Hydroboration Kinetics. 6.1 Hydroboration of Alkenes with 9-Borabicyclo[3.3.1]nonane Dimer and 9-Borabicyclo[3.3.1]nonane-Lewis Base Complexes in Various Solvents: An Interpretation of the Catalytic Effect of Ether Solvents on the Hydroboration Reaction