Summary:(Pentaalky1iditin) lithiums are demonstrated to be present in preparations of (trialky1tin) lithium reagents (from the trialkyltin halide and lithium in tetrahydrofuran) by direct observation ('''Sn NMR) and alkylation to R, Sn, R'(R= methyl, n-propyl, isopropyl; R'= cyclohexyl, methyl). Cyclohexylation of (iC, H,), Sn, Li proceeds by a free radical route. The R5Sn, Li species are considered to arise by oxidative addition of R, SnLi to R, Sn, formed ...