Reduced Arene Complexes of Scandium
Priyabrata Ghana, Alexander Hoffmann, Thomas P. Spaniol, Jun Okuda
Abstract
Abstract Alkali metal naphthalenide or anthracenide reacted with scandium(III) anilides [Sc(X){N( t Bu)Xy} 2 (thf)] (X=N( t Bu)Xy ( 1 ); X=Cl ( 2 ); Xy=C 6 H 3 ‐3,5‐Me 2 ) to give scandium complexes [M(thf) n ][Sc{N( t Bu)Xy} 2 (RA)] (M=Li–K; n =1–6; RA=C 10 H 8 2− ( 3‐Naph‐K ) and C 14 H 10 2− ( 3‐Anth‐M )) containing a reduced arene ligand. Single‐crystal X‐ray diffraction revealed the scandium(III) center bonded to the naphthalene dianion in a σ 2 :π‐coordination mode, whereas the anthracene dianion is symmetrically attached to the scandium(III) center in a σ 2 ‐fashion. All compounds have been characterized by multinuclear, including 45 Sc NMR spectroscopy. Quantum chemical calculations of these intensely colored arene complexes confirm scandium to be in the oxidation state +3. The intense absorptions observed in the UV/Vis spectra are due to ligand‐to‐metal charge transfers. Whereas nitriles underwent C−C coupling reaction with the reduced arene ligand, the reaction with one equivalent of [NEt 3 H][BPh 4 ] led to the mono‐protonation of the reduced arene ligand.