Synthesis and characterization of polynuclear chromium(III) alkyls. Crystal structure of a paramagnetic .mu.3-methylidyne complex with short nonbonded chromium-chromium contacts

Ethylene polymerization by the chromium catalysts based on bidentate [O, PO] or [S, P] ligands

“…The two bridging groups are located at the position trans to the oxygen atoms of the phenoxy‐phosphinoyl ligands and the chlorine atoms occupies a position trans to the thf molecules. The nonbonded Cr ··· Cr distance (3.546 Å) is in the range found in a number of other chloride‐bridged chromium complexes (3.64–3.23 Å) 23. Different from A , complexes B and C with bulky ortho ‐phenoxy substituents show octahedral coordination at the chromium center with a single bidentate [O, PO] ligand and two cis ‐coordinated thf molecules, as shown in Figure 3 (O(1)CrO(2) 91.70°; Cl(1)CrCl(2) 95.35°) and Figure 4 (O(1)CrO(2) 92.22°; Cl(1)CrCl(2) 94.66°).…”

Reactivity ofμ3-Alkylidyne Groups on an Organotitanium Oxide: Insertion of Isocyanides and Carbon Monoxide into the Complexes [{TiCp*(μ-O)}3(μ3-CR)] (R=H, Me)

“…The 13 C chemical shifts for the alkylidyne carbons CH [d 78.5 (6, 7)] and CMe [d 92.3 (8,9)] and the values of direct carbon ± proton [J 174 Hz (6, 7)] and carbon ± carbon [J 44 Hz (6)] coupling constants are typical of organic olefin fragments. These data are in agreement with the insertion of isocyanide molecules into Ti ± C(alkylidyne) bonds and the loss of coordination to any metal atom for the a-carbon of the ethylidyne group as found in the X-ray study of 9.…”

“…[4,5] The chemistry of the m 3 -alkylidynetrimetal clusters has been extensively explored. [3a, 6] Meanwhile, to our knowledge, the [{CrCp(m-Cl)} 3 (m 3 -CH)] [7] (Cp h 5 -C 5 H 5 ), [{TiCp*(m-O)} 3 (m 3 -CR)] [1] and [{TiCp*} 4 (m 3 -CH) 4 ] [8] complexes are the only reported examples of m 3 -alkylidyne units supported on trinuclear cores without metal ± metal bonds, and their reactivity is as yet practically unknown. [9] The facile and high-yield synthesis of these [{TiCp* (m-O)} 3 (m 3 À CR)] complexes provide us with the opportunity to investigate the chemistry of these d 0 m 3 -alkylidyne compounds.…”

Beyond Takai's Olefination Reagent: Persistent Dehalogenation Emerges in a Chromium(III)‐μ3‐Methylidyne Complex

“…While molecules [X3CrºCH] (X = F, Cl) have been observed in an argon matrix (8 K), [5] heteroatom-substituted carbyne derivatives such as [(C5Me5)Cr(ºCNiPr2)(CNtBu)3][PF6]2 [6] and the trimetallic cluster [Cp3Cr3(μ2-Cl)3(μ3-CH)] (A) [7] display crystalline compounds. [7] Purple trivalent A has remained the only structurally characterized methylidyne complex of chromium, [7,8] On the other hand the M3(μ3-CH) entity exhibits a common structural motif detected throughout d-transition metal chemistry (Ti, Co, Fe, Ru, Re and Os). [9] Prominent examples of the μ3alkylidyne compound class are tricobalt nonacarbonyl clusters, first mentioned 1970 by Seyferth et al [10] Methylidyne complexes structurally related/ isostructural to A comprise [{Cp*Ti(μ-O)}3(μ3-CH)] [11] and [Cp*3Mo3(µ-O)2(µ-CH2)(µ3-CH)] [12] the reactivity of which has been investigated as well.…”