Treatment of the hafnocene complex bearing a strongly activated, side-on bound dinitrogen ligand, [(eta(5)-C5Me4H)(2)Hf](2)(mu(2),eta(2),eta(2)-N-2), with two equivalents of methyl triflate yielded a mixture of products, one of which was identified as the triflato hafnocene methyl diazenide compound, (eta(5)-C5Me4H)(2)Hf(OTf)(N-2(CH3)), arising from methylation of one of the nitrogen atoms This reactivity contrasts with that of the zrconocene congener, [(eta(5)-C5Me4H)(2)Zr](2)(mu(2),eta(2),eta(2)-N-2), where methyl triflate addition yields a variety of products that lack new nitrogen-carbon bonds The methylated hafnocene product, (eta(5)-C5Me4H)(2)Hf(OTf)(N-2(CH3)) provides a platform for additional transformations for the functionalized dinitrogen core Treatment with additional methyl triflate results in a second nitrogen-carbon bond formation to yield a rare example of a triflato hafnocene hydrazonato complex. Loss of methane and formation of the hafnocene bis(triflate) accompany the transformation Isotopic labeling studies and other experiments are consistent with a pathway involving initial methylation of the unsubstituted nitrogen in the methyl diazenido ligand followed by deprotonation by a triflate anion.