Chromium phenyl complex

An organometallic dioxygen adduct of an even more fleeting kind was observed in the reaction of the divalent chromium phenyl complex Tp > Cr-... 

Other miscellaneous imines that underwent photoreaction with chromium alkoxycarbenes include iminodithiocarbonates [33],the mono-N-phenylimine of benzil and the bis-JV-phenyl imine of acetoin [20]. By preparing the chromium carbene complex from 13CO-labeled chromium hexacarbonyl, /J-lactams with two adjacent 13C labels were synthesized [34]. 

The substituent effects on the alkene were investigated in the reaction of enyne 12 and chromium carbene complex 2c [8]. In the reaction of enyne -12a having a phenyl group on the alkene with Fischer chromium carbene complex 2c, metathesis product 13a was obtained as a main product along with cyclopropane 14 and cyclobutanone 15 (Eq.4). The reaction of Z-12a with 2c gave only... 

The 774-vinylketene complex (85) could be oxidatively decomplexed with Ce(IV) to afford the lactone (87). Although no reaction was observed with methanol (unlike a postulated chromium analogue16,18 26), treatment with sodium methoxide produced the expected /3, y-unsaturated ester (88). Thermolysis of complex 85 afforded no trace of the naphthol that one would expect33 from a proposed chromium vinylketene complex with the same syn relationship between the phenyl group and the ketene moiety. Instead, only the furan (89.a) was seen. Indeed, upon exhaustive reaction of tricarbon-ylcobalt carbenes (84 and 90) with different alkynes, the furans (89.a-d) were isolated as the exclusive products in moderate to excellent yields. 

An interesting picture was revealed by Gouverd et al. (2006) as a result of comparison between the neutral chromium tricarbonyl complex of C,P-diaryl phosphaalkene [(CO)3Cr<—PhCH=PMes ] and its anion-radical [(CO)3Cr <— PhCH=PMes ] (Mes is 2,4,6-tris(tert-butyl)phenyl). According to the ESR and DFT data for the anion-radical, about 40% of the negative charge is localized on Cr(CO)3 moiety. This is understandable if one takes into account the known electron-acceptor... 

Some novel silicon-containing arene-chromium tricarbonyl complexes (IV-VII), derived from phenyl-substituted silacyclobutanes (118), 1,1-dimethylsilaindane (120) and alkynylarenes (45), have been prepared by essentially identical methods. It is worth mentioning here that the organosilicon complex (VI) is somewhat more thermally stable than the silicon-free 1,1-dimethylindane complex (120). 

Compounds containing chromium directly linked to a cyclosilanyl ring are not known so far. From hexacarbonylchromium and mono- or diphenylcyclopenta- and hexasilanes, however, the corresponding tricarbonylchromium r/ -phenyl complexes have recently been synthesized106 (Scheme 28). 

Mixed donor tridentate [NPS] ligated derivatives, chromium(III) complexes, 5, 370 Mixed iridium carbonyl dimers, preparation, 7, 289 Mixed isonitrile acetylides, liquid crystals, 12, 281 Mixed isonitrile phenyl complexes, liquid crystals, 12, 282 Mixed ligand triangular Pt carbonyl clusters, characteristics, 8, 411... 

A theoretical study of the chiral recognition of the bis(amino(phenyl)methanol) chromium(O) complexes and chiral discrimination of the dimers of amino(phenyl) methanol linked by HB has been carried out by means of a DFT method, the B3LYP/6-31+G. The results (Fig. 3.24) show that in the chromium complexes, the homochiral one is preferred over the heterochiral one, while the opposite... 

K. Zborowski et al., A theoretical study of chiral recognition in bis[amino (phenyl) methanol] chromium(O) complexes. Pol. J. Chem. 81, 621-629 (2007)... 

Besides alkyloxy carbene complexes, acyloxy carbene complexes have also been proven to be effective in the benzannulation reaction. For example, Yamashita and Ohishi have reported the synthesis of various naphthoquinones in yields of 47-71 % using acetyloxy phenyl chromium carbene complex and terminal alkynes with different alkyl chain lengths [29]. 

Chromium-salen complexes have been used for the reaction between styrene epoxide and scC02 in [C4Ciim][PF6], as illustrated in Scheme 9.15.1601 At low catalyst concentrations, 1-phenyl-1,2-ethanediol was detected as a by-product while at a catalyst loading of ca. 0.35 mol%, 100% selectivity was obtained. Recycling of the catalyst was possible, but the ionic liquid phase needed to be exhaustively purified with volatile organic solvents prior to its reuse. 

Although the n bond is used for coordination in all four compounds, the As—As separation (ca 2.36 A) points to retention of double-bond character. A diarsene carrying a Cp Fe(CO)2 substituent in addition to the well known tri(t-butyl)phenyl group has been isolated as a chromium pentacarbonyl complex, 20, from treatment of Cp Fe(CO)2 As(SiMe3)2 with tri(t-butyl)phenylarsenic dichloride and (cyclo-octene)Cr(CO)5. The compound, which is isostructural with the corresponding diphosphene and phospha-arsene, has an As—As separation of 2.259 A and As—Cr and As—Fe distances of 2.492 and 2.387 A, respectively. On the other hand, the As—As distance in [CpFe(CO)2]-(PhAs—AsPh)[(CO)2FeCp] is 2.456 A and the compound is probably best described as a tetrasubstituted diarsine, rather than a diarsene complex . 

An important question has yet to be answered are rr-complexed organometal systems capable of controlling the stereochemistry of 1,2 shifts The n-(arene) chromium tricarbonyl complexes of threo- and eryrfcro-3-phenyl-2-butyl mesylates, (900) and (901), and of e/7fhro-2-phenyl-3-pentyl mesylate (902) have been aceto-... 

But-2-enedinitrile, 2-nitropropene, phenyl vinyl sulfoxide, styrene and but-2-enal do not form 1-methoxy-l -phenylcyclopropanes with the corresponding chromium-carbene complex. " On the other hand, methyl vinyl ketone gave a formal 1,4-adduct, which, due to its instability, was further transformed under acidic conditions. ... 

---