Metal clusters in catalysis. 14. The chemistry of dinuclear metal-acetylene complexes

Muetterties, E. L.; Pretzer, W. R.; Thomas, M. G.; Beier, B. F.; Thorn, David L.; Day, Victor W.; Anderson, A. B.

doi:10.1021/ja00475a019

Cited by 80 publications

(25 citation statements)

References 8 publications

(11 reference statements)

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“…3 and Table 2b). The C(2)-C(3) length of 1.363 (8) A is within the range 1.28-1.39 A observed for other ~2-r/E-alkyne-bridged binuclear compounds (Muetterties, Pretzer, Thomas, Beier, Thorn, Day & Anderson, 1978), and is 0.09 A longer than the #2-r/L alkyne distance in (CsHs)2RhE(CO)E(CF3C2CF3) (Dickson, Johnson, Kirsch & Lloyd, 1977). The lengthening of the C-C bond indicates some reduction in bond order, and this is consistent with the observed decrease of v(C-C) from 1642 to 1592 cm -1 in the infrared spectra of (CsHs)2Rh2(CO)2(CF3C2CF 3) and (CsHs)2Rh2(CO)(CF3C 2CF3), respectively.…”

Section: Resultssupporting

confidence: 54%

The crystal and molecular structure of μ-carbonyl-bis(η-cyclopentadienyl)-μ-η-(hexafluoro-2-butyne)-dirhodium (Rh–Rh)

Dickson¹,

Pain²,

Mackay³

1979

Acta Crystallogr Sect B

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2321 rather large (see Fig. 3). For this reason an attempt was made to refine the structure in the noncentrosymmetric space group P6 a. Isotropic least-squares refinement converged with positional and isotropic thermal parameters equivalent within error to those obtained in the similar refinement in the centrosymmetric space group, except for atoms H(1A), H(1B), and H(2) on the ethyl sulfate group. However, attempts to continue refinement with anisotropic thermal parameters were unsuccessful, in that the temperature factors for the S atom and atom H(1A) became non-positive definite. It is our feeling that the true space group is P63/m, and that the large ellipsoids for the ethyl sulfate hydrogens are due to extreme thermal motion. It is possible that the H atoms are disordered, in which case a lowering of the local symmetry of the Y site is not completely ruled out. However, since the Y(OH2)39 + moiety still conformed, within error, to C3h site symmetry when refinement was attempted in the P63 space group, it is likely that the possible perturbation of the crystal-field levels of Yb 3+ (which partially substitutes Y in the crystals used in a spin refrigerator) would be extremely small. ) distance is 1.363 (8) A and the Rh-Rh length is 2.651 (1) A. The CO group is symmetrically bridging, and an approximate mirror plane passes through this group and the four C and two F atoms of the alkyne. The CO group is 0-43 A closer to one alkyne C than the other. The two (CsHs)Rh units are in an eclipsed orientation. References ABRAGAM, A. (1963

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Section: Resultssupporting

confidence: 54%

The crystal and molecular structure of μ-carbonyl-bis(η-cyclopentadienyl)-μ-η-(hexafluoro-2-butyne)-dirhodium (Rh–Rh)

Dickson¹,

Pain²,

Mackay³

1979

Acta Crystallogr Sect B

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“…dimetallated olefinic formulation for this group, are normally observed (6,8,10,(33)(34)(35)(36)(37)(38)(39). These distances are even substantially longer than that reported (1.33(1) A) in the dirhodium analogue (9) and in a number of related species (10,(40)(41)(42)(43) having a bridging diphenylacetylene group, where distances near 1.35 A appear typical. These distances in 3 are comparable to those between the acetylenic and carboxylate carbons (C (2)-X(3) = 1.48(1) A (1.45(1)A)), and as such are consistent with a loss of much of the multiple-bond character.…”

Section: Results and Compound Characterizationmentioning

confidence: 72%

Parallel vs. perpendicular alkyne coordination in binuclear complexes. The first examples of reactivity differences in isomers differing in their alkyne coordination modes

George¹,

McDonald²,

Cowie³

1996

Can. J. Chem.

