Facile electrophilic iodination of icosahedral carboranes. Synthesis of carborane derivatives with boron - Carbon bonds via the palladium-catalyzed reaction of diiodocarboranes with grignard reagents

Zhiping Zheng, Wei Jiang, Alfred A. Zinn, Carolyn B. Knobler, M. Frederick Hawthorne

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Abstract

Electrophilic diiodination reactions of icosahedral closo-1,2-C2B10H12 and closo-1,7-C2B10H12 using 2 molar equiv of iodine monochloride in the presence of catalytic amounts of aluminum chloride yielded the corresponding closo-9,12-I2-1,2-C2B10H10 and closo-9,10-I2-1,7-C2B10H10 complexes in excellent yields. Palladium-mediated cross-coupling reactions of these diiodocarboranes with a variety of alkyl, aralkyl, and aryl Grignard reagents were reinvestigated, and it was demonstrated that the addition of copper(I) iodide as a cocatalyst is crucial to the success of this reaction. A reaction mechanism involving the initial formation of binary organocopper species (RCu; R = alkyl, aralkyl, aryl) followed by the reaction of (σ-carboranyl)palladium iodides (L2Pd(CbI)I and L2Pd(CbR)I; L = PPh3, Cb = closo-1,2-C2B10H10, closo-1,7-C2B10H10) via a four-centered transition state is proposed. The molecular structures of closo-9,10-I2-1,7-C2B10H10, 1, and closo-9,10-(C6H5)2-1,7-C2B 10H10, 10, have been determined. Crystallographic data are as follows: for 1, monoclinic, space group P21/c, a = 13.2719-(6) Å, b = 14.9718(6) Å, c = 13.4734(6) Å, β = 114.211(1)°, V = 2441.7(3) Å3, Z = 8, ρcalcd = 2.15 g cm-3, R = 0.043, Rw = 0.064; for 10, tetragonal, space group I41/a, a = 9.446(2) Å, c = 39.949(8) Å, V = 3564.1(1) Å3, Z = 8, ρcalcd = 1.10 g cm-3, R = 0.056, Rw = 0.063.

Original languageEnglish (US)
Pages (from-to)2095-2100
Number of pages6
JournalInorganic Chemistry
Volume34
Issue number8
StatePublished - 1995
Externally publishedYes

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carborane
Boron
Palladium
reagents
palladium
boron
Carbon
Derivatives
carbon
Iodides
synthesis
Molecular structure
iodides
aluminum chlorides
cross coupling
iodine
molecular structure
copper
iodine monochloride
cuprous iodide

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Facile electrophilic iodination of icosahedral carboranes. Synthesis of carborane derivatives with boron - Carbon bonds via the palladium-catalyzed reaction of diiodocarboranes with grignard reagents. / Zheng, Zhiping; Jiang, Wei; Zinn, Alfred A.; Knobler, Carolyn B.; Hawthorne, M. Frederick.

In: Inorganic Chemistry, Vol. 34, No. 8, 1995, p. 2095-2100.

Research output: Contribution to journalArticle

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title = "Facile electrophilic iodination of icosahedral carboranes. Synthesis of carborane derivatives with boron - Carbon bonds via the palladium-catalyzed reaction of diiodocarboranes with grignard reagents",
abstract = "Electrophilic diiodination reactions of icosahedral closo-1,2-C2B10H12 and closo-1,7-C2B10H12 using 2 molar equiv of iodine monochloride in the presence of catalytic amounts of aluminum chloride yielded the corresponding closo-9,12-I2-1,2-C2B10H10 and closo-9,10-I2-1,7-C2B10H10 complexes in excellent yields. Palladium-mediated cross-coupling reactions of these diiodocarboranes with a variety of alkyl, aralkyl, and aryl Grignard reagents were reinvestigated, and it was demonstrated that the addition of copper(I) iodide as a cocatalyst is crucial to the success of this reaction. A reaction mechanism involving the initial formation of binary organocopper species (RCu; R = alkyl, aralkyl, aryl) followed by the reaction of (σ-carboranyl)palladium iodides (L2Pd(CbI)I and L2Pd(CbR)I; L = PPh3, Cb = closo-1,2-C2B10H10, closo-1,7-C2B10H10) via a four-centered transition state is proposed. The molecular structures of closo-9,10-I2-1,7-C2B10H10, 1, and closo-9,10-(C6H5)2-1,7-C2B 10H10, 10, have been determined. Crystallographic data are as follows: for 1, monoclinic, space group P21/c, a = 13.2719-(6) {\AA}, b = 14.9718(6) {\AA}, c = 13.4734(6) {\AA}, β = 114.211(1)°, V = 2441.7(3) {\AA}3, Z = 8, ρcalcd = 2.15 g cm-3, R = 0.043, Rw = 0.064; for 10, tetragonal, space group I41/a, a = 9.446(2) {\AA}, c = 39.949(8) {\AA}, V = 3564.1(1) {\AA}3, Z = 8, ρcalcd = 1.10 g cm-3, R = 0.056, Rw = 0.063.",
author = "Zhiping Zheng and Wei Jiang and Zinn, {Alfred A.} and Knobler, {Carolyn B.} and Hawthorne, {M. Frederick}",
year = "1995",
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number = "8",

