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.