in solid matrix Irradiation (UV/VIS); photolysis at 313 nm at 12 K in CO/CH4 matrix, then photolysis with broadband light; not isolated, detected by IR;

With  NbCl3(CH3OCH2CH2OCH3) in  ethylene glycol dimethyl ether  under Ar; addn. of Cr-complex/DME (1-2 equiv) to Nb-compd./DME at room temp., mixt. stirred; addn. of satd. Na2CO3, extd. (ether, twice), combined organics dried (MgSO4), filtered, evapn. (vac.), flash chromy. (silica gel, light petroleum-diethyl ether (7/3));   

With  carbon monoxide; hydrogen; triethylamine; bis-triphenylphosphine-palladium(II) chloride in  toluene  High Pressure; stainless steel, Teflon-coated autoclave, PPh3 presence (catalytic system), 15 bar CO, 15 bar H2, 130°C, 20-70 h; at 1 bar CO/H2 yield 28percent; GLC; org. byproducts (non-coordinated) also formed;   

With  manganese(IV) oxide in  dichloromethane  under gentle conditions;;