Metal-Metal Multiply-Bonded Complexes of Technetium. 2. Preparation and Characterization of the Fully Solvated Ditechnetium Cation [Tc2(CH3CN)10]4+

Abstract

Acidification of TczCk(PR3)4 with HBF4.Et20 in a mixture of acetonitrile and methylene chloride results in the formation of the metal-metal triply-bonded solvated complex [Tc2(CH3CN)lo] [BF& (1) in 80% yield. This compound may also be prepared through reduction of [ B u~N ]~[ T c C~~] with either BusSnH or finely divided Zn followed by treatment with HBF40Et20, but in lower yields (approximately 50%). The quadruply bonded species Tc2Cls2-also reacts with HBF4.Et20 in a mixture of acetonitrile and diethyl ether under mild heating to produce small amounts of blue [TC~(CH~CN)I~][BF& (yield 14%). In addition to the formation of 1, yellow crystals that proved to be the mononuclear Tc (II1) species [ T c C~~( C H~C N )~] [ B F~] (2) were isolated in 34% yield from the reaction solution. The dinuclear cation [Tc2(CH3CN)1ol4+ was crystallized as tfie mixed salt [ T c~( C H~C N )~( C F~-S03)2](BF&CH3CN (laCH3CN) by addition of 8 equivs of Tl(CF3S03) to a CH3CN solution of 1 followed by slow diffusion of a mixture of Et20 and hexanes. Compound laCH3CN crystallized in the tetragonal space group P41212 with a = 12.181(2) A, c = 27.385(3) A, V = 4063(1) A3 and 2 = 4. The molecular structure of la entails a staggered M2L8 conformation with approximate D u symmetry. The two axial positions of the dinuclear cation are occupied by CF3SO3-anions. The BF4-anions occupy general positions within the unit cell. The T c q c bond distance is 2.122(1) A, consistent with a Tc-Tc multiple bond. Single crystal X-ray analysis of [ T c C~~( C H~C N )~] [ B F~] revealed a trans disposition of chloride ligands with approximate D4h symmetryo about the Tc atom. Crystal data for 2: orthorhombic space group Zbam, with a = 6.250(1) A, b = 12.189(2) A, c = 20.880(5) A, V = 1590.7(5) A3 and Z = 4. Nitrile complexes 1 and 2 have been fully characterized by a variety of physical and spectroscopic techniques including 'H NMR, UV-vis and IR spectroscopies and cyclic voltammetry.

The Reaction of Cs2[Tc(NO)F5] with BF3 in Acetonitrile: Formation and Structure of [{Tc(NO)(CH3CN)4}2(μ‐F)](BF4)3

“…The bridging Tc–F bonds in [{Tc I (NO)(CH 3 CN) 4 } 2 F] 3+ are longer than the terminal ones in Cs 2 [Tc(NO)F 5 ], but very similar to the values in the technetium(VII) oxyfluorides mentioned above. The Tc–N(acetonitrile) bonds are unexceptional and in the same magnitude like those in the metal–metal multiply‐bonded ditechnetium cation [Tc 2 (CH 3 CN) 10 ] 4+ and its derivatives …”

C‐terminal Tensin‐like (CTEN) is an oncogene which alters cell motility possibly through repression of E‐cadherin in colorectal cancer

“…is reduced with respect to the free RCN by 43 and 15 cm −1 , for R=Me, Ph, respectively 43. This is not the situation for either [Ru III (NH 3 ) 5 (NCR)] 3+ 43 or for [M II 2 (NCMe) 10 ] 4+ complexes with M II =Mo II , Tc II , Rh II , where the $\tilde \nu $ CN band shifts to higher wavenumber with respect to free MeCN (M=Mo,46 Tc,47 Rh48). Therefore, shifting $\tilde \nu $ CN to higher values, while the general trend, may not always occur, particularly if backbonding is significant.…”

Tetracyanoethylene (TCNE): The Characteristic Geometries and Vibrational Absorptions of Its Numerous Structures

“…3+ [43] or for [M II , Rh II , where the ñ CN band shifts to higher wavenumber with respect to free MeCN (M = Mo, [46] Tc, [47] Rh [48] ). Therefore, shifting ñ CN to higher values, while the general trend, may not always occur, particularly if backbonding is significant.…”