14‐Vertex Heteroboranes with 14 Skeletal Electron Pairs: An Experimental and Computational Study

Robertson, Alasdair P. M.; Beattie, Nicholas A.; Scott, Greig; Man, Wing Y.; Jones, John; Macgregor, Stuart A.; Rosair, Georgina M.; Welch, Alan J.

doi:10.1002/anie.201602440

Cited by 14 publications

(6 citation statements)

References 44 publications

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“…We suggest that the origin of the unexpected product 6 is Direct Electrophilic Insertion (DEI) of a {CoCp*} + fragment into the anionic species [ 4 ] − or, more likely, [ 5 ] − prior to aerial oxidation. DEI was first recognized as a route to bimetallacarboranes by Kudinov and co-workers, and we have previously used it to deliberately prepare 14-vertex bimetallacarboranes from 13-vertex monometallacarborane anions. ,, In the 1 H NMR spectrum of 6 there are, in addition to the singlet arising from the 30 Cp* protons, two broad integral-1 C cage H resonances at δ 3.80 and 1.26 ppm. By analogy with [6-(1′- closo -1′,2′-C 2 B 10 H 11 )-4-( p -cymene)-5-(mesitylene)- closo -4,5,1,6-Ru 2 C 2 B 9 H 10 ], the closest fully characterized compound in the literature, we assign the lower-frequency C cage H resonance in 6 to C1 H .…”

Section: Resultsmentioning

confidence: 99%

Heterometalation of 1,1′-Bis(ortho-carborane)

2018

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Deboronation of [8-(1'- closo-1',2'-CBH)- closo-2,1,8-MCBH] affords diastereoisomeric mixtures of [8-(7'- nido-7',8'-CBH)- closo-2,1,8-MCBH] anions (1, M = Ru( p-cymene); 2, M = CoCp) isolated as [HNMe] salts. Deprotonation of 1 and reaction with CoCl/NaCp followed by oxidation yields [8-(1'-3'-Cp -closo-3',1',2'-CoCBH)-2-( p-cymene)- closo-2,1,8-RuCBH] isolated as two separable diastereoisomers, namely, 3α and 3β, the first examples of heterometalated derivatives of 1,1'-bis( ortho-carborane). Deprotonation of [7-(1'- closo-1',2'-CBH)- nido-7,8-CBH], metalation with CoCl/NaCp* and oxidation affords the isomers [1-(1'- closo-1',2'-CBH)-3-Cp*- closo-3,1,2-CoCBH] (4) and [8-(1'- closo-1',2'-CBH)-2-Cp*- closo-2,1,8-CoCBH] (5) as well as a trace amount of the 13-vertex/12-vertex species [12-(1'- closo-1',2'-CBH)-4,5-Cp*- closo-4,5,1,12-CoCBH] (6). Reduction then reoxidation of 4 converts it to 5. Deboronation of either 4 or 5 yields a diastereoisomeric mixture of [8-(7'- nido-7',8'-CBH)-2-Cp*- closo-2,1,8-CoCBH] (7), again isolated as the [HNMe] salt. Deprotonation of this followed by treatment with [RuCl( p-cymene)] produces [8-(1'-3'-( p-cymene)- closo-3',1',2'-RuCBH)-2-Cp*- closo-2,1,8-CoCBH] (8) as a mixture of two diastereoisomers in a 2:1 ratio, which could not be separated. Diastereoisomers 8 are complementary to 3α and 3β in which {CoCp} and {Ru( p-cymene)} in 3 were replaced by {Ru( p-cymene)} and {CoCp*}, respectively, in 8. Finally, thermolysis of mixture 8 in refluxing dimethoxyethane yields [8-(8'-2'-( p-cymene)- closo-2',1',8'-RuCBH)-2-Cp*- closo-2,1,8-CoCBH] (9), again as a 2:1 diastereoisomeric mixture that could not be separated. All new species were characterized by multinuclear NMR spectroscopy, and 3α, 3β, 4, 5, 6, and 9 were also characterized crystallographically.

