TY - JOUR
T1 - Synthesis, crystal structure and magnetic properties of a novel nitroxide biradical. Theoretical investigation of the exchange mechanisms
AU - Fritscher, J.
AU - Beyer, Mario
AU - Schiemann, Olav
N1 - Funding Information:
This work was financially supported by the DFG. J. F. gratefully acknowledges the Fonds der Chemischen Industrie for a Chemiefondsstipendium für Doktoranden and O. S. the DFG for a Habilitandenstipendium. Thanks to B. Wolf for the SQUID measurements, M. Bolte for the X-ray measurements and to I. Ciofini for the helpful discussion. The authors also thank T. F. Prisner for his support.
PY - 2002/10/4
Y1 - 2002/10/4
N2 - The novel nitroxide biradical 1,8-bis(3-ethinyl-2,2,5,5-tetramethyl-3-pyrroline-1-oxyl)-naphthalene was synthesized and its structure and magnetic properties were investigated. Using SQUID measurements an antiferromagnetic exchange coupling of 2J = -3.5 K was evaluated. Temperature-dependent measurements of the half-field EPR signal intensity and broken symmetry DFT computations confirm this result. To unravel the mechanisms of the intramolecular exchange interaction calculations on model systems were performed. These revealed a strong ferromagnetic through-bond interaction via the 1,8-substituted naphthalene bridge and a competing strong antiferromagnetic through-space interaction via the acetylene groups. Both interactions are of the same order of magnitude leading to the weak overall coupling observed.
AB - The novel nitroxide biradical 1,8-bis(3-ethinyl-2,2,5,5-tetramethyl-3-pyrroline-1-oxyl)-naphthalene was synthesized and its structure and magnetic properties were investigated. Using SQUID measurements an antiferromagnetic exchange coupling of 2J = -3.5 K was evaluated. Temperature-dependent measurements of the half-field EPR signal intensity and broken symmetry DFT computations confirm this result. To unravel the mechanisms of the intramolecular exchange interaction calculations on model systems were performed. These revealed a strong ferromagnetic through-bond interaction via the 1,8-substituted naphthalene bridge and a competing strong antiferromagnetic through-space interaction via the acetylene groups. Both interactions are of the same order of magnitude leading to the weak overall coupling observed.
UR - http://www.scopus.com/inward/record.url?scp=0037020139&partnerID=8YFLogxK
U2 - 10.1016/S0009-2614(02)01344-1
DO - 10.1016/S0009-2614(02)01344-1
M3 - Article
AN - SCOPUS:0037020139
SN - 0009-2614
VL - 364
SP - 393
EP - 401
JO - Chemical Physics Letters
JF - Chemical Physics Letters
IS - 3-4
ER -