Metal atom reactions with fluorocarbons. VI. Complexes of halogenated benzenes with vanadium(0) and chromium(0). Effects of strongly electron-withdrawing substituents, particularly trifluoromethyl groups

Early Transition Metals, Metal Halides, Metal Oxides, and Metal Sulfides Groups IIIB–VIIB)

“…A series of new bis(arene)vanadium(0) complexes have also been prepared by metal atom methods. 76 Resistive heating of V in W boats was employed where the V was held just at its softening point during vaporization. A variety of new F-and CF 3 -substituted derivatives were readily synthesized.…”

“…89 However, a few electron-demanding substituents can be tolerated, such as with C 6 H 4 F 2 or C 6 H 4 (CF 3 ) 2 . 76 Actually, the presence of one or two (but not more) F or CF 3 allows easier isolation of the complexes because their air stability becomes much greater and yet they still have good thermal stability. There is apparently a delicate balance; whereas more electron-rich arenes yield more strongly bonded complexes, they are in turn more readily oxidized.…”

“…There is apparently a delicate balance; whereas more electron-rich arenes yield more strongly bonded complexes, they are in turn more readily oxidized. 76 Indeed, electrochemical studies on a series of variously substituted bis (arene) Cr (0) complexes showed remarkably large variations in £ 1/2 [(Ar) 2 Cr(0) -• Ar 2 Cr + ], ranging from -0.2 volts for (C 6 H 5 OCH 3 ) 2 Cr to +1.2 volts for [(CF 3 ) 2 C 6 H 4 ] 2 Cr. [98][99][100] Calculations in conjunction with Hammett substituent cor relations indicated that the bonding in these systems is greatly affected by substituents because the σ-framework of the arene ring is greatly involved as well as is the π-framework in the M-ring bond.…”

Magnetic inequivalency, electron paramagnetic resonance spectroscopy, and electronic structure of the matrix-isolated (η6-C6H3F3)V half-sandwich

“…13 This was accomplished by computing the total hyperfine tensors of the 14 N 17 O 2 radical by ab initio multireference single and double excitation configuration interaction ͑MRSD-CI͒ techniques. From these tensors, the resonance field positions of the two spatially equivalent 17 O atoms were shown to be different. The computed and experimental differences in resonance field positions of the two 17 O atoms were compared and found to be in excellent agreement.…”

“…From these tensors, the resonance field positions of the two spatially equivalent 17 O atoms were shown to be different. The computed and experimental differences in resonance field positions of the two 17 O atoms were compared and found to be in excellent agreement. 13 a͒ Author to whom correspondence should be addressed; electronic mail: mattar@unb.ca The 17 O enriched NO 2 radical was chosen since there already exists EPR single-crystal data where the spectral linewidths are narrow and where the 17 O hyperfine resonances are completely resolved.…”