Yttrium Dihydride Cation [YH<sub>2</sub>(THF)<sub>2</sub>]<sup>+</sup><sub><i>n</i></sub>: Aggregate Formation
and Reaction with (NNNN)-Type Macrocycles
- Publication date
- Publisher
Abstract
Monocationic bis(hydrocarbyl)yttrium
complexes [YR<sub>2</sub>(THF)<sub>2</sub>][A] (R = CH<sub>2</sub>SiMe<sub>3</sub>, CH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>-o-NMe<sub>2</sub>; A = weakly coordinating anion)
underwent hydrogenolysis using dihydrogen or phenylsilane to give
a mixture of polynuclear solvent-stabilized dihydride cations [YH<sub>2</sub>(THF)<sub>2</sub>]<sub><i>n</i></sub>[A]<sub><i>n</i></sub>. The mixture composition as well as the nuclearity <i>n</i> depended on the starting material, solvent, and reaction
conditions. NMR spectroscopic data in solution and X-ray diffraction
data suggested that the main product was tetranuclear, although conclusive
structural data were not obtained. DFT calculations supported a <i>closo</i>-type tetrahedral [YH<sub>2</sub>(THF)<sub>2</sub>]<sub>4</sub><sup>4+</sup> core. The hydridic character of these cations
was revealed by their reaction with benzophenone to give the bis(diphenylmethoxy)
cation [Y(OCHPh<sub>2</sub>)<sub>2</sub>(THF)<sub>4</sub>][AlR<sub>4</sub>]. The reaction of this cluster with the (NNNN)-type macrocycle
Me<sub>4</sub>TACD under dihydrogen gave the dinuclear tetrahydride
dication with quadruply bridging hydride ligands, [Y<sub>2</sub>(μ-H)<sub>4</sub>(Me<sub>4</sub>TACD)<sub>2</sub>][A]<sub>2</sub>, analogous
to the previously characterized lutetium derivative. NH-acidic (Me<sub>3</sub>TACD)H gave the dinuclear dihydride dication [Y<sub>2</sub>(μ-H)<sub>2</sub>(Me<sub>3</sub>TACD)<sub>2</sub>(THF)<sub>2</sub>][A]<sub>2</sub>
