hydroquinone; (CO)5W[CNC6H4NO2] in toluene byproducts: (Bu3Sn)2; alkyne and catalyst with hydroquinone dissolved in abs. toluene, heated for 15 min at 60°C, Bu3SnH added, heated for 12 h at 60°C; solv. removed, chromy over silica gel with pure hexane, then hexane/ethyl acetate/1percent triethylamine, 98-90percent hexane;