Main Group and Transition Metal-Selenolate Complexes: Rings to Clusters

Rhodium and Iridium Complexes of Anionic Thione and Selone Ligands Derived from Anionic N-Heterocyclic Carbenes

The lithium salts of anionic N‐heterocyclic thiones and selones [{(WCA‐IDipp)E}Li(toluene)] (1: E=S; 2: E=Se; WCA=B(C₆F₅)₃, IDipp=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene), which contain a weakly coordinating anionic (WCA) borate moiety in the imidazole backbone were reacted with Me₃SiCl, to furnish the silylated adducts (WCA‐IDipp)ESiMe₃ (3: E=S; 4: E=Se). The reaction of the latter with [(η⁵‐C₅Me₅)MCl₂]₂ (M=Rh, Ir) afforded the rhodium(III) and iridium(III) half‐sandwich complexes [{(WCA‐IDipp)E}MCl(η⁵‐C₅Me₅)] (5–8). The direct reaction of the lithium salts 1 and 2 with a half or a full equivalent of [M(COD)Cl]₂ (M=Rh, Ir) afforded the monometallic complexes [{(WCA‐IDipp)E}M(COD)] (9–12) or the bimetallic complexes [μ₂‐{(WCA‐IDipp)E}M₂(COD)₂(μ₂‐Cl)] (13–16), respectively. The bonding situation in these complexes has been investigated by means of density functional theory (DFT) calculations, revealing thiolate or selenolate ligand character with negligible metal‐chalcogen π‐interaction.

Tetrametallic Thorium Compounds with Th4E4 (E = S, Se) Cubane Cores

Tetrametallic thorium compounds with a Th₄E₄ core (E = S, Se) having a distorted cubane structure can be prepared by ligand-based reductions of elemental E with thorium chalcogenolates, prepared by in situ oxidation of Th metal with a 3:1 mixture of PhEEPh and F₅C₆EEC₆F₅. Four compounds, (py)₈Th₄S₄(μ₂-SPh)₄(SC₆F₅)₄, (py)₈Th₄S₄(μ₂-SPh)₄(SeC₆F₅)₄, (py)₈Th₄Se₄(μ₂-SePh)₄(SeC₆F₅)₄, and (py)₈Th₄Se₄(μ₂-SePh)₄(SC₆F₅)₄, were isolated and characterized by NMR spectroscopy and X-ray diffraction. These compounds clearly demonstrate the chemical impact of ring fluorination, with the less-nucleophilic EC₆F₅ ligands occupying the terminal binding sites and the EPh ligands bridging two metal centers. For this series of compounds, crystal packing and intermolecular π···π and H-bonding interactions result in a consistent motif and crystallization in a body-centered tetragonal unit cell. Solution-state ⁷⁷Se NMR spectroscopy reveals that the solid-state structures are maintained in pyridine.