Alkyl-substituted Schlenk hydrocarbon diradicals with triplet and singlet ground states in frozen solutions

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Abstract

Ground states for alkyl-substituted Schlenk hydrocarbon diradicals 1-4 in frozen 2-MeTHF or THF are determined at low temperatures by EPR spectroscopy (4-80 K) or SQUID magnetometry (2-80 K). Diradicals 1, 2, and 3 are triplet ground states. Diradical 4 is the singlet ground state with the singlet-triplet gap, ΔEST ≈ -0.2 kcal mol-1. Another minor diradical present in the samples of 4 possesses ΔEST ≈ -0.02 kcal mol-1; most likely, this diradical corresponds to another conformational isomer of 4. Compound 4 is the first hydrocarbon diradical with antiferromagnetic coupling through 1,3-phenylene, a ubiquitous mediator of a ferromagnetic coupling.

Original languageEnglish (US)
Pages (from-to)1077-1082
Number of pages6
JournalJournal of the Chemical Society. Perkin Transactions 2
Issue number5
DOIs
StatePublished - Jan 1 1998

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Hydrocarbons
Ground state
SQUIDs
Isomers
Paramagnetic resonance
Spectroscopy
Temperature

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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abstract = "Ground states for alkyl-substituted Schlenk hydrocarbon diradicals 1-4 in frozen 2-MeTHF or THF are determined at low temperatures by EPR spectroscopy (4-80 K) or SQUID magnetometry (2-80 K). Diradicals 1, 2, and 3 are triplet ground states. Diradical 4 is the singlet ground state with the singlet-triplet gap, ΔEST ≈ -0.2 kcal mol-1. Another minor diradical present in the samples of 4 possesses ΔEST ≈ -0.02 kcal mol-1; most likely, this diradical corresponds to another conformational isomer of 4. Compound 4 is the first hydrocarbon diradical with antiferromagnetic coupling through 1,3-phenylene, a ubiquitous mediator of a ferromagnetic coupling.",
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T1 - Alkyl-substituted Schlenk hydrocarbon diradicals with triplet and singlet ground states in frozen solutions

AU - Rajca, Andrzej

AU - Rajca, Suchada

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N2 - Ground states for alkyl-substituted Schlenk hydrocarbon diradicals 1-4 in frozen 2-MeTHF or THF are determined at low temperatures by EPR spectroscopy (4-80 K) or SQUID magnetometry (2-80 K). Diradicals 1, 2, and 3 are triplet ground states. Diradical 4 is the singlet ground state with the singlet-triplet gap, ΔEST ≈ -0.2 kcal mol-1. Another minor diradical present in the samples of 4 possesses ΔEST ≈ -0.02 kcal mol-1; most likely, this diradical corresponds to another conformational isomer of 4. Compound 4 is the first hydrocarbon diradical with antiferromagnetic coupling through 1,3-phenylene, a ubiquitous mediator of a ferromagnetic coupling.

AB - Ground states for alkyl-substituted Schlenk hydrocarbon diradicals 1-4 in frozen 2-MeTHF or THF are determined at low temperatures by EPR spectroscopy (4-80 K) or SQUID magnetometry (2-80 K). Diradicals 1, 2, and 3 are triplet ground states. Diradical 4 is the singlet ground state with the singlet-triplet gap, ΔEST ≈ -0.2 kcal mol-1. Another minor diradical present in the samples of 4 possesses ΔEST ≈ -0.02 kcal mol-1; most likely, this diradical corresponds to another conformational isomer of 4. Compound 4 is the first hydrocarbon diradical with antiferromagnetic coupling through 1,3-phenylene, a ubiquitous mediator of a ferromagnetic coupling.

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