Syntheses, x-ray crystal structures, and ligand substitution kinetics of the carbon-bonded chromium(III) complexes trans-[CrR(acac)2(L)] (R = CH2Cl, CHCl2; L = H2O, CH3OH, pyridine)

Abstract

0 ) 04]•2 20 (b), and Figure 2, showing powder diffractograms of H[SnCl(0H)As04]-2H20 (a) and H[SnCl(0H)P04]-2H20 (2 pages).Ordering information is given on any current masthead page.

Unveiling the Takai Olefination Reagent via Tris(tert-butoxy)siloxy Variants

“…The difference in bond lengths in 5b is much more defined, where Cr1 is the likely trivalent species with overall shorter bond lengths. The Cr2−C1 bond lengths in 5a (2.05(1) Å) and 5b (2.046(2) Å) are similar to the bridging methylidene in 3, but are shorter than those in [Cr(acac) 2 (CHCl 2 )(py)] (2.13(1)/2.129(8) Å), 32,33 representing the only other dihalido-methanide chromium complex structurally characterized. In fact, [Ti(Cp)(acac)(μ 3 -S) 2 Ir 2 I-(CHI 2 )(CO) 4 ] seems to be the only other complex containing a di-iodo-methanide ligand.…”

Nucleophilicity of Ligated S22-Ions. Conversion of Organic Chlorides into Organosulfur Compounds incis-[(MCp*)2(μ-CH2)2(μ-S2R)]+(M = Rh, Ir)

“…It is worthwhile to discuss the reactivity of S 2 coordinated to Rh 2 or Ir 2 bimetallic units. As mentioned in the Introduction, activation of organic chlorides reported in the literature involves oxidative addition of chlorocarbons at the metal centers of complexes, before their transfer to organic molecules or their funcionalization in possible catalytic processes. ,− Activation of C−Cl bonds requires electron-rich centers, and thus compounds 1 and 2, having electron-rich centers, are able to activate C−Cl bonds of organic chlorides such as chlorotoluenes or carbon tetrachloride. The activation occurs at the electron-rich sulfur donor atoms, leading to formation of S-benzylated 4 , S,S-bridged thiobenzoate complexes 3 and 5 − 7 , or thioformate complex 8 .…”

“…Chlorinated organic compounds, such as chloroform, dichloromethane, carbon tetrachloride, and 1,1,1-trichloroethane, used in chemical laboratories, industries, electrical appliances, etc., are toxic, and some of them pose health hazards . The activation of carbon−chlorine bonds using chemical, microbial, or thermal methods, for converting organic halides into either less toxic or industrially useful materials, is an interesting area of research activity. − Very electron rich centers are required to produce rupture of the strong C−Cl bonds, such as those of CH 2 Cl 2 or CHCl 3 , , and the oxidative addition of chlorocarbons to metal complexes is the initial step for their activation either by further transfer to organic molecules or by their functionalization in possible catayltic processes . Among various metals, rhodium and iridium complexes have shown good reactivity toward chloroalkanes, for oxidative-addition reactions at their metal centers. − ,− …”

“…Thiolate anions S n 2- ( n = 1, 2, 3) can convert alkyl chloride into dialkyl oligosulfane by activation of the C−Cl bonds . Several metallosulfur systems are reported to react with chlorinated hydrocarbons; however, there is no report on mono- or multi-C−Cl bond activation by the insertion to the S−S bond of the coordinated S 2 ligand. − The S 2 ligand coordinated to the metal dinuclear unit in parallel in dinuclear cis- [(MCp*) 2 (μ-CH 2 ) 2 (μ-S 2 )] (Scheme : 1 , Rh; 2 , Ir, Cp* = C 5 Me 5 ) has high nucleophilicity, as noted toward dioxygen, and could be useful in activating C−Cl bonds. − Thus, using compound 2 , we have explored the novel multibond activation of C−Cl (or C−Cl and C−H) bonds in (1,1,1-trichloromethyl)benzene (C 6 H 5 CCl 3 ), (1,1-dichloromethyl)benzene (C 6 H 5 CHCl 2 ), and mono-chloromethylbenzene (C 6 H 5 CH 2 Cl) . In this paper, we report reactions of compound 1 with C 6 H 5 CCl 3 and p -ClC 6 H 4 CCl 3 as well as those of compound 2 with p -Cl-C 6 H 4 CCl 3 and carbon tetrachloride.…”

Oxidative Addition Reactions of [RhI(Br)(Tpy*)] (Tpy* = 4‘-(4-tert-Butylphenyl)-2,2‘:6‘,2‘ ‘-terpyridine) with Alkyl Bromides

“…The reactivity of metal-containing complexes toward oxidative addition reactions with carbon−halogen bonds is highly dependent on the electron density of the metal center. − For example, breaking carbon−chloride σ-bonds is only possible when very electron rich centers are used. ,− Therefore, in comparison to alkyl iodides and bromides, oxidative addition reactions of the less reactive alkyl chlorides are scarcer . The design of complexes with electron-rich metal centers is based on the use of strongly electron-donating ligands.…”