the instant invention provides for novel cationic lipids that can be used in combination with other lipid components such as cholesterol and peg - lipids to form lipid nanoparticles with oligonucleotides . it is an object of the instant invention to provide a cationic lipid scaffold that demonstrates enhanced efficacy along with lower liver toxicity as a result of lower lipid levels in the liver . the present invention employs low molecular weight cationic lipids comprising at least one short lipid chain to enhance the efficiency and tolerability of in vivo delivery of sirna .