Reactivity of Transition Metal Gallylene Complexes Toward Substrates with Multiple Carbon-Element Bonds.

Reactivity of transition metal complexes containing the redox-active gallylene (dpp-bian)Ga ligand (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) toward isocyanide, isocyanate, isothiocyanate, and ketene substrates is described. The reaction of [(dpp-bian)GaCr(CO) 5 ] ( 1 ) with tBuNC results in a dative complex [(dpp-bian)Ga(CNtBu)Cr(CO) 5 ] ( 2 ), while compound [(dpp-bian)GaCr(CO) 5 ] 2 [Na(THF) 2 ] 2 ( 3 ) reacts with tBuNC to give the coordination polymer [(dpp-bian)GaCr(CO) 5 ][Na(CNtBu)(THF)] n ( 5 ). Treatment of [(dpp-bian)GaCr(CO) 5 ] 2 [Na(THF) 2 ] 2 with an excess of PhNCO results in trimerization of the latter and formation of complex [(dpp-bian)GaCr(CO) 5 ][Na(PhNCO) 3 (Et 2 O) (DME)] ( 4 ). [(dpp-bian)GaFeCp(CO) 2 ] ( 7 ) treated with Ph 2 CCO or PhNCS results in cycloaddition products [(dpp-bian)(Ph 2 CCO)GaFeCp(CO) 2 ] ( 8 ) and [(dpp-bian)(PhNCS)GaFeCp(CO) 2 ] ( 9 ). The formation of 2 and 9 was found to be reversible, which offers a means for facile regulation of transition metal center reactivity and cooperative substrate activation. New compounds were characterized by EPR ( 2 ), NMR ( 4 , 8 , and 9 ), and IR spectroscopy ( 2 , 4 , 5 , 8 , and 9 ). The molecular structures of 2 , 4 , 5 , 8 , and 9 were established by single-crystal X-ray diffraction analysis. Electronic structures of the compounds have been examined by DFT calculations.