Crystal and molecular structure of bis-9-m-carboranylbromonium borofluoride

Yanovskii, A. I.; Struchkov, Yu. T.; Grushin, Vladimir V.; Tolstaya, T. P.; Demkina, I. I.

doi:10.1007/bf00744000

Cited by 5 publications

(5 citation statements)

References 8 publications

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“…The C-Si-C angles reflect tetrahedrality at silicon (109°), and the bond angle at bromine is 109°( by VSEPR theory and X-ray structure). 43 The formal representation of a silylium ion is given as structure III in Figure 2. The C-Si-C angles reflect trigonal planarity (120°), and there is no Si-Br bond.…”

Section: Resultsmentioning

confidence: 99%

The Silylium Ion (R3Si+) Problem: Effect of Alkyl Substituents R

Xie¹,

Bau²,

Benesi³

et al. 1995

Organometallics

102

141

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The X-ray structures of four R~S~( B I -~-C B~~H~) species have been determined (R3 = Et3, i-Pr3, t-Bu3, and t-BuzMe). Br6-CBllH6-is a particularly weakly coordinating anion and leads to long Si-Br bond distances (ca. 2.43-2.48 A). The developing silylium ion character in these species is reflected in the approach of the R3Si6+ moiety toward planarity. The sum of the C-Si-C angles for each of the four derivatives lies in the range ca. 345-351". The closest approach to 360" is found in the triisopropyl derivative, not the tri-tert-butyl derivative as might be anticipated from steric considerations. One of the isopropyl groups in the i-Pr3 derivative has its carbon atoms very nearly planar with the silicon atom. This is indicative of C-H bond hyperconjugative stabilization of the developing positive charge on silicon. An "inorganic" description would be in terms of a n a-agostic C-H interaction with the electron-deficient 3pz orbital on silicon. The results suggest that hyperconjugative stabilization of cationic character, although relatively unimportant compared to that for carbon in carbenium ions, is nevertheless not negligible for silicon. Solid state CPMAS 29Si NMR data are also reported. The chemical shifts lie in the 105-115 ppm downfield region as expected for silylium ion-like character in these R3sid+(Br6-cB~~H6)+ species. (14) Xie, Z.; Liston, D. J.; Jelinek, T.; Mitro, V.; Bau, R.; Reed, C. A. (15) Kira, M.; Hino, T.; Sakurai, H.

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Section: Resultsmentioning

confidence: 99%

The Silylium Ion (R3Si+) Problem: Effect of Alkyl Substituents R

Xie¹,

Bau²,

Benesi³

et al. 1995

Organometallics

102

141

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“…12 The C1-Br1-C8 bond angle of 103.9°i s considerably greater than that (98.2°) for the bissulfonyl iodonium ylide (CF 3 SO 2 ) 2 C --I + Ph. 13,14 This is probably due to the increased nonbonded repulsions between the two organic substituents on Br-(III) with a decreased atomic size. In addition to the intramolecular short Br1‚‚‚O1 contact, a nearly linear C8-Br1‚‚‚O2* (x -1/2, -y -1/2, z) secondary bonding to one of the sulfonyl oxygen atoms of an adjacent molecule was found with a Br‚‚‚O distance of 2.987-(2) Å, which links individual molecules of 2a into infinite zigzag chains (Figure S1).…”

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confidence: 99%

Synthesis and Characterization of Bromonium Ylides and Their Unusual Ligand Transfer Reactions with N-Heterocycles

et al. 2006

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Stable aliphatic bromonium ylides (RfSO2)2C--Br+C6H4-p-CF3 (Rf = CF3, CF3(CF2)3) have been synthesized and structurally characterized for the first time. X-ray crystallographic analyses indicated a ylide structure with an sp2 hybridization of the ylide carbanions and with little double-bond character for the ylidic bond. The bromonium ylides selectively undergo transfer of the aryl group to nitrogen heterocycles, such as pyridines, yielding N-arylpyridinium salts. This is in a marked contrast to the reaction of the iodonium ylides, which produces pyridinium ylides through transylidations.

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“…It is interesting to compare the role played by the bridging iodine in compound 5 with that of the bridging Br atom in [9, 5 In the latter compound the Br atom formally carries a positive charge and does not have an attached proton. The bromine cation contributes one electron to each C 2 B 10 H 11 fragment, effectively fulfilling the role of an exopolyhedral hydrogen for the borons to which the Br ϩ is attached.…”

Section: Resultsmentioning

confidence: 99%

Protonation reactions of the salts [Na][Pt(PR3)2(η5-7-CB10H11)] (PR3 = PEt3 or PMe2Ph): synthesis and crystal structures of the platinacarborane complexes [PtCl(PMe2Ph)2(η5-7-CB10H11)], [Pt2{μ-σ,η5∶σ′,η5′-8,9′-(7-CB10H10)2}(PMe2Ph)4] and [Pt2(PEt3)4{η5∶η5′-9,9′-I(H)(7-CB10H10)2}] †

Blandford¹,

Jeffery²,

Redfearn³

et al. 1998

J. Chem. Soc., Dalton Trans.

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Protonation of [Na][Pt(PMe 2 Ph) 2 (η 5 -7-CB 10 H 11 )] 1b with HCl in diethyl ether afforded a mixture of the complexes [PtX(PMe 2 Ph) 2 (η 5 -7-CB 10 H 11 )] (X = H 2b or Cl 3) and [Pt 2 {µ-σ,η 5 : σЈ,η 5 Ј-8,9Ј-(7-CB 10 H 10 ) 2 }(PMe 2 Ph) 4 ] 4. Singlecrystal X-ray diffraction studies established the structures of 3 and 4. In the former the platinum atom is coordinated on one side by the open CBBBB face of the nido-7-CB 10 H 11 cage and on the other by a chlorine atom and two PMe 2 Ph molecules. In the molecule 4 two nido-icosahedral CB 10 cage frameworks, each η 5 -co-ordinated by their open CBBBB faces to a platinum atom, are joined by a B᎐B connectivity and by two relatively long Pt᎐B connectivities.The B᎐B link is formed between a boron atom in a β site in one CBBBB ring and a boron in an α site in the other CBBBB ring. Each boron involved in this connectivity also forms a B᎐Pt linkage to the platinum atom in the adjacent closo-2,1-PtCB 10 sub-cluster. Thus the two metal atoms and the two borons form a 'butterfly' arrangement with the platinums at the wing-tips. Treatment of [Na][Pt(PEt 3 ) 2 (η 5 -7-CB 10 H 11 )] with HCl in diethyl ether gave [PtH(PEt 3 ) 2 (η 5 -7-CB 10 H 11 )] 2a as expected, but a complex mixture of other products was also formed. Addition of [NEt 4 ]I to this mixture allowed isolation of a species [Pt 2 (PEt 3 ) 4 {η 5 : η 5 Ј-9,9Ј-I(H)(7-CB 10 H 10 ) 2 }] 5. This unusual formulation is based principally on the results of an X-ray diffraction study which revealed that two icosahedral closo-2,1-PtCB 10 sub-clusters were bridged by an iodine atom.

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Crystal and molecular structure of bis-9-m-carboranylbromonium borofluoride

Cited by 5 publications

References 8 publications

The Silylium Ion (R3Si+) Problem: Effect of Alkyl Substituents R

The Silylium Ion (R3Si+) Problem: Effect of Alkyl Substituents R

Synthesis and Characterization of Bromonium Ylides and Their Unusual Ligand Transfer Reactions with N-Heterocycles

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