Abstract The reactions of SiF 2/SiF 4 with amines, phosphines and various halomethanes were studied. The results show that in the presence of strong Lewis base (Et 3 N, HNEt 2, PR 3, PR 2 Cl), SiF 2 inserts initially into SiF 4 to form Si 2 F 6, which was followed by subsequent reactions leading to products containing SiF 3 groups. This is the first report of the insertion of SiF 2 into SiF 4. When the reactants were a weaker base (such as RPCl 2, ...