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Abstract:The reaction of [Ir,(CO),(dppm),] (dppm = Ph,PCH,PPh,) with dimethyl acetylenedicarboxylate (DMAD) first yields [ I~~( c o )~(~, -~' :~~-D M A D ) (~~~~)~](2) in which the alkyne is bound parallel to the metal-metal axis and the diphosphines are bound in a trans arrangement at both metals. This metastable isomer slowly rearranges to the stable form, [ I~~( C O ) , (~, -~~:~~-D M A D ) (~~~~)~](3), in which the alkyne is now bound perpendicular to the metals and the diphosphines are bent back in a cis arrangement at both metals. The analogous species can be prepared by substituting hexafluoro-2-butyne (HFB) for DMAD; however, for the HFB adduct the isomer having the parallel geometry is seen only as a transient species; only Author to whom correspondence may be addressed. Telephone: (403) Can. J. Chem. Vol. 74, 1996 correspondant ainsi que des produits de dtcomposition. On a Ctabli la structure du composC 3 comme produit de solvatation double du chlorure de mtthylkne. Les donnCes cristallines sont les suivantes : 3.2CH,C12 : C6,H,4CI,06P41r2, monoclinique, groupe d'espace P2/c, a = 26,088(5) A, b = 9,896(4) A, c = 23,954(3) A, P = 109,27(1)", Z = 4, R(F) = 0,038, R,,(F~) = 0,0997 (tous les donnCes). [ I~~( C O )~(~, -~~:~~-H F B ) (~~~~)~]

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“…[13] Other sources of carbon added to 1, such as pentaphenylcyclopentadiene, C 60 , C 70 , anthracene, and ethynylbenzene, had a detrimental effect. On the other hand, performing the same set of experiments with [Ni(cod) 2 ]/PhC 2 Ph (2, 1:1; cod = cycloocta-1,5-diene), [14] a pyrophoric mixture prepared in the pyrolysis tubes at À80 8C, provided essentially identical (positive and negative) results: free-standing films of MWNTs (post acidic wash: elemental analysis: C 89.56 %, calcd for C 42 Ni: C 89.58 %) that were equally well graphitized, but with a larger (outer) diameter distribution of 40-90 nm, and containing a crystalline fcc arrangement of Ni atoms (Figure 3). [15] Again, the ratio of alkyne to metal complex could be increased successfully to 3:1 to provide a carbon yield based on the metal of > 1000 %, which compares favorably with CVD results.…”

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confidence: 99%

Near‐Quantitative Solid‐State Synthesis of Carbon Nanotubes from Homogeneous Diphenylethynecobalt and –Nickel Complexes

2003

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Carbon nanotubes (CNTs) have generated a tremendous amount of research interest because of their unique structural, electronic, magnetic, and mechanical properties. [1] Among the various synthetic methods employed for their preparation, chemical vapor deposition (CVD) has emerged to be most effective, and efforts are increasing in applying this technique to pre-growth device fabrication by utilizing (in particular lithographically) [2] patterned catalyst arrays and in situ tube assembly. [2,3] Crucial in this endeavor is the sitespecific batch production of ordered carbon with control of stoichiometry and ultimately morphology. One possible approach to achieving this would be the efficient thermal conversion of a defined, soluble, molecular organometallic precursor composed of both the carbon source and the metal catalyst, placed locospecifically by wetting and drying. Such a strategy would combine the advantages of the floating organometallic catalyst (for example, ferrocene, [Fe(CO) 5 ], etc.) CVD methodology [1d, 4] with a solid-state conversion of carbon precursors. Reports of the latter reveal some serious shortcomings with respect to yield and/or degree of graphitization, extremity of conditions, need for specialized equipment, the requirement of co-reagents, and simplicity of starting materials. [1d, 5] We have described the solid-state thermolysis of a [Co 2 (CO) 6 ]-complexed tetrabenzodehydro [20]annulene and some of its substructures to form ordered carbon material, but this method shared some of these drawbacks, in as much as the highest yields were only about 60 %. The desired product consisted of an (at best) approximately equal mixture of multiwalled tubes (MWNTs)

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Metal clusters in catalysis. 14. The chemistry of dinuclear metal-acetylene complexes

Cited by 80 publications

References 8 publications

The crystal and molecular structure of μ-carbonyl-bis(η-cyclopentadienyl)-μ-η-(hexafluoro-2-butyne)-dirhodium (Rh–Rh)

The crystal and molecular structure of μ-carbonyl-bis(η-cyclopentadienyl)-μ-η-(hexafluoro-2-butyne)-dirhodium (Rh–Rh)

Parallel vs. perpendicular alkyne coordination in binuclear complexes. The first examples of reactivity differences in isomers differing in their alkyne coordination modes

Near‐Quantitative Solid‐State Synthesis of Carbon Nanotubes from Homogeneous Diphenylethynecobalt and –Nickel Complexes

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