Abstract: [Et2NH2][(4-MeC6H4O)2PS2](N,N-diethylammonium O,O′-di(4-methylphenyl)dithiophosphate,NOP) was synthesized and characterized by elemental analysis, IR, TG-DSC, and single crystal X-ray diffraction analysis. The thermal stability and corrosion inhibition were investigated. The crystallographic structure analysis reveals that the title compound crystallizes in monoclinic system, P 21/n space group, a=1.4241(3) nm， b=2.0087(4) nm， c=1.4366(3) nm， V=3.9599(15) nm3, Dc=1.286 Mg/m3， Z=8， F(000)=1.632， μ(MoKα)=0.360 mm-1,S=1.001,(Δ/σ)max=0.001, R1=0.077 6, wR2=0.174 9(I＞2σ(I)) .There are two independent subunits in the asymmetric structure unit of NOP, and infinite onedimensional chain structure is formed viaN-H…S hydrogen bonds between the subunits. The corrosion inhibition study showed that the NOP could effectively restrain corrosion of Q235 steel in H2SO4 solution. It was shown that the adsorption of NOP on the Q235 steel surface is consistent with the Langmuir adsorption isotherm, and the corrosion inhibition depends on both physical sorption and chemical sorptions. CCDC:813309

Key words: O,O&, prime, -dialkyldithiophosphate, crystal structure, thermal stability, corrosion inhibitor, adsorption