DOUBLE FLUORIDES OF TANTALUM.¹

Abstract

I 140 CLAREKCE W. BALKE.Guanidine acetate, used instead of the thiocyanate, gave the same condensation-product.An attempt was made to prepare the naphttetrazine by direct fusion of succinylosuccinic ester and guanidine acetate, in the same way that the diimine was made from succinylosuccinic ester and ammonium acetate, but no condensation occurred.Finally, a solution of free guanidine was prepared from the carbonate and condensed with succinylosuccinic ester, but this variation showed no adrantage over the use of a guanidine salt and sodium ethylate either in the yield or purity of the product.

Formation and Characterization of the Oxygen-Rich Hafnium Dioxygen Complexes: OHf(η2-O2)(η2-O3), Hf(η2-O2)3, and Hf(η2-O2)4

“…Great effort has been devoted to characterize the structures and reactivity of transition metal−dioxygen complexes, which are important reactive intermediates in most oxidation processes. − On the basis of the O−O bond distance and O−O stretching vibrational frequency, metal−dioxygen complexes have been defined as superoxo or peroxo complexes − reports of superoxo complexes are rare . A series of gas-phase investigations were limited to the neutral and ionic metal oxide clusters with different metal/O ratios. − Gas-phase kinetic 19-22 as well as matrix isolation spectroscopic studies 23-27 indicate that early transition metal atoms react with dioxygen directly to form metal oxides without a significant activation barrier.…”

“…A series of gas-phase investigations were limited to the neutral and ionic metal oxide clusters with different metal/O ratios. − Gas-phase kinetic 19-22 as well as matrix isolation spectroscopic studies 23-27 indicate that early transition metal atoms react with dioxygen directly to form metal oxides without a significant activation barrier. The binding of early transition metal complexes with dioxygen results in the formation of a number of heteroleptic transition metal peroxo complexes, which provide direct information about their structures and mechanisms of dioxygen activation. − Since the first preparation of M 3 [Ta(O 2 ) 4 ] (M = Na or K), a large number of homoleptic tetraperoxometalate compounds of group V and VI metals have also been synthesized and characterized. − These compounds show the ability to release oxygen in active form, either by chemical means or under irradiation, and act in oxidations of inorganic and organic substrates.…”

Ammonium tantalum oxide fluorides: new features of dynamic disorder

“…As described in the literature, under these conditions two fluoride salts of tantalum can form: (NH 4 ) 3 TaOF 6 and (NH 4 ) 3 TaF 8 . Balke (1905) reported obtaining octafluorotantalate, (NH 4 ) 3 TaF 8 , relying only on the content of metal in the form of its pentoxide. Joly (1875) described an ammonium oxide fluoride of tantalum of the composition (NH 4 ) 3 TaOF 6 .…”