Elektronische Struktur und magnetische Anisotropie eines ungesättigten Cyclopentadienyleisen(I)‐Komplexes mit 15 Valenzelektronen

The 15 valence-electron iron(I) complex [CpArFe(IiPr2Me2)] ( 1 , CpAr=C5(C6H4-4-Et)5; IiPr2Me2=1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene) was synthesized in high yield from the FeII precursor [CpArFe(μ-Br)]2. 57Fe Mössbauer and EPR spectroscopic data, magnetic measurements, and ab initio ligand-field calculations indicate an S= 3/2 ground state with a large negative zero-field splitting. As a consequence,  1  features magnetic anisotropy with an effective spin-reversal barrier of Ueff=64 cm−1. Moreover,  1  catalyzes the dehydrogenation of N,N-dimethylamine–borane, affording tetramethyl-1,3-diaza-2,4-diboretane under mild conditions

Experimental and Theoretical Charge Density Studies of 8-Hydroxyquinoline Cocrystallized with Salicylic Acid

The experimental electron density distribution (EDD) in 8-hydroxyquinoline cocrystallized with salicylic acid, 1, has been determined from a multipole refinement of high-resolution X-ray diffraction data collected at 100 K. The experimental EDD is compared with theoretical densities resulting from high-level ab initio and BHandH calculations using Atoms in Molecules theory. 1 crystallizes in the triclinic crystal system, and the asymmetric unit consists of a neutral salicylic acid molecule, a salicylate anion, and an 8-hydroxyquinolinium cation exhibiting a number of inter- and intramolecular hydrogen bonds and π–π interactions. Topological analysis reveals that π–π interactions are of the “closed-shell” type, characterized by rather low and flat charge density. In general, the agreement of the topological values (ρbcp and 2ρbcp) between experiment and theory is good, with mean differences of 0.010 e Å–3 and 0.036 e Å–5, respectively. The energetics of the π–π interactions have been estimated, and excellent agreement is observed between the relative energy and the strength of π-stacking derived from the Espinosa approach, with an average difference of only 4.4 kJ mol–1