Coordination versus Insertion: On the Interaction of 5 d‐Transition Metal Carbonyl Clusters with Silver(I)

Abstract

The title silver(I) complex salts [Ag{Re₂ (CO)₁₀ }{Re(CO)₅ }₂ ]⁺ [Al(OR^F )₄ ]^- (AgRe₄ ; OR^F =-OC(CF₃ )₃ ) and [Ag{Ir₄ (CO)₁₂ }₂ ]⁺ [Al(OR^F )₄ ]^- (AgIr₈ ) form upon reaction of Ag⁺ [Al(OR^F )₄ ]^- and the transition metal carbonyls (TMCs) Re₂ (CO)₁₀ and Ir₄ (CO)₁₂ respectively. The solid-state structure of the AgRe₄ cluster shows an unexpected asymmetric coordination motif, wherein the silver(I) cation has inserted into the Re-Re bond of one Re₂ (CO)₁₀ moiety, while the other dirhenium carbonyl coordinates only over one metal atom towards the silver(I) cation. The AgIr₈ cluster is formed by the edge-on coordination of two Ir₄ tetrahedra and the silver cation in a D₂ symmetric fashion with a torsion angle of 46.5°. QTAIM analysis shows bond paths between the silver atom and the nearby metal atoms in all cases, whereas only the non-inserted Re₂ (CO)₁₀ moiety shows additional bond paths between the carbonyl ligands and the silver cation. In addition, the insertion of the Ag⁺ cation into the Re-Re bond in Re₂ (CO)₁₀ removes the bond path between the two rhenium atoms. The EDA-NOCV analysis suggests an increase of the interaction energy between the silver(I) cation and the respective metal carbonyls from the metal centered transition metal carbonyl (TMC) donors W(CO)₆ <Re₂ (CO)₁₀ <Os₃ (CO)₁₂ <Ir₄ (CO)₁₂ . In all cases, the dominating orbital interaction is σ-donation [TMC]→Ag⁺ ←[TMC].