Ynone Co-Coordination at a Nickel Borane Complex: An Assessment of Secondary Coordination Sphere Effects

Secondary coordination sphere ligand effects can be used
to direct
or organize small molecule substrates at a metal center. Herein, we
assess the bifunctional ambiphilic diphosphine, tri-tert-butylboranyldiphosphinoethane (ttbbpe)
and its ability to influence stereoselective substrate coordination,
while appended to nickel. This report takes a synthetic/computational
approach to test the impacts and limitations associated with ligand-directed
substrate coordination using [Ni(ttbbpe)(η2:η2-COD)] (COD = 1,5-cyclooctadiene) and
ynones (alkynes having an α-carbonyl group at the propargylic
position) as model substrates.