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(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°. 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].