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Section: Resultsmentioning

confidence: 99%

Heterometalation of 1,1′-Bis(ortho-carborane)

2018

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“…Carboranes are useful building blocks for ligand and catalyst design in organometallic chemistry . Polyhedral boron clusters can exhibit both π- and σ-interaction with transition metals providing a combination of high steric hindrance and unique electronic effects with their C–M, B–M, or B–H···M coordination to a metal center …”

Section: Introductionmentioning

confidence: 99%

Polyhedral Rearrangements in the Complexes of Rhodium and Iridium with Isomeric Carborane Anions [7,8-Me₂-X-SMe₂-7,8-nido-C₂B₉H₈]⁻ (X = 9 and 10)

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Polyhedral rearrangement of iridacarborane 1,2-Me2-3,3-(cod)-4-SMe2-3,1,2-closo-IrC2B9H8 (1) proceeds in a solution at RT and affords a product of 1,2 → 1,7 isomerization 1,8-Me2-2,2-(cod)-7-SMe2-2,1,8-closo-IrC2B9H8 (2). Rhodium derivative 1,2-Me2-3,3-(cod)-4-SMe2-3,1,2-closo-RhC2B9H8 (3) is significantly more stable toward heating than iridium complex 1 and isomerizes at 110 °C by 1,2 → 1,2 and 1,2 → 1,7 reaction schemes with 1,2 → 1,2 being the predominant route forming 1,2-Me2-4,4-(cod)-8-SMe2-4,1,2-closo-RhC2B9H8 (4) and 1,8-Me2-2,2-(cod)-7-SMe2-2,1,8-closo-RhC2B9H8 (5). Complexes 4 and 5 were characterized by 11B{1H}–11B{1H} COSY NMR spectrometry. A mechanism of 1,2 → 1,2 isomerization of 3 to 4 was proposed on the basis of DFT calculations. Reaction of the thallium salt Tl[7,8-Me2-9-SMe2-7,8-nido-C2B9H8] (CarbTl) with [Cp*RuCl]4 in THF furnishes new ruthenacarborane 1,2-Me2-3-(Cp*)-4-SMe2-3,1,2-closo-RuC2B9H8 (6). Heating of 6 at 80 and 144 °C leads to the partial and complete decomposition, respectively. Interaction of CarbTl with [Cp*IrCl2]2 in the presence of TlPF6 provides two new Ir(III) complexes [1,2-Me2-3-(Cp*)-4-SMe2-3,1,2-closo-IrC2B9H8]PF6 (7PF6) and 1,2-Me2-3-(Cp*)-4-SMe-3,1,2-closo-IrC2B9H8 (8) both stable upon heating in boiling tetrachloroethane (146 °C). A new 10-substituted charge-compensated carborane [7,8-Me2-10-SMe2-7,8-nido-C2B9H9] (9) was synthesized via an interaction of dicarbollide dianion [7,8-Me2-7,8-nido-C2B9H9]2– with dimethyl sulfide and acetaldehyde in acidic media. Thallium salt of 9 Tl[7,8-Me2-10-SMe2-7,8-nido-C2B9H8] (10) reacts with [(cod)IrCl]2 furnishing positional isomer of 1 with a symmetrical emplacement of SMe2 substituent complex 1,2-Me2-3,3-(cod)-8-SMe2-3,1,2-closo-IrC2B9H8 (11). Iridacarborane 11 requires elevated temperatures to undergo cage isomerization and converts upon heating at 110 °C to two new compounds 1,8-Me2-2,2-(cod)-11-SMe2-2,1,8-closo-IrC2B9H8 (12) and 1,2-Me2-4,4-(cod)-9-SMe2-4,1,2-closo-IrC2B9H8 (13) as a result of 1,2 → 1,7 and 1,2 → 1,2 rearrangements respectively with 13 being the minor product. The structures of 2, 6, 7PF6, 8, 10, 12, and 13 were determined by single-crystal X-ray diffraction.

