Tetra(2-oxopyridinato)chloroditechnitium. A new compound with a technetium-technetium bond of order 3.5 and a remarkable vibronic absorption spectrum

Abstract

Die Reaktion von 2‐Hydroxypyridin mit Ammoniumoctachlorotechnetat liefert in beinahe qunatitativer Ausb. die Titelverbindung als unendliche Kette mit Chloridbrücken.

Preparation of Octabromoditechnetate(III,II), [Tc2Br8]3- and the Vibronic Structure of the δ → δ* Transition

“…For K 3 [TC 2 C1 8 ] • 2 H 2 0 the spin-and orbitally-allowed Ö -*• Ö* transition has been assigned in good agreement with SCF-X a -SW calculations to a band originating in the near infrared region at 5900 cm -1 [2]. The vibrational progression on this transition is better resolved in the Cs-salt [3] and in the tetra(2-oxopyridinato)chloroditechnetate TC 2 (OC 5 H 4 N) 4 C1 [4]. The complicated vibronic structure of the latter compound has been assigned using polarized crystal spectra [4] 4 ] dissolved in tetrahydrofuran are mixed dropwise with 1400 mg (5.44 mmol) (TBA) [BH 4 ] in 50 ml tetrahydrofuran forming a brown reaction mixture.…”

“…The vibrational progression on this transition is better resolved in the Cs-salt [3] and in the tetra(2-oxopyridinato)chloroditechnetate TC 2 (OC 5 H 4 N) 4 C1 [4]. The complicated vibronic structure of the latter compound has been assigned using polarized crystal spectra [4] 4 ] dissolved in tetrahydrofuran are mixed dropwise with 1400 mg (5.44 mmol) (TBA) [BH 4 ] in 50 ml tetrahydrofuran forming a brown reaction mixture. To this diethylether is dropped until the entire brown intermediate is precipitated and the supernatant is colourless or transparent slightly yellow.…”

Physical, Spectroscopic and Theoretical Results

“…In Tc 2 (hp) 4 Cl (hp = anion of 2-hydroxypyridine the * type transition has a more complex plethora of vibrational components than in any other case. 221 Fortunately, this compound forms tetragonal crystals, with the molecules all parallel to the c-axis, and the polarized spectra were therefore cleanly accessible. It would probably have been impossible to separate the many components had the molecules not been entirely parallel to one another.…”

Difluorotetrakis(2‐oxypyridine)dirhenium(III) – Preparation, Crystallographic Structure, and Electrochemical Properties

“…The metal–metal bond chemistry of group 6–8 transition metal complexes containing pyridine derivatives is well developed. Quadruply bonded complexes with pyridine‐type ligands (Scheme ) usually exhibit the stoichiometry M 2 L 4 , M 2 L 4 X or M 2 L 2 X 2 , ( M = Cr, Mo, W, Tc, Re, Os, Ru) [HL = 2‐hydroxypyridine (2‐HOpy), 2‐methyl‐6‐hydroxypyridine (Hmhp), 2,4‐dimethyl‐6‐hydroxypyridine (Hdmhp), 6‐chloro‐2‐hydroxypyridine (chp)]. Cotton and Gage first reported Re 2 (2‐Opy) 4 Cl 2 , which was obtained from the reaction ( n Bu 4 N) 2 [Re 2 X 8 ] with molten 2‐hydroxypyridine in an inert atmosphere.…”