Nonclassical Metal Carbonyls

Lupinetti, Anthony J.; Strauss, Steven H.; Frenking, Gernot

doi:10.1002/9780470166512.ch1

Cited by 163 publications

(185 citation statements)

References 326 publications

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“…2B). Finally, the calculated and observed blue-shifted values are consistent with the strongly cationic character of the Cr(III) centers, which induces electrostatic polarization of the CO molecular orbitals on coordination to a metal center (40,41).…”

Section: Significancesupporting

confidence: 65%

Proton transfers are key elementary steps in ethylene polymerization on isolated chromium(III) silicates

Delley

Núñez‐Zarur

Conley

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

121

151

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Significance The Phillips catalyst—CrO x /SiO 2 —produces 40–50% of global high-density polyethylene, yet several fundamental mechanistic controversies surround this catalyst. What is the oxidation state and nuclearity of the active Cr sites? How is the first Cr–C bond formed? How does the polymer propagate and regulate its molecular weight? Here we show through combined experimental (infrared, ultraviolet-visible, X-ray near edge absorption spectroscopy, and extended X-ray absorption fine structures) and density functional theory modeling approaches that mononuclear tricoordinate Cr(III) sites immobilized on silica polymerize ethylene by the classical Cossee–Arlman mechanism. Initiation (C–H bond activation) and polymer molecular weight regulation (the microreverse of C–H activation) are controlled by proton transfer steps.

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Section: Significancesupporting

confidence: 65%

Proton transfers are key elementary steps in ethylene polymerization on isolated chromium(III) silicates

Delley

Núñez‐Zarur

Conley

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

121

151

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“…[16,17,25] Reaction (1) proceeds in anhydrous HF (aHF) solution in a different way, whereby the proton acts as oxidizing agent [Eq. (2)] and [Co(CO) 5 ]A C H T U N G T R E N N U N G [(CF 3 ) 3 BF] was isolated in 72 % yield. [11] …”

Section: A C H T U N G T R E N N U N G Lution [Co(co) 5 ]A C H T U N mentioning

confidence: 99%

“…Homoleptic metal carbonyl cations have a number of unique features that set them apart from other metal carbonyls: [1][2][3][4][5][6] 1) The cations, many of which are superelectrophilic, [7] are conveniently generated in conjugate Brønsted-Lewis superacids [8,9] such as HF-SbF 5 ; [1][2][3][4][5][6] 2) Salts of high thermal stability are formed with [Sb 2 F 11 ] À or less frequently [SbF 6 ] À or [BF 4 ] À as counteranions; [1][2][3][4][5][6]10] 3) These salts have been extensively characterized by single-crystal X-ray diffraction, as well as by spectroscopic (IR, Raman, 13 C NMR), thermochemical (DSC), and computational methods; [1][2][3][4][5][6] 4) The geometries of the cations are octahedral (d 6 ), squareplanar (d 8 ), or linear (d 10 ), whereby the last two geometries had been previously unknown for metal carbonyl complexes; [1][2][3][4][5][6] 5) The vast majority of metal carbonyl cations are formed by metals from the second (4d) and third (5d) transition series. [1]…”

Section: Introductionmentioning

confidence: 99%

“…[11] 2) In hexane solution [Co 2 (CO) 8 ] forms with (CF 3 ) 3 BCO a Lewis acid-base adduct [Co 2 (CO) 7 CO À BA C H T U N G T R E N N U N G (CF 3 ) 3 ], which has been structurally characterized. 3) [Co(CO) 3 NO] reacts with nitrosyl salts such as NO[BA C H T U N G T R E N N U N G (CF 3 ) 4 ] to give new cationic mixed carbonyl nitrosyl complexes, for example, [Co(CO) 2 …”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6] Due to the considerable oxidizing ability of SbF 5 , many feasible carbonyl monocations, such as [Co(CO) 5 ] + , [Cr(CO) 6 ] + , and [Ta(CO) 7 ] + , are not obtainable in HFSbF 5 , and other synthetic pathways are required, which employ Lewis acids incapable of oxidizing side reactions.…”

Section: Introductionmentioning

confidence: 99%

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Salts of the Cobalt(I) Complexes [Co(CO)₅]⁺ and [Co(CO)₂(NO)₂]⁺ and the Lewis Acid–Base Adduct [Co₂(CO)₇COB(CF₃)₃]

