The reactions of trialkyl borates B(OR)3 (R = Me, i-Pr) with dimethylphenylsilyllithium gave lithium alkoxytris(dimethylphenylsilyl)borates 1a,b. X-ray crystallographic analysis showed that 1a,b were obtained as a contact ion pair and a solvent-separated ion pair, respectively. The 11B and 29Si chemical shifts as well as the Si–B and B–O bond lengths of 1a,b and related compounds largely change, depending on the numbers of silyl and alkoxy substituents.
