Metal atom synthesis of metallaboron clusters. 8. Synthesis of new cobalt, iron, and nickel clusters derived from 2,6-C2B7H11. Structural characterization of 2-[.eta.6-C6(CH3)3H3]Fe-1,6-C2B7H9, 6-[.eta.6-C6(CH3)3H3]Fe-9,10-C2B7H11, and 5,7,8-(CH3)3-11,7,8,10-[.eta.3-C4(CH3)4H]NiC3B7H7

Briguglio, James J.; Sneddon, Larry G.

doi:10.1021/om00133a023

Cited by 32 publications

(4 citation statements)

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“…This may be a consequence of the increased electron density upon the metal following CO → PEt 3 substitution, but it can be dangerous to read too much into such shifts . In their 1 H NMR spectra, broad signals are seen for the cage {CH} units at δ 6.16 ( 3 ) and 6.00 ( 4 ), typical for a four-connected {CH} vertex in 10-vertex clusters, , while the hydroxyl hydrogens resonate at δ 3.68 ( 3 ) and 3.69 ( 4 ) in the same spectra. Correspondingly, the two distinct types of cage carbon atom appear at very different positions in the 13 C{ 1 H} NMR spectra: the {CH} units give rise to broad signals at δ 80.4 ( 3 ) and 78.5 ( 4 ), whereas the {COH} groups resonate far downfield at δ 177.3 ( 3 ) and 184.5 ( 4 ).…”

Section: Resultsmentioning

confidence: 99%

A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)₄} into 8-Vertex [closo-1-CB₇H₈]⁻: Synthesis and Reactivity Studies

2008

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Reaction of [NBu n4 ][closo-1-CB 7 H 8 ] with [Fe 2 (CO) 9 ] in refluxing THF (tetrahydrofuran) gives the neutral ferradicarborane [2,2,2-(CO) 3 -1-OH-closo-2,1,10-FeC 2 B 7 H 8 ] (3), which, upon treatment with PEt 3 in the presence of Me 3 NO, yields [2,2-(CO) 2 -2-PEt 3 -1-OH-closo-2,1,10-FeC 2 B 7 H 8 ] (4). In 3 and 4 the 10-vertex {FeC 2 B 7 } cluster has two carbon vertices in antipodal, four-connected positions and the iron atom in a five-coordinate site adjacent to a carbon vertex that bears an OH substituent. Treatment of 4 in THF with NaH and then R-X (X ) 8)). The pendant allyl group in 6 becomes η 2 -bonded to the iron center upon treatment with Me 12), in which a {C 2 Co 2 } tetrahedron is linked to the 10-vertex {FeC 2 B 7 } cluster by an -OCH 2bridge. Heating compound 7 with [Co(CO) 2 (η-C 5 H 5 )] in refluxing toluene gives the complex [2,2-(CO) 2 -2-PEt 3 -1,4-µ-{OC(H)dC(Me)-B}-closo-2,1,10-FeC 2 B 7 H 7 ] (13a), which contains a 5-membered ring that involves one carbon vertex and an adjacent boron atom. Compound 13a yields [2-CO-2,2-(PEt 3 ) 2 -1,4-µ-{OC(H)dC(Me)-B}-closo-2,1,10-FeC 2 B 7 H 7 ] (13b) upon addition of further PEt 3 in the presence of Me 3 NO. Treatment of compounds 7 and 8 with PEt 3 in CH 2 Cl 2 and in the presence of Me 3 NO affords the zwitterionic ylide species [2-CO-2-PEt 3 -1,2-µ-{OCH 2 C{dC(R′)PEt 3 }}-closo-2,1,10-FeC 2 B 7 H 8 ] (R′ ) H (15), Me (17), respectively). In the latter pair, an -OCH 2 C{dC(R′)PEt 3 } group bonded to a cage carbon atom is also directly σ-bonded (at the β-position) to the adjacent iron vertex, forming a 5-membered ring. The novel structural features of compounds 4, 10, 12, 13, 15, and 17 have been confirmed by single-crystal X-ray diffraction studies.