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TY - JOUR

T1 - Facile electrophilic iodination of icosahedral carboranes. Synthesis of carborane derivatives with boron - Carbon bonds via the palladium-catalyzed reaction of diiodocarboranes with grignard reagents

AU - Zheng, Zhiping

AU - Jiang, Wei

AU - Zinn, Alfred A.

AU - Knobler, Carolyn B.

AU - Hawthorne, M. Frederick

PY - 1995

Y1 - 1995

N2 - Electrophilic diiodination reactions of icosahedral closo-1,2-C2B10H12 and closo-1,7-C2B10H12 using 2 molar equiv of iodine monochloride in the presence of catalytic amounts of aluminum chloride yielded the corresponding closo-9,12-I2-1,2-C2B10H10 and closo-9,10-I2-1,7-C2B10H10 complexes in excellent yields. Palladium-mediated cross-coupling reactions of these diiodocarboranes with a variety of alkyl, aralkyl, and aryl Grignard reagents were reinvestigated, and it was demonstrated that the addition of copper(I) iodide as a cocatalyst is crucial to the success of this reaction. A reaction mechanism involving the initial formation of binary organocopper species (RCu; R = alkyl, aralkyl, aryl) followed by the reaction of (σ-carboranyl)palladium iodides (L2Pd(CbI)I and L2Pd(CbR)I; L = PPh3, Cb = closo-1,2-C2B10H10, closo-1,7-C2B10H10) via a four-centered transition state is proposed. The molecular structures of closo-9,10-I2-1,7-C2B10H10, 1, and closo-9,10-(C6H5)2-1,7-C2B 10H10, 10, have been determined. Crystallographic data are as follows: for 1, monoclinic, space group P21/c, a = 13.2719-(6) Å, b = 14.9718(6) Å, c = 13.4734(6) Å, β = 114.211(1)°, V = 2441.7(3) Å3, Z = 8, ρcalcd = 2.15 g cm-3, R = 0.043, Rw = 0.064; for 10, tetragonal, space group I41/a, a = 9.446(2) Å, c = 39.949(8) Å, V = 3564.1(1) Å3, Z = 8, ρcalcd = 1.10 g cm-3, R = 0.056, Rw = 0.063.

AB - Electrophilic diiodination reactions of icosahedral closo-1,2-C2B10H12 and closo-1,7-C2B10H12 using 2 molar equiv of iodine monochloride in the presence of catalytic amounts of aluminum chloride yielded the corresponding closo-9,12-I2-1,2-C2B10H10 and closo-9,10-I2-1,7-C2B10H10 complexes in excellent yields. Palladium-mediated cross-coupling reactions of these diiodocarboranes with a variety of alkyl, aralkyl, and aryl Grignard reagents were reinvestigated, and it was demonstrated that the addition of copper(I) iodide as a cocatalyst is crucial to the success of this reaction. A reaction mechanism involving the initial formation of binary organocopper species (RCu; R = alkyl, aralkyl, aryl) followed by the reaction of (σ-carboranyl)palladium iodides (L2Pd(CbI)I and L2Pd(CbR)I; L = PPh3, Cb = closo-1,2-C2B10H10, closo-1,7-C2B10H10) via a four-centered transition state is proposed. The molecular structures of closo-9,10-I2-1,7-C2B10H10, 1, and closo-9,10-(C6H5)2-1,7-C2B 10H10, 10, have been determined. Crystallographic data are as follows: for 1, monoclinic, space group P21/c, a = 13.2719-(6) Å, b = 14.9718(6) Å, c = 13.4734(6) Å, β = 114.211(1)°, V = 2441.7(3) Å3, Z = 8, ρcalcd = 2.15 g cm-3, R = 0.043, Rw = 0.064; for 10, tetragonal, space group I41/a, a = 9.446(2) Å, c = 39.949(8) Å, V = 3564.1(1) Å3, Z = 8, ρcalcd = 1.10 g cm-3, R = 0.056, Rw = 0.063.

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