Preparation and NMR spectra of B5H9Fe(CO)3, an analog of hexaborane(10)

Shore, Sheldon G.; Ragaini, J. D.; Smith, Richard L.; Cottrell, Charles E.; Fehlner, Thomas P.

doi:10.1021/ic50193a028

Cited by 27 publications

(6 citation statements)

References 5 publications

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“…The two BHB and two ReHB hydrogens can be placed as shown in either Chart a or 3b. The former constitutes a static structure, whereas in the latter the ReHB hydrogens must flip back and forth between the two adjacent boron atoms rapidly on the NMR time scale: a fluxional process with precedent in metallaborane chemistry . The Re−Re distance of 5 is about 0.15 Å longer than found in 1 − 4 ; however, it is nearly the same as the W−W distance in closed (Cp*WH) 2 B 7 H 7 , which also contains bridging hydrogen atoms …”

Section: Results: Syntheses and Geometric Structurementioning

confidence: 95%

Synthesis and Characterization of Hypoelectronic Rhenaboranes. Analysis of the Geometric and Electronic Structures of Species Following Neither Borane nor Metal Cluster Electron-Counting Paradigms

et al. 2004

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The reaction of (CpReH(2))(2)B(4)H(4) with monoborane leads to the sequential formation of (CpRe)(2)B(n)()H(n)() (n = 7-10, 1-4). These species adopt closed deltahedra with the same total connectivities as the closo-borane anions [B(n)()H(n)()](2)(-), n = 9-12, but with flattened geometries rather than spherical shapes. These rhenaborane clusters are characterized by high metal coordination numbers, Re-Re cross-cluster distances within the Re-Re single bond range, and formal cluster electron counts three skeletal electron pairs short of that required for a canonical closo-structure of the same nuclearity. An open cluster, (CpReH)(2)B(7)H(9) (5), is isolated that bears the same structural relationship to arachno-B(9)H(15) as 1-4 bear to the closo-borane anions. Chloroborane permits the isolation of (CpReH)(2)B(5)Cl(5) (6), an isoelectronic chloro-analogue of known open (CpWH(2))(2)B(5)H(5) and (CpRe)(2)B(6)H(4)Cl(2) (7), a triple-decker complex containing a planar, six-membered 1,2-B(6)H(4)Cl(2) ring. Both are putative five- and six-boron intermediates in the formation of 1. Electronic structure calculations (extended Hückel and density functional theory) yield geometries in agreement with the structure determinations, large HOMO-LUMO gaps in accord with the high stabilities, and (11)B chemical shifts accurately reflecting the observed shifts. Analyses of the bonding in 1-4 reveal that the CpRe.CpRe interaction generates fragment orbitals that are able to contribute the "missing" three skeletal electron pairs required for skeletal bonding. The necessity of a Re.Re interaction for strong cluster bonding requires a borane fragment shape change to accommodate it, thereby explaining the noncanonical geometries. Application of the debor principle of borane chemistry to the shapes of 1-4 readily rationalizes the observed geometries of 5 and 6. This evidence of the scope of transition metal fragment control of borane geometry suggests the existence of a large class of metallaboranes with structures not found in known borane or metal clusters.

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Section: Results: Syntheses and Geometric Structurementioning

confidence: 95%

Synthesis and Characterization of Hypoelectronic Rhenaboranes. Analysis of the Geometric and Electronic Structures of Species Following Neither Borane nor Metal Cluster Electron-Counting Paradigms

et al. 2004

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“…This latter downfield shifting of the coordinated basal boron resonance is consistent with metal coordination at a basal boron atom by replacement of a terminal hydrogen atom. [30][31][32][33][34] The magnitude of this downfield shift relative to pentaborane(9) is, however, unusually large and represents the largest downfield shift reported for an exo-substituted pentaborane species (A(5(complex) -5-(B5H9)) = +37.0 ppm).9 This shift is considerably further downfield than either complex 4 ( = +21.9 ppm) or the related [B5H8(Fe(n5-C5H5)(CO)2)2] complex ( = +15.4 ppm).10 This indicates that significant electron density has shifted from the basal-boron position to B(2), B(3), and the exopolyhedral substitutents of the cage system and that this electron density shift is clearly enhanced by the presence of the bridging phosphino group. The complex basal resonances at -23.6 and -24.9 ppm decouple to clearly show B-P coupled doublets.…”

Section: Resultsmentioning

confidence: 99%

Small heteroborane cluster systems. 3. Characterization, deprotonation, and transition-metal chemistry of the small phosphorus-bridged pentaborane(9) system (.mu.-diphenylphosphino)pentaborane

Goodreau¹,

Ostrander²,

Spencer³

1991

Inorg. Chem.

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“…Subsequent elution with ether afforded a red-orange solution, which was dried to yield 0.083 g of red-orange microcrystals of 12 (80% based on Rh). MS(EI): P + ) 690, 3 B, 1 Cl, and 2 Rh atoms; fragment peaks corresponding to sequential loss of 3 CO; calcd for 12 C23 1 H33 16 O3 11 B3 59 Co 103 Rh2 35 Cl, 689.9853; obsd, 689.9866. NMR: 11 B (hexane, 22 °C), δ 62.8 (s, { 1 H}, s, 1B), 37.4 (d, JB-H ) 150 Hz, { 1 H}, s, 2B); 1 H (C6D6, 22 °C), δ 5.50 (pcq, 2H, B-Ht), 1.67 (s, 30H, C5Me5), -7.07 (br, 1H, B-H-B).…”

