TY - JOUR
T1 - Doubly pyridazine-bridged macrocyclic complexes of copper in + 1, + 2 and mixed valent oxidation states
AU - Brooker, Sally
AU - Davidson, Tony C.
AU - Hay, Sarah J.
AU - Kelly, Robert J.
AU - Kennepohl, Dietmar K.
AU - Plieger, Paul G.
AU - Moubaraki, Boujemaa
AU - Murray, Keith S.
AU - Bill, Eckhard
AU - Bothe, Eberhard
N1 - Funding Information:
We are grateful to B.M. Clark (University of Canterbury) for the FAB mass spectra, to Professor W.T. Robinson and Dr J. Wikaira (University of Canterbury) for the X-ray data collections, to N. Duffy (University of Otago) for helpful discussions and to M. Derrett, M. Pahl, W. Redmond (University of Otago) for their help. This research was supported in part by Public Good Science funding from the Foundation for Research, Science and Technology and the Marsden Fund, and by grants from the University of Otago and the Australian Research Council. SB thanks the University of Otago for the granting of study leave which allowed the spectroelectrochemical and EPR measurements to be carried out, and gratefully acknowledges her host Professor K. Wieghardt and the financial support of the Alexander von Humboldt Stiftung. SB is grateful for the award of a Bilateral Research Activities Programme Grant (International Science and Technology Linkages Fund) which enabled her to visit KSM. DKK thanks Athabasca University for granting study leave and financial support.
PY - 2001
Y1 - 2001
N2 - Transmetallation of the dilead(II) complex [Pb2(L1′)](ClO4)4 [L1′ is the (4 + 4) Schiff-base macrocycle derived from 3,6-diformylpyridazine and 1,3-diaminopropane] with copper(II) perchlorate results in the formation of a dicopper(II) complex of the (2 + 2) Schiff-base macrocycle L1, Cu2II(L1)(ClO4)4 (1). Copper(II) is unable to template the formation of 1 from the organic precursors. A series of six dicopper(II) complexes of L1 has been prepared from 1, including: [Cu2II(L1)X2](ClO4)2 (where X = Cl- 2, Br- 3, I- 4, NCS- 5), Cu2II(L1)(H2O)2(NO3) 2(ClO4)2 (6) and Cu2II(L1)(H2O)2(ClO4) 4 (7). Three of these dicopper(II) complexes, 1·2MeCN, 2·H2O and 7, have been characterised by X-ray crystallography. In all three cases the (2 + 2) macrocycle provides a double pyridazine bridge between the two copper(II) ions. Magnetic studies show that the double pyridazine bridge mediates strong antiferromagnetic exchange between the copper(II) ions in all of these complexes ( - 2J = 412 to 532 cm-1). Electrochemical and spectroelectrochemical studies reveal that reduction of the dicopper(II) complexes occurs in two one electron steps, via stable mixed valent intermediates (Kc = 3.8 × 105 to 8.6 × 106 in acetonitrile, MeCN), in marked contrast to all previously studied pyridazine-bridged dicopper complexes. The thiocyanate salt of the mixed valent complex, [CuIICuI(L1)(NCS)4CuI]MeCN (9), has been isolated, by transmetallation of [Pb2(L1′)](ClO4)4 with copper(I) followed by the addition of NaNCS, and structurally characterised. Finally, the previously reported grid complex, [Cu4I(L1)2](PF6)4 (10) [formed by templating L1 formation on copper(I) ions], is shown by NMR spectroscopy to exist in equilibrium with another species, presumed to be a dicopper(I) complex, [Cu2I(L1)(MeCN)2](PF6) 2 (11), in acetonitrile solution. In support of this assignment, the structure of the dicopper(I) complex, [Cu2I(L1)(PPh3)2](PF 6)2 (12), isolated from reaction of 10 with two equivalents of PPh3, is reported.
AB - Transmetallation of the dilead(II) complex [Pb2(L1′)](ClO4)4 [L1′ is the (4 + 4) Schiff-base macrocycle derived from 3,6-diformylpyridazine and 1,3-diaminopropane] with copper(II) perchlorate results in the formation of a dicopper(II) complex of the (2 + 2) Schiff-base macrocycle L1, Cu2II(L1)(ClO4)4 (1). Copper(II) is unable to template the formation of 1 from the organic precursors. A series of six dicopper(II) complexes of L1 has been prepared from 1, including: [Cu2II(L1)X2](ClO4)2 (where X = Cl- 2, Br- 3, I- 4, NCS- 5), Cu2II(L1)(H2O)2(NO3) 2(ClO4)2 (6) and Cu2II(L1)(H2O)2(ClO4) 4 (7). Three of these dicopper(II) complexes, 1·2MeCN, 2·H2O and 7, have been characterised by X-ray crystallography. In all three cases the (2 + 2) macrocycle provides a double pyridazine bridge between the two copper(II) ions. Magnetic studies show that the double pyridazine bridge mediates strong antiferromagnetic exchange between the copper(II) ions in all of these complexes ( - 2J = 412 to 532 cm-1). Electrochemical and spectroelectrochemical studies reveal that reduction of the dicopper(II) complexes occurs in two one electron steps, via stable mixed valent intermediates (Kc = 3.8 × 105 to 8.6 × 106 in acetonitrile, MeCN), in marked contrast to all previously studied pyridazine-bridged dicopper complexes. The thiocyanate salt of the mixed valent complex, [CuIICuI(L1)(NCS)4CuI]MeCN (9), has been isolated, by transmetallation of [Pb2(L1′)](ClO4)4 with copper(I) followed by the addition of NaNCS, and structurally characterised. Finally, the previously reported grid complex, [Cu4I(L1)2](PF6)4 (10) [formed by templating L1 formation on copper(I) ions], is shown by NMR spectroscopy to exist in equilibrium with another species, presumed to be a dicopper(I) complex, [Cu2I(L1)(MeCN)2](PF6) 2 (11), in acetonitrile solution. In support of this assignment, the structure of the dicopper(I) complex, [Cu2I(L1)(PPh3)2](PF 6)2 (12), isolated from reaction of 10 with two equivalents of PPh3, is reported.
KW - Copper
KW - Electrochemistry
KW - Macrocycle
KW - Mixed-valent
KW - Pyridazine
KW - X-ray crystal structure
UR - https://www.scopus.com/pages/publications/0012314723
U2 - 10.1016/S0010-8545(00)00399-4
DO - 10.1016/S0010-8545(00)00399-4
M3 - Review article
AN - SCOPUS:0012314723
SN - 0010-8545
VL - 216-217
SP - 3
EP - 30
JO - Coordination Chemistry Reviews
JF - Coordination Chemistry Reviews
ER -