IUPAC Name: Magnesium ; Methanolate ; Methyl carbonate
Following is the structure of Methoxymagnesium-methyl carbonate (CAS NO.4861-79-4):
                
Empirical Formula: C₃H₆MgO₄
Molecular Weight: 130.3823 g/mol
EINECS: 225-466-4
Flash Point: 54.9 °C
Density: 1.103 g/mL at 25 °C
Enthalpy of Vaporization: 39.43 kJ/mol
Boiling Point: 119.1 °C at 760 mmHg
Vapour Pressure: 10.3 mmHg at 25 °C
Appearance of Methoxymagnesium-methyl carbonate (CAS NO.4861-79-4): clear slightly yellow solution
Canonical SMILES: C[O-].COC(=O)[O-].[Mg+2]
InChI: InChI=1S/C2H4O3.CH3O.Mg/c1-5-2(3)4;1-2;/h1H3,(H,3,4);1H3;/q;-1;+2/p-1
InChIKey: PNVKCUSCADAAMP-UHFFFAOYSA-M

 Methoxymagnesium-methyl carbonate (CAS NO.4861-79-4) hasn't been listed as a carcinogen by ACGIH, IARC, NTP, or CA Prop 65.. And the toxicological properties have not been fully investigated. You can see actual entry in RTECS for complete information.

Mutation data reported. When heated to decomposition, Methoxymagnesium-methyl carbonate (CAS NO.4861-79-4) emits toxic vapors of Mg.
Hazard Codes: T,F
Risk Statements: 45-20/21/22-36/37/38-23/24/25-11
R45:May cause cancer. 
R20/21/22:Harmful by inhalation, in contact with skin and if swallowed. 
R36/37/38:Irritating to eyes, respiratory system and skin. 
R23/24/25:Toxic by inhalation, in contact with skin and if swallowed. 
R11:Highly flammable.
Safety Statements: 53-26-27-36/37/39-45-38-16 
S53:Avoid exposure - obtain special instructions before use. 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection. 
S45:In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 
S38:In case of insufficient ventilation, wear suitable respiratory equipment. 
S16:Keep away from sources of ignition.
RIDADR: UN 1993 3/PG 3
F: 3-10-21
TSCA: Yes

 Methoxymagnesium-methyl carbonate , its cas register number is 4861-79-4. It also can be called Magnesium, methoxy(monomethyl carbonato-kappaO')- . Methoxymagnesium-methyl carbonate (CAS NO.4861-79-4) is stable under normal temperatures and pressures. It should avoid the condition of strong oxidants. And The incompatibilities with other materials is not available. Its hazardous decomposition products are Irritating and toxic fumes and gases. It should be stored in a cool, dry place. And keep container closed when not in use.