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Section: Resultsmentioning

confidence: 99%

A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)₄} into 8-Vertex [closo-1-CB₇H₈]⁻: Synthesis and Reactivity Studies

2008

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“…Alterations of the overall shielding (/(total) = (/(para) + (/(dia) are almost exclusively brought about by the paramagnetic de-shielding term, which correlates with the mean HOMO-LUMO gap AE, the vanadium LCAO coefficients C(3d) and C(4p) of MOs taking part in electronic transitions, and the delocalization of 3d and 4p electrons, r, in the following manner: i/(para) = const X [(^&) + (r3C2)3d] (1) with the main contribution coming from transitions between orbitals with large V(3d) population.1217 As shown in Figure 3 for VOX3 (X = Br, = +432;20a X = Cl, = 0; X = F, cá. -70017b), contributing HOMOs are u(VX), tt(VX) and ir(V=0) bonding orbitals in the case of VOBr3 and VOCl3, and tr(V=0) only for VOF3.…”

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confidence: 99%

“…;2-carboxylato and -carbonato complexes) and 3-ring structures (e.g. peroxo complexes) give rise to overlap perturbations and thus to diminished oxygen donation into V(3d) and V(4p) orbitals and hence a net depletion of electron population resulting in decreased C2 in (1). Alternatively, delocalization of bonding electron density over the threeor four-membered ring can give rise to an increase of r, which in turn diminishes m'(para).…”

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confidence: 99%

Vanadium-51 shielding in vanadium(V) complexes: a reference scale for vanadium binding sites in biomolecules

Rehder¹,

Weidemann²,

Duch³

et al. 1988

Inorg. Chem.

177

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The role of vanadium as a biometal is well established1 and encompasses stimulating and regulatory* as well as inhibitory functions, e.g. toward N~, K -A T P~s~.~ Vanadium has also been recognized as an essential element in photosynthesis: as a storage for redox potentials in the "blood" of ascidian^,^ and as an integral part in amavadine, a hydroxamate complex of V occurring in A m a n i t a muscaria.6 Lately, vanadium has adopted t h e status of an catalytically active center in t h e nitrogenase system of a special strain of Azotobacter chroococcuml and in the vanadate(V)-dependent halide peroxidases of several marine brown algae such as Ascophyllum n o d o~u m .~*~ Further, t h e binding of V(1V) and V(V) to serum transferrin has been documented.lO~ll More recently, the excellent NMR properties of the 51V nu-cleus12 have been exploited in the evaluation of the interaction between vanadate(V) and large biomolecules such as ribo-n~clease,'~ transferrin," and peroxidase from A . nodosum,14 the latter being the first 51V NMR detection of an enzyme containing vanadate(V) as the prosthetic group.In order to provide a basis for t h e interpretation of vanadium NMR data of biological material, we report here on a referencing scale for 51V chemical shifts, 6(51V), incorporating t h e presently available shift data on V5+ compounds (including recent work on the interaction between vanadate and biorelevant ligandsI5), (a) Chasteen, N. D. Strucr. Bonding (Berlin) 1983,53, 105. (b) Kustin, K.; McLecd, G. C.; Gilbert, T. A.; Briggs, L. R., 4th. Eady, R. R.; Richardson, T. H.; Miller, R. W.; Hawkins, M.; Postgate, J. R. Nature (London) 1986, 322, 388. (b) Arber, J. M.; Dobson, B. R.; Eady. R. R.; Stevens, P.; Hasnain, S. S.; Garner, C. D.; Smith, B. E. Nature (London) 1987, 325, 372. (a) Vilter, H. Bot. Mar. 1983, 26,451. (b) Vilter, H. Phytochemisfry 19848 23, 1387. de Boer, E.; van Kooyk, Y.; Tromp, M. G. M.; Plat, H.; Wever, R.

