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

The title silver(I) complex salts [Ag{Re2(CO)10}{Re(CO)5}2]+[Al(ORF)4]− (AgRe4; ORF = -OC(CF3)3) and [Ag{Ir4(CO)12}2]+­[Al(ORF)4]− (AgIr8) form upon reaction of Ag+[Al(ORF)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°. The 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 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].