155145-72-5Relevant academic research and scientific papers
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.
