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

Abstract

Metal-containing heteraadamantanes are compounds of interest due to their spectroscopic and magnetic properties, which make them promising materials for non-linear optics and semiconductors. Herein we report the comprehensive structural characterization of a new coordination compound of the formula [(µ-OH′)2(µ-OH″)4(O = P(Ph2)CH2CH2(Ph2)P = O)4{Fe(t-BuOH)}4](PF6)4(Cl)2 with the chelating ligand Ph2P(O)-CH2CH2-P(O)Ph2. The compound crystallizes as a polynuclear metal complex with the adamantane-like core [Fe4O6] in the space group I-43d of a cubic system. The single-crystal XRD analysis showed that the crystal contains one symmetrically independent octahedrally coordinated Fe atom in the oxidation state +3. The adamantine-like scaffold of the Fe complex is formed by hydroxy bridging oxygen atoms only. Hirshfeld surface analysis of the bridging oxygen atoms revealed two types of µ-OH groups, which differ in the degree of exposure and participation in long-range interactions. Additionally, the Hirshfeld surface analysis supported by the enrichment ratio calculations demonstrated the high propensity of the title complex to form C-H…Cl, C-H…F and C-H…O interactions.

Keywords

• heteraadmantane
• organophosphine oxide ligand
• single-crystal
• Hirshfeld surface analysis
• enrichment ratio