In diethylzinc (Zn(C2H5)2), the oxidation state of zinc is +2. This can be determined by considering the electronegativity of the atoms involved. Carbon is more electronegative than zinc, so the electrons in the C-Zn bonds are pulled towards the carbon atoms. This creates a partial negative charge on the carbon atoms and a partial positive charge on the zinc atom. The oxidation state of zinc is therefore +2.