Kristall‐ und Molekülstruktur von Hydridobis‐[1,2‐bisdiphenylphosphanoethan]distickstofftechnetium(I)

Abstract

Die Kristall‐ und Molekülstruktur der im Titel genannten Verbindung HTcN2 (diphos)2 [diphos = (C6H5)2PCH2CH2P(C6H5)2] wurde mittels Röntgenstruktur‐ und 1H‐NMR‐Spektroskopie ermittelt. Die Kristalle sind monoklin mit a = 11,090(3), b = 24,550(5), c = 16,379(4) Å, β = 96,02(2)°, Raumgruppe P21/n. Das Technetiumatom ist oktaedrisch koordiniert, der Hydrid‐Wasserstoff befindet sich zum Distickstoff‐Liganden in trans‐Stellung. Der Bindungsabstand TcN beträgt 2,05(1) Å, der Tc‐H‐Abstand 1,7 (1) Å. Bemerkenswert kürzer ist der Abstand TcP (2,359(7) Å) im Vergleich zu Komplexen mit einzähnigen Phosphanliganden. Im 1H‐NMR‐Spektrum tritt bei δ = −10,08 ppm ein Signal für den Hydridwasserstoff auf.

Molecular and crystal structure of a mixed-phosphine ligand Tc(II) complex, Tc(PMe2Ph)2(DMPE)Cl2

“…The angles around the Tc atom are close to 90' and 1 80°, but there are some distortions caused by the presence of the bidentate ligand. The chelate angle P(1)-Tc-P (2) is only 80.1(1)", as was observed in other Tc-bidentate phosphine complexes (14)(15)(16)(17)(18)(19)(20) change the radius of the Tc atom, probably because it is paired in the low energy, t,, orbital. But the addition of a fifth electron (Tc(I1) has a d5 configuration) in the lower energy orbitals (t,, in an octahedral field with only one unpaired electron) seems to increase the Tc-Cl bond distances significantly, as expected.…”

Technetium Hydrides Revisited: Syntheses, Structures, and Reactions of [TcH3(PPh3)4] and [TcH(CO)3(PPh3)2]

“…Thus, we can compare the data obtained for the hydride 1 exclusively with the limited number of X-ray structure determinations on technetium hydrides. Only for two of them, the position of terminal hydrido ligands could be resolved experimentally, namely for [TcH­(N 2 )­(dppe) 2 ] with a Tc–H bond length of 1.7(1) Å and for [TcH 4 (PPh 2 Me) 4 ]­(BF 4 ) with Tc–H distances of 1.87 Å. , The H–H distances in [TcH 3 (PPh 3 ) 4 ] are between 2.44 and 2.64 Å and indicate the presence of classical hydrido ligands.…”

“…In contrast to the coordination chemistry of its higher congener rhenium, where many hydrido complexes are known and play an important role in a number of catalytic processes, − reports about compounds with technetium–hydrogen bonds are scarce. − Only some of them have been characterized unambiguously, e.g., by single crystal X-ray crystallography. This includes mononuclear compounds such as [TcH­(N 2 )­(dppe) 2 ], [TcH­{η 2 - N , S -HNC­(NH 2 )­S}­(PMe 3 ) 4 ]­(PF 6 ), or [Tc­(H 2 )­Cl­(dppe) 2 ], the binuclear compound [Tc 2 -μ-H­(μ- C , N -C 5 H 4 N)­(py) 2 (CO) 6 ], but also the trinuclear clusters [Tc 3 -μ-H 3 (CO) 12 ] , and [Tc 3 H­(CO) 14 ] or some borohydride compounds. , The structure of the iconic K 2 [TcH 9 ] was determined by comparison of its powder data with those of the rhenium analogue . Some of the compounds are shown in Chart .…”

“…It is nearly insoluble and only short-term-stable in KOH solutions at low temperatures . Although several hydrido and dihydrogen complexes can be derived from the 16-electron dppe complex [TcCl­(dppe) 2 ], their formation is exclusively limited to this bisphosphine ligand system. ,, …”

The hydride route to the preparation of dinitrogen complexes

“…84 It is worth noting that the technetium dinitrogen complex, (dppe) 2 TcH(N 2 ), can be isolated, although not via a hydride route as the required (dppe) 2 Tc{H} 3 species is unknown. 85 The homologous rhenium-hydrido species, (dppe) 2 ReH 3 (33), containing three hydrido ligands and two dppe chelates in a pentagonal bipyramidal coordination environment, 64 is thermally inert with respect to reductive elimination of H 2 . 86 Due to low quantum yields, photochemical elimination of dihydrogen can only be achieved via prolonged irradiation with UV light over a period of seven to ten days (Scheme 7).…”