Syntheses and characterization of unique organometallic nickel(III) aryl species. ESR and electrochemical studies and the x-ray molecular study of square-pyramidal [Ni{C6H3(CH2NMe2)2-o,o'}I2]

Abstract

in III, where it can be seen that because of the large phenyl substituents it is understandably disfavored here. IllIn conclusion, then, the introduction of the "stiffened backbone" in dppee, as contrasted with the flexible backbone in dppe, leads to certain changes in the conformational characteristics of these molecules. These conformational changes then have consequences with respect to the way in which the molecules are assembled in the complete crystal structure.Acknowledgment. Support from the National Science Foundation (Grant No. CHE85-14588 to F.A.C. and Grant No. 85-06702 to R.A.W.) is gratefully acknowledged.Registry No. a-Re2Cl4(dppee)2-«-PrOH, 114720-22-8; /3-Re2Cl4-(dppee)2, 110329-68-5; a-Re2Cl4(dppe)2, 114720-23-9; (n-Bu4N)2Re2Cls, 14023-10-0; [ReCl2(dppe)2]Cl, 15628-22-5; (zi-Bu4N)2Re2Br8, 14049-60-6; a-Re2Br4(dppe)2, 114720-24-0; a-[Re2Cl4(dppee)2]PF6, 114720-26-2; (Cp2Fe)PF6, 11077-24-0; a-[Re2Cl4(dppp)2]PF6, 114720-28-4; a-Re2Cl4(dppp)2, 86436-61-5; Re, 7440-15-5; a-Re2Cl4(dppee)2, 1 10329-67-4. Supplementary Material Available: Full tables of bond distances and bond angles and tables of anisotropic displacement parameters for a-Re2Cl4(dppee)2.«-PrOH and 0-Re2Cl4(dppee)2 and a table of torsional angles for the ß isomer (14 pages); listings of observed and calculated structure factors for both compounds (45 pages). Ordering information is given on any current masthead page.

Changes in redox potential of a nickel-pincer complex bearing reactive secondary thioamide units: Changes caused by deprotonation/protonation reactions on addition of NEt3 and DBU

“…1, [Ni(SCS)Br] shows a reversible redox wave at E 1/2 =+0.156 V (vs. Fc + / Fc), which is assigned to an Ni(II)/Ni(III) redox process. The E 1/2(Ni(II)/Ni(III)) is comparable to that of a previously reported Ni-pincer complex, [Ni(NCN)Br] (NCN = C 6 H 3 (CH 2 NMe 2 ) 2 -o,o′; E 1/2(Ni(II)/Ni(III)) = + 0.15 V (vs. SCE)) [5]. The strong electron-donating ability of the pincer ligand seems to give such a lower Ni(II)/Ni(III) potential than that of usual Ni(II) complexes; for instance, E 1/2(Ni(II)/Ni(III)) of [Ni(bpy) 3 ] 2+ (bpy = 2,2′-bipyridyl) is observed at 1.66 V vs. SCE (or 1.13 V vs. Fc + /Fc) [6].…”

Homoleptic Organoderivatives of High‐Valent Nickel(III)

“…[36] However, very few compounds containing Ni iii À C s bonds have been isolated and characterized to date. [37] Most of them take advantage of the chelate or "pincer" effect, since the C-donor atom belongs to a polydentate ligand that helps to enhance the stability of the corresponding metal complex. Moreover, all of them are five-or six-coordinate species, and are therefore electronically and coordinatively more saturated than our four-coordinate, 15-electron derivatives 3 and 4.…”

Cyclic voltammetric studies of copper complexes catalyzing atom transfer radical polymerization

“…Correlation between ATRP kinetics and the redox potentials of the CuBr complexes. [18] and CH 2 Cl 2 , [17] copper complexes with linear tetramine ligands (Cu(N 4 Me 6 ), Cu(N 4 H 2 Me 4 )) [27] and other copper complexes in aqueous solution. [26] The values of E 1/2 of the nickel complexes are calculated based on published data vs. Fc/Fc + (0.55 V vs. NHE).…”

“…Previously, van Koten et al [17,18] studied the electrochemistry of arylnickel(II) complexes. They found that the redox potential of the complex was very sensitive to the para-substitution of the ligands and the counterion of the complex, which in turn strongly affected the catalytic behavior of the nickel complexes in ATRA reactions.…”