Exceptional thermal stability and high volatility in mid to late first row transition metal complexes containing carbohydrazide ligands

Treatment of metal(II) halides (metal = Cu, Ni, Co, Fe, Mn, Cr) with the potassium salts of carbohydrazides L 1 –L 6 afforded Cu(L 1 ) 2 (75%), Cu(L 2 ) 2 (51%), Cu(L 3 ) 2 (23%), Co(L 1 ) 2 (57%), Cr(L 1 ) 2 (62%), Ni(L 1 ) 2 (76%), Ni(L 2 ) 2 (62%), Ni(L 3 ) 2 (62%), Ni(L 4 ) 2 (13%), Ni(L 5 ) 2 (11%), Ni(L 6 ) 2 (29%), [Fe(L 1 ) 2 ] 2 (28%), and [Mn(L 1 ) 2 ] 2 (12%) as crystalline solids, where L 1  = Me 2 NN C(tBu)O − , L 2  = Me 2 NN C(iPr)O − , L 3  = Me 2 NN C(Me)O − , L 4  = (CH 2 ) 5 NN C(tBu)O − , L 5  = (CH 2 ) 5 NN C(iPr)O − , and L 6  = (CH 2 ) 5 NN C(Me)O − . These complexes were characterized by spectral and analytical techniques, and by X-ray crystal structure determinations for Cu(L 1 ) 2 , Co(L 1 ) 2 , Cr(L 1 ) 2 , Ni(L 1 ) 2 , and [Fe(L 1 ) 2 ] 2 . Cu(L 1 ) 2 , Co(L 1 ) 2 , Cr(L 1 ) 2 , and Ni(L 1 ) 2 exist as square planar, monomeric complexes, whereas [Fe(L 1 ) 2 ] 2 is a dimer. A combination of sublimation studies, thermal decomposition temperature determinations, and thermogravimetric/differential thermal analysis demonstrate that the Cu, Co, and Ni complexes Cu(L 1 ) 2 , Cu(L 2 ) 2 , Co(L 1 ) 2 , Ni(L 1 ) 2 , and Ni(L 2 ) 2 have the lowest sublimation temperatures and highest decomposition temperatures among the series. Additionally, these compounds have higher volatilities and thermal stabilities than commonly used ALD and CVD precursors. Hence, these new complexes have excellent properties for application as ALD precursors to Cu, Co, and Ni metal films.