(μ‐H)‐B coordination modes. Hydride abstraction from Li₂[cis‐ 6 ] with Me₃SiCl yields the B?H?B‐bridged DHA Li[ 7 ]. This product can also be viewed as a unique cyclic B₂H₇^? derivative with a hydrocarbon backbone. Treatment of Li₂[cis‐ 6 ] with the stronger hydride abstracting agent Me₃SiOTf (HOTf=trifluoromethanesulfonic acid) in THF affords the THF diadduct of cis‐9,10‐(BH(OTf))₂‐DHA.