TY - JOUR
T1 - Tetranuclear nickel complexes composed of pairs of dinuclear LNi 2 fragments linked by 4,4′-bipyrazolyl, 1,4-bis(4′- pyrazolyl)benzene, and 4,4′-bipyridazine
T2 - Synthesis, structures, and magnetic properties
AU - Lozan, Vasile
AU - Solntsev, Pavlo Y.
AU - Leibeling, Guido
AU - Domasevitch, Konstantin V.
AU - Kersting, Berthold
PY - 2007
Y1 - 2007
N2 - The ability of the ligands 4,4′-bipyrazolyl (H2bpz), 1,4-bis(4′-pyrazolyl)benzene (H2bpzb), and 4,4′- bipyridazine (bpdz) to link two dioctahedral LNi2 units has been examined. The following complexes were prepared: [L1Ni II2(Hbpz)][BPh4] (6[BPh4]), [L 1NiII2(bpdz)][ClO4]2 (7[ClO4]2), [(L1NiII 2)2(bpzb)]-[BPh4]2 (8[BPh 4]2), and [(L2NiII2) 2(bpz)][BPh4]2 (9[BPh4] 2), where (L1)2- and (L2) 2- represent macrocychc hexaaza-dithiophenolate ligands. All complexes have been characterised by UV/Vis spectroscopy, IR spectroscopy, and X-ray crystallography. Whereas (Hbpz)- and bpdz in 6[BPh 4]2 and 7[ClO4]2 act as bidentate ligands coordinating to only one [LNi2]2+ unit, in 8[BPh4]2 and 9[BPh4]2 the (bpzb)2- and (bpz)2- units are tetradentate linkers. This is qualitatively explained in terms of the absence or presence of steric repulsions between the tBu groups of the supporting ligands and the length of the coligands. The structures of the tetranuclear complexes differ mainly in the distance between the center of the Ni⋯Ni axes of the isostructural [LNi2] units {14.040(1) Å in 8[BPh4]2, 9.184(1) Å in 9[BPh4]2}. The two Ni 2-pyrazolato planes in 9[BPh4]2 are coplanar. An analysis of the temperature-dependent magnetic susceptibility data for 9[BPh4]2 reveals the presence of weak ferromagnetic exchange interactions between the NiII ions in the binuclear [L 2Ni2] subunits with values for the magnetic exchange constant J1 of 23.97 cm-1 (H = -2JS1S 2). The exchange coupling across the dipyrazolato bridge is less than 0.1 cm-1, suggesting that no significant interdimer exchange coupling occurs in 9[BPh4]2.
AB - The ability of the ligands 4,4′-bipyrazolyl (H2bpz), 1,4-bis(4′-pyrazolyl)benzene (H2bpzb), and 4,4′- bipyridazine (bpdz) to link two dioctahedral LNi2 units has been examined. The following complexes were prepared: [L1Ni II2(Hbpz)][BPh4] (6[BPh4]), [L 1NiII2(bpdz)][ClO4]2 (7[ClO4]2), [(L1NiII 2)2(bpzb)]-[BPh4]2 (8[BPh 4]2), and [(L2NiII2) 2(bpz)][BPh4]2 (9[BPh4] 2), where (L1)2- and (L2) 2- represent macrocychc hexaaza-dithiophenolate ligands. All complexes have been characterised by UV/Vis spectroscopy, IR spectroscopy, and X-ray crystallography. Whereas (Hbpz)- and bpdz in 6[BPh 4]2 and 7[ClO4]2 act as bidentate ligands coordinating to only one [LNi2]2+ unit, in 8[BPh4]2 and 9[BPh4]2 the (bpzb)2- and (bpz)2- units are tetradentate linkers. This is qualitatively explained in terms of the absence or presence of steric repulsions between the tBu groups of the supporting ligands and the length of the coligands. The structures of the tetranuclear complexes differ mainly in the distance between the center of the Ni⋯Ni axes of the isostructural [LNi2] units {14.040(1) Å in 8[BPh4]2, 9.184(1) Å in 9[BPh4]2}. The two Ni 2-pyrazolato planes in 9[BPh4]2 are coplanar. An analysis of the temperature-dependent magnetic susceptibility data for 9[BPh4]2 reveals the presence of weak ferromagnetic exchange interactions between the NiII ions in the binuclear [L 2Ni2] subunits with values for the magnetic exchange constant J1 of 23.97 cm-1 (H = -2JS1S 2). The exchange coupling across the dipyrazolato bridge is less than 0.1 cm-1, suggesting that no significant interdimer exchange coupling occurs in 9[BPh4]2.
KW - Bipyrazolate ligands
KW - Macrocyclic ligands
KW - Magnetic properties
KW - Nickel
KW - Polynuclear complexes
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U2 - 10.1002/ejic.200700317
DO - 10.1002/ejic.200700317
M3 - Article
AN - SCOPUS:34547166940
SN - 1434-1948
SP - 3217
EP - 3226
JO - European Journal of Inorganic Chemistry
JF - European Journal of Inorganic Chemistry
IS - 20
ER -