bifluororenylyl group. Methylphenyl(phenylethynyl)(2-phenylpropyl)tin and phenylethynyltrimethyltin react with LiAlH4; the phenylethynyl—tin bond is cleaved but the formed phenylacetylene and organotin hydride react together to give the expected adduct. Bifluorenyl-9-ylmethylneophylphenyltin is converted with LiAlH4, into 1,2-dimethyl-1,2-dineophyl-1,2-diphenylditin.