A new scheme to realize simultaneous negative permittivity and permeability in a three-level closed Λ system with incoherent pumping via spontaneously generated coherence has been presented. We have shown that the negative refractive index can be realized in a heteronuclear molecule such as LiH. The negative refractive index can be achieved in a band of frequency range. The position and the band of the frequency region of negative refraction can be manipulated by controlling the incoherent pump rate. We achieve a figure of merit (FOM) = |Re(n)/Im(n)| = 1.797 for the LiH molecule.