53749-04-5Relevant academic research and scientific papers
Technetium tetrachloride as A precursor for small technetium(IV) complexes
Hagenbach, Adelheid,Yegen, Eda,Abram, Ulrich
, p. 7331 - 7338 (2008/10/09)
Polymeric technetium tetrachloride reacts with monodentate donor ligands such as THF, acetonitrile, DMSO, thioxane (1-oxa-4-thiacyclohexane), PMe 2Ph, PPh3, OPPh3, or OH2 via cleavage of the polymeric network and the formation of [TcCl4(L) 2] complexes. The configuration of the products is dependent on the donor atoms such that trans coordination is established with 'soft' donor atoms such as sulfur or phosphorus, while cis-[TcCl4(L)2] complexes are formed with the 'harder' donors oxygen or nitrogen. The ambivalent thioxane binds to technetium via the sulfur atom. The trans products are air stable and resistant to hydrolysis. The cis complexes, however, undergo stepwise hydrolysis, during which complexes of the composition [Cl3(L) 2TcOTc(L)2Cl3] (L = CH3CN, DMSO, or OH2) are formed. They are the first representatives of a new class of technetium(IV) complexes with a bridging oxo ligand. The Tc-O bond lengths in these bridges are between 1.803(1) and 1.823(2) A.
Metal-metal multiply bonded complexes of technetium. 1. Synthesis and structural characterization of phosphine complexes that contain a Tc-Tc multiple bond
Burns, Carol J.,Burrell, Anthony K.,Albert Cotton,Haefner, Steven C.,Sattelberger, Alfred P.
, p. 2257 - 2264 (2008/10/08)
A series of triply metal-metal bonded ditechnetium(II) phosphine complexes with the general formula Tc2Cl4(PR3)4 (PR3 = PEt3, PPrn3, PMePh2, PMe2Ph) have been prepared from mononuclear Tc(IV) precursors and fully characterized. Two-electron reduction of the Tc(IV) bis(phosphine) complexes TcCl4(PR3)2 (PR3 = PEt3, PPrn3, PMePh2, PMe2Ph) with finely divided zinc in aromatic solvents or tetrahydrofuran results in the formation of the corresponding electron-rich triply bonded compounds Tc2Cl4(PR3)4 in high yield. These are the first phosphine complexes of technetium that possess a metal-metal bond. The solid-state structures of the PEt3, PMe2Ph, and PMePh2 derivatives have been investigated by X-ray crystallography and are described in detail. The crystallographic parameters for these compounds are as follows: Tc2Cl4(PEt3)4 (1), I43m with a = 12.3261(9) ?, V = 1872.7(2) ?3, and Z = 2; Tc2Cl4(PMe2Ph)4 (3), C2/c with a = 17.613(5) ?, b = 9.957(5) ?, c = 23.861(6) ?, β = 117.19(2)°, V = 3722 (2) ?3, and Z = 4; Tc2Cl4(PMePh2)4·C 6H6 (4·C6H6), P21/c with a = 22.910(2) ?, b = 12.286(2) ?, c = 21.550(2) ?, β = 115.867(6)°, V = 5458(1) ?3, and Z = 4. Similar to the analogous dirhenium(II) complexes, the molecules adopt an eclipsed M2L3 conformation with approximate D2d symmetry. The Tc-Tc bond lengths are 2.133(3), 2.127(1), and 2.1384(5) ? for Tc2Cl4(PEt3)4, Tc2Cl4(PMe2Ph)4, and Tc2Cl4(PMePh2)4, respectively. Structural and spectroscopic evidence indicates that these dimers contain an electron-rich Tc-Tc triple bond with a σ2π4δ2δ*2 ground-state electronic configuration. Electrochemical studies reveal that each compound undergoes two reversible one-electron oxidation processes, which presumably produce the corresponding Tc25+ and Tc26+ dinuclear species. 1H NMR, 31P{1H} NMR, and UV-vis spectroscopic data are presented for each compound.
