The molecular structure of Methidathion (CAS NO.950-37-8):

IUPAC Name: 3-(Dimethoxyphosphinothioylsulfanylmethyl)-5-methoxy-1,3,4-thiadiazol-2-one 
Molecular Weight: 302.331301 g/mol
Molecular Formula: C₆H₁₁N₂O₄PS₃ 
Density: 1.6 g/cm³ 
Melting Point: 39-40 °C
Boiling Point: 347.7 °C at 760 mmHg 
Flash Point: 164.1 °C
Index of Refraction: 1.651
Molar Refractivity: 68.92 cm³
Molar Volume: 188.5 cm³
Surface Tension: 60.4 dyne/cm 
Enthalpy of Vaporization: 59.2 kJ/mol
Vapour Pressure: 5.28E-05 mmHg at 25 °C 
Storage Temp.: 0-6 °C
Water Solubility: 0.024 g/100 mL
XLogP3: 2.4
H-Bond Acceptor: 5
Rotatable Bond Count: 6
Exact Mass: 301.961855
MonoIsotopic Mass: 301.961855
Topological Polar Surface Area: 60.4
Heavy Atom Count: 16
Canonical SMILES: COC1=NN(C(=O)S1)CSP(=S)(OC)OC
InChI: InChI=1S/C6H11N2O4PS3/c1-10-5-7-8(6(9)16-5)4-15-13(14,11-2)12-3/h4H2,1-3H3
InChIKey: MEBQXILRKZHVCX-UHFFFAOYSA-N
EINECS: 213-449-4
Product Categories: INSECTICIDE; Endocrine Disruptors (Draft)Alphabetic; Alpha sort; Endocrine Disruptors (Draft)Pesticides&Metabolites; EPA; H-MAlphabetic; Insecticides; M; META - METHPesticides; Method Specific; Organophorous

 Methidathion (CAS NO.950-37-8) is an organophosphate insecticide. And it is used as a non-systemic insecticide.

EPA Extremely Hazardous Substances List.

Hazard Codes: T+; N
Risk Statements: 21-28-50/53 
R21:Harmful in contact with skin. 
R28:Very toxic if swallowed. 
R50/53:Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
Safety Statements: 22-28-36/37-45-60-61 
S22:Do not breathe dust. 
S28:After contact with skin, wash immediately with plenty of soap-suds. 
S36/37:Wear suitable protective clothing and gloves. 
S45:In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 
S60:This material and its container must be disposed of as hazardous waste. 
S61:Avoid release to the environment. Refer to special instructions / safety data sheets.
RIDADR: UN 2811
RTECS: TE2100000
HazardClass: 6.1(a)
PackingGroup: II
Poison by ingestion and skin contact. Moderately toxic by inhalation. Human mutation data reported. Human systemic effects: coma, lachrymation, miosis. A severe eye irritant. An insecticide. When heated to decomposition it emits very toxic fumes of NO_x, PO_x, and SO_x.

 Methidathion (CAS NO.950-37-8) is also named as (O,O-Dimethyl)-S-(-2-methoxy-delta(sup 2)-1,3,4-thiadiazolin-5-on-4-ylmethyl)dithiophosphate ; 3-Dimethoxyphosphinothioylthiomethyl-5-methoxy-1,3,4-thiadiazol-2(3H)-one ; AI3-27193 ; BRN 0619915 ; CCRIS 7085 ; Caswell No. 378B ; Ciba-Geigy GS 13005 ; DMTP (insecticide) ; Dithiophosphoric acid O,O'-dimethyl-S-((2-methoxy-1,3,4-thiadiazol-5(4H)-on-4-yl)methyl) ester ; O,O'-Dimethyl-S-((2-methoxy-1,3,4-thiadiazole-5(4H)-one-4-yl)methyl) dithiophosphate ; O,O-Dimethyl S-(2,3-dihydro-5-methoxy-2-oxo-1,3,4-thiadiazol-3-ylmethyl) phosphorodithioate ; Phosphorodithioic acid, O,O-dimethyl ester, S-ester with 4-(mercaptomethyl)-2-methoxy-delta(2)-1,3,4-thiadiazolin-5-one ; S-(2,3-Dihydro-5-methoxy-2-oxo-1,3,4-thiadiazol-3-methyl)dimethyl phosphorothiolothionate ; Somonil ; Supracid ; Supracide ; Supracide Ulvair ; Suprathion ; Ultracid ; Ultracid 40 ; Ultracid EC 40 ; Ultracide ; Ultracide Ulvair 250 . Methidathion (CAS NO.950-37-8) is colorless crystals. It is stable in neutral or weak acid solution. It can be hydrolyzed by alkali. Organophosphates, such as Methidathion, are susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides. Methidathion is poisonous to humans. Its toxic effects are by action on the nervous system. Container may explode in heat of fire. Fire and runoff from fire control water may produce irritating or poisonous gases.