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“…Metal atom synthesis has been used widely in organometallic chemistry and can be used in metallacarborane syntheses. This methodology has been profitably exploited by Sneddon and co-workers in the syntheses of a number of unusual metallacarboranes. − The reaction of thermally generated cobalt atoms with hexaborane(10), bis(trimethylsilyl)acetylene, and cyclopentadiene gave a mixed-ligand complex, 5,1‘,2‘-[1-(η- C 5 H 5 )Co-2,3-(Me 3 Si) 2 C 2 B 4 H 3 ][B 2 H 5 ], as the major product . This unusual complex consists of a unique bridged structure of a [1-(η-C 5 H 5 )Co-2,3-(Me 3 Si) 2 C 2 B 4 H 3 ] sandwich in which the terminal hydrogen on the unique boron is replaced by a B 2 H 5 moiety via a three-center B−B−B bond.…”

Section: Metallacarboranes Of D-block Elementsmentioning

confidence: 99%

Evolution of C₂B₄Carborane Chemistry: from Early Years to the Present

Hosmane

Maguire

2005

Organometallics

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A review of the chemistry of polyhedral cluster complexes in which s-, p-, d- and f-block metals are incorporated mainly into C cage -trimethylsilyl-substituted C2B4 carborane cages is presented. While the main thrust of this review is on the results obtained in authors' laboratories, comparisons are made to similar systems and to those involving both large- and small-cage carboranes. In this way we hope to demonstrate the unique chemistry of the small-C2B4-cage systems that has emerged over the last 40 years. However, a full picture of the chemistry of these systems cannot be presented without heavy reference to the larger, more stable 11- and 12-vertex cages, which in many ways preceded their more diminutive cousins. The focus of much of the current research is directed toward systematizing the chemistry of metallacarboranes with the aim of promoting their use as possible electronic, ceramic, and/or catalytic materials. However, such endeavors are based on our knowledge about the fundamental interactions that are at work in determining the structures and properties of these cluster complexes. This review attempts to provide such an overview of small-cage heterocarborane chemistry.

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Metal atom synthesis of metallaboron clusters. 8. Synthesis of new cobalt, iron, and nickel clusters derived from 2,6-C2B7H11. Structural characterization of 2-[.eta.6-C6(CH3)3H3]Fe-1,6-C2B7H9, 6-[.eta.6-C6(CH3)3H3]Fe-9,10-C2B7H11, and 5,7,8-(CH3)3-11,7,8,10-[.eta.3-C4(CH3)4H]NiC3B7H7

Cited by 32 publications

References 2 publications

A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)₄} into 8-Vertex [closo-1-CB₇H₈]⁻: Synthesis and Reactivity Studies

A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)₄} into 8-Vertex [closo-1-CB₇H₈]⁻: Synthesis and Reactivity Studies

Vanadium-51 shielding in vanadium(V) complexes: a reference scale for vanadium binding sites in biomolecules

Evolution of C₂B₄Carborane Chemistry: from Early Years to the Present

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Metal atom synthesis of metallaboron clusters. 8. Synthesis of new cobalt, iron, and nickel clusters derived from 2,6-C2B7H11. Structural characterization of 2-[.eta.6-C6(CH3)3H3]Fe-1,6-C2B7H9, 6-[.eta.6-C6(CH3)3H3]Fe-9,10-C2B7H11, and 5,7,8-(CH3)3-11,7,8,10-[.eta.3-C4(CH3)4H]NiC3B7H7

Cited by 32 publications

References 2 publications

A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)4} into 8-Vertex [closo-1-CB7H8]−: Synthesis and Reactivity Studies

A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)4} into 8-Vertex [closo-1-CB7H8]−: Synthesis and Reactivity Studies

Vanadium-51 shielding in vanadium(V) complexes: a reference scale for vanadium binding sites in biomolecules

Evolution of C2B4Carborane Chemistry: from Early Years to the Present

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A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)₄} into 8-Vertex [closo-1-CB₇H₈]⁻: Synthesis and Reactivity Studies

A 10-Vertex Iron−Dicarbollide System Formed by Insertion of {Fe(CO)₄} into 8-Vertex [closo-1-CB₇H₈]⁻: Synthesis and Reactivity Studies

Evolution of C₂B₄Carborane Chemistry: from Early Years to the Present