Bernhardt¹,

Finze²,

Willner³

et al. 2006

Chemistry A European J

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The reaction of [Co(2)(CO)(8)] with (CF(3))(3)BCO in hexane leads to the Lewis acid-base adduct [Co(2)(CO)(7)CO--B(CF(3))(3)] in high yield. When the reaction is performed in anhydrous HF solution [Co(CO)(5)][(CF(3))(3)BF] is isolated. The product contains the first example of a homoleptic metal pentacarbonyl cation with 18 valence electrons and a trigonal-bipyramidal structure. Treatment of [Co(2)(CO)(8)] or [Co(CO)(3)NO] with NO(+) salts of weakly coordinating anions results in mixed crystals containing the [Co(CO)(5)](+)/[Co(CO)(2)(NO)(2)](+) ions or pure novel [Co(CO)(2)(NO)(2)](+) salts, respectively. This is a promising route to other new metal carbonyl nitrosyl cations or even homoleptic metal nitrosyl cations. All compounds were characterized by vibrational spectroscopy and by single-crystal X-ray diffraction.

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Carbonyl Complexes of the Transition Metals

Calderazzo¹

2005

Encyclopedia of Inorganic Chemistry

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Carbon monoxide is a versatile ligand as it forms compounds with both transition metals and main group elements. Transition d metals of electronic configuration d n (0 < n < 10) form the most numerous class of these compounds, although recent progress has been made in expanding the area of existence toward main group, lanthanide (4f) and actinide (5f) metals. The most extensively studied series of carbonyl derivatives have the general formula [M(CO) n ] m , with n representing the coordination number of the central metal atom M, and m being the nuclearity of the system. In these compounds, the central metal atom is in the zero oxidation state. Starting from readily available inorganic derivatives in a positive oxidation state, the synthesis of these compounds normally requires a reducing agent capable of acting in the presence of carbon monoxide: in fact, only nickel metal, as a finely divided activated powder, is reactive toward CO leading to the corresponding derivative Ni(CO) 4 . The selection of the reducing agent varies as a function of the position of the metal M within the periodic table. There is a general trend of an increase in the nuclearity m toward the end of the transition d series, the nuclearity being related to the bonding arrangements of the CO ligand, which may act as terminal, doubly bridging or triply bridging. Metal carbonyls are characterized by IR‐active vibrations around 2000 cm −1 associated with the carbonyl groups. Vibrational spectra in solution give important information about: (a) the electronic distribution within the M–CO bond in terminally bonded carbonyl groups; (b) the molecular structure associated with the number of bands observed; (c) the type of bonding in dinuclear or polynuclear compounds. X‐ray diffraction data have been extensively used in order to define the molecular structure in the solid state. The metal–CO combinations span a wide range of oxidation states, derivatives being known for oxidation states from +III to −IV. Metal carbonyls undergo three types of reaction: (a) substitution of the carbonyl groups, whereby the oxidation state of the central metal atom remains unchanged, (b) oxidation, and (c) reduction. Carbonyl derivatives of early‐ and late transition metals present specific bonding and spectroscopic properties. Concerning the transition elements of groups 6–9, the M–CO bond dissociation enthalpy increases down the group, and is normally greater than the metal–metal bond enthalpy, the latter being estimated from the heat of atomization. From a mechanistic viewpoint, substitution and redox reactions have been studied extensively. A special case of substitution is the migratory carbonyl insertion, by which an M–R bond to a carbyl group R is converted by CO into the M–(CO)R sequence.

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Nonclassical Metal Carbonyls

Cited by 163 publications

References 326 publications

Proton transfers are key elementary steps in ethylene polymerization on isolated chromium(III) silicates

Proton transfers are key elementary steps in ethylene polymerization on isolated chromium(III) silicates

Salts of the Cobalt(I) Complexes [Co(CO)₅]⁺ and [Co(CO)₂(NO)₂]⁺ and the Lewis Acid–Base Adduct [Co₂(CO)₇COB(CF₃)₃]

Carbonyl Complexes of the Transition Metals

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Nonclassical Metal Carbonyls

Cited by 163 publications

References 326 publications

Proton transfers are key elementary steps in ethylene polymerization on isolated chromium(III) silicates

Proton transfers are key elementary steps in ethylene polymerization on isolated chromium(III) silicates

Salts of the Cobalt(I) Complexes [Co(CO)5]+ and [Co(CO)2(NO)2]+ and the Lewis Acid–Base Adduct [Co2(CO)7COB(CF3)3]

Carbonyl Complexes of the Transition Metals

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Resources

About

Salts of the Cobalt(I) Complexes [Co(CO)₅]⁺ and [Co(CO)₂(NO)₂]⁺ and the Lewis Acid–Base Adduct [Co₂(CO)₇COB(CF₃)₃]