Section: (M) Closo-1-cl-6-{co(co)2}-23-(cp*rh)2(µ3-co)b3h3mentioning

confidence: 99%

“…Examples of monometallahexaboranes are known, e.g., 2-(CO) 3 FeB 5 H 9 (Chart 1). 59 But cluster 2 is the first example of a structurally characterized dimetallahexaborane analogous to B 6 H 10 in which the apical BH and a basal BH are subrogated by Cp*RuH; i.e., in contrast to a hypothetical nido-1,2-{(CO) 3 Fe} 2 B 4 H 8 dimetallahexaborane (Chart 1), 2 possesses two additional endo hydrogen atoms. Thus, all five edges of the pentagonal open face are bridged by hydrogen atoms as is the Ru-Ru apical-basal edge.…”

Section: Syntheses Of Nido-3-cl-12-(cp*rh)mentioning

confidence: 99%

Chemistry of Dimetallaboranes Derived from the Reaction of [CpMCl₂]₂with Monoboranes (M = Ru, Rh; Cp = η⁵-C₅Me₅)

1999

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In a single step, from [Cp*RuCl 2 ] 2 (Cp* ) η 5 -C 5 Me 5 ) and Li [BH 4 ], nido-1,2-(Cp*Ru) 2 (µ-H) 2 B 3 H 7 , 1, is produced in high yield. Addition of BH 3 ‚THF to 1 results in conversion to nido-1,2-(Cp*Ru) 2 (µ-H)B 4 H 9 , 2. Reaction of BH 3 ‚THF directly with [Cp*RuCl 2 ] 2 yields a mixture of 1 and 2. In two steps, a rhodium analogue, nido-2,3-(Cp*Rh) 2 B 3 H 7 , 9, is accessible by the reaction of [Cp*RhCl 2 ] 2 and Li [BH 4 ] to exclusively produce (Cp*Rh) 2 B 2 H 6 , 8, which adds BH 3 ‚THF to give 9 as the major product in a mixture. Reaction of BH 3 ‚THF directly with [Cp*RhCl 2 ] 2 yields the chloro derivative of 9, nido-1-Cl-2,3-(Cp*Rh) 2 B 3 H 6 , 11, in high yield via the intermediate positional isomer, nido-3-Cl-1,2-(Cp*Rh) 2 B 3 H 6 , 10. With high concentrations of Co 2 (CO) 8 , 1 reacts with Co 2 (CO) 8 to give nido-1-(Cp*Ru)-2-(Cp*RuCO)-3-Co(CO) 2 (µ 3 -CO)B 3 H 6 , 3, whereas low concentrations permit competitive degradation of 1 to yield arachno-(Cp*Ru)(CO)(µ-H)B 3 H 7 , 4. On the other hand, reaction of 11 with Co 2 (CO) 8 gives closo-1-Cl-6-{Co(CO) 2 }-2,3-(Cp*Rh) 2 (µ 3 -CO)B 3 H 3 , 12. Mild thermolysis of 3 results in loss of hydrogen and the formation of closo-6-Co(CO) 2 -2,3-(Cp*Ru) 2 (µ-CO)(µ 3 -CO)B 3 H 4 , 5, whereas thermolysis of 2 results in loss of hydrogen and formation of pileo-2,3-(Cp*Ru) 2 B 4 H 8 , 6, with a BH-capped square pyramidal structure. Finally, 6 reacts with Fe 2 (CO) 9 to yield pileo-6-Fe(CO) 3 -2,3-(Cp*Ru) 2 (µ 3 -CO)B 4 H 4 , 7, with a BH-capped octahedral cluster structure. The overall isolated yield of 7, formed in four steps from [Cp*RuCl 2 ] 2 , is ≈50% and evidences good control of reactivity.

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Preparation and NMR spectra of B5H9Fe(CO)3, an analog of hexaborane(10)

Cited by 27 publications

References 5 publications

Synthesis and Characterization of Hypoelectronic Rhenaboranes. Analysis of the Geometric and Electronic Structures of Species Following Neither Borane nor Metal Cluster Electron-Counting Paradigms

Synthesis and Characterization of Hypoelectronic Rhenaboranes. Analysis of the Geometric and Electronic Structures of Species Following Neither Borane nor Metal Cluster Electron-Counting Paradigms

Small heteroborane cluster systems. 3. Characterization, deprotonation, and transition-metal chemistry of the small phosphorus-bridged pentaborane(9) system (.mu.-diphenylphosphino)pentaborane

Chemistry of Dimetallaboranes Derived from the Reaction of [CpMCl₂]₂with Monoboranes (M = Ru, Rh; Cp = η⁵-C₅Me₅)

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Preparation and NMR spectra of B5H9Fe(CO)3, an analog of hexaborane(10)

Cited by 27 publications

References 5 publications

Synthesis and Characterization of Hypoelectronic Rhenaboranes. Analysis of the Geometric and Electronic Structures of Species Following Neither Borane nor Metal Cluster Electron-Counting Paradigms

Synthesis and Characterization of Hypoelectronic Rhenaboranes. Analysis of the Geometric and Electronic Structures of Species Following Neither Borane nor Metal Cluster Electron-Counting Paradigms

Small heteroborane cluster systems. 3. Characterization, deprotonation, and transition-metal chemistry of the small phosphorus-bridged pentaborane(9) system (.mu.-diphenylphosphino)pentaborane

Chemistry of Dimetallaboranes Derived from the Reaction of [Cp*MCl2]2with Monoboranes (M = Ru, Rh; Cp* = η5-C5Me5)

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Chemistry of Dimetallaboranes Derived from the Reaction of [CpMCl₂]₂with Monoboranes (M = Ru, Rh; Cp = η⁵-C₅Me₅)