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“…Entries in italics refer to 17-e compounds. 1 These structures differ in that NITWOC contains solvate; 2 dppp 3 = diphenylphosphinopropane; 3 2,4-dppp 5 = 2,4-diphenylphosphinopentane; 4 1,5-dppp 5 = 1,5-diphenylphosphinopentane.…”

Section: Elo Of κ 1 Ligandsmentioning

confidence: 99%

“…The |θ Cl | values of the 12 compounds in Table 5 all fall within the small circle superimposed on Figure 10. Further examples of [L 3 MC 2 B 9 H 11 ] metallacarboranes in which one ligand has a smaller STE than the other two include (stronger ligands given first) [ 1 These structures differ in that NITWOC contains solvate; 2 dppp3 = diphenylphosphinopropane; 3 2,4-dppp5 = 2,4-diphenylphosphinopentane; 4 1,5-dppp5 = 1,5-diphenylphosphinopentane.…”

Section: Elo Of κ 1 Ligandsmentioning

confidence: 99%

“…As an illustration of the importance of crystallographic studies to the field, of 735 entries in a recent listing of selected 12-vertex transition-element metallacarboranes [3], 449 were characterised by single-crystal diffraction studies. Metallacarboranes are 3-dimensional cluster compounds that in general can exist in a number of isomeric forms which cannot always be distinguished spectroscopically, in which case crystallographic study is the essential experimental technique [4]. A good example concerns the icosahedral metallacarboranes MC 2 B 9 for which there are nine possible isomers (Figure 1), eight of which have been reported for the ubiquitous [CpCoC 2 B 9 H 11 ] [5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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What Can We Learn from the Crystal Structures of Metallacarboranes?

Welch

2017

Crystals

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The determination of the molecular structures of metallacarboranes by X-ray diffraction remains critical to the development of the field, in some cases being the only viable way in which the overall architecture and the isomeric form of the molecule can be established. In such studies one problem frequently met is how to distinguish correctly {BH} and {CH} vertices, and this review begins by describing two relatively new methods, the Vertex-Centroid Distance (VCD) and Boron-Hydrogen Distance (BHD) methods, that have been developed to overcome the problem. Once the cage C atoms are located correctly, the resulting metallacarborane structure can frequently be analysed on the basis that cage B has a greater Structural Trans Effect (STE) than does cage C. In the absence of significant competing effects this gives rise to unequal M-L distances for a homogeneous ligand set and to a preferred Exopolyhedral Ligand Orientation (ELO) for a heterogeneous ligand set. ELO considerations can be used, amongst other things, to rank order the STEs of ligands and to identify suspect (in terms of cage C atom positions) metallacarborane structures.

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14‐Vertex Heteroboranes with 14 Skeletal Electron Pairs: An Experimental and Computational Study

Cited by 14 publications

References 44 publications

Heterometalation of 1,1′-Bis(ortho-carborane)

Heterometalation of 1,1′-Bis(ortho-carborane)

Polyhedral Rearrangements in the Complexes of Rhodium and Iridium with Isomeric Carborane Anions [7,8-Me₂-X-SMe₂-7,8-nido-C₂B₉H₈]⁻ (X = 9 and 10)

What Can We Learn from the Crystal Structures of Metallacarboranes?

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14‐Vertex Heteroboranes with 14 Skeletal Electron Pairs: An Experimental and Computational Study

Cited by 14 publications

References 44 publications

Heterometalation of 1,1′-Bis(ortho-carborane)

Heterometalation of 1,1′-Bis(ortho-carborane)

Polyhedral Rearrangements in the Complexes of Rhodium and Iridium with Isomeric Carborane Anions [7,8-Me2-X-SMe2-7,8-nido-C2B9H8]− (X = 9 and 10)

What Can We Learn from the Crystal Structures of Metallacarboranes?

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Polyhedral Rearrangements in the Complexes of Rhodium and Iridium with Isomeric Carborane Anions [7,8-Me₂-X-SMe₂-7,8-nido-C₂B₉H₈]⁻ (X = 9 and 10)