Structure and magnetism of dinuclear copper(II) metallacyclophanes with oligoacenebis(oxamate) bridging ligands: theoretical predictions on wirelike magnetic coupling.
Self-assembly of the ligands N,N'-1,5-naphthalenebis(oxamate) (1,5-naba) and N,N'-2,6'-anthracenebis(oxamate) (2,6-anba) by Cu(II) ions affords the two new dicopper(II) metallacyclophanes 2a and 3b, whereby the metal centers are connected by double naphthalene- and anthracenediamidate bridges with alpha,alpha' and beta,beta' substitution patterns, respectively. Despite the largely different intermetallic distances of 8.3 A (2a) and 12.3 A (3b), magnetic susceptibility measurements show a moderately strong antiferromagnetic coupling with rather similar J values in the range from -20.5 to -20.7 (2a) and from -21.2 to -23.0 (3b) cm(-1) (H = -J S1 x S2; S1 = S2 = 1/2). Density functional theory calculations on the two series of dicopper(II) metallacyclophanes 1a-10a and 1b-10b with linear alpha,alpha'- and beta,beta'-disubstituted oligoacenediamidate bridges, respectively, confirm the better efficiency of the latter substitution pattern on long-range magnetic coupling. More importantly, they predict a unprecedented wirelike magnetic behavior for the longest members of the series with octacene through decacene spacers (J values up to +3.0 cm(-1) for intermetallic distances reaching 28.8 A).
Pardo
Emilio
E
Departament de Química Inorgànica, Instituto de Ciencia Molecular, Universitat de València, Paterna, València, E-46980 Spain.
Carrasco
Rosa
R
Ruiz-García
Rafael
R
Julve
Miguel
M
Lloret
Francesc
F
Muñoz
M Carmen
MC
Journaux
Yves
Y
Ruiz
Eliseo
E
Cano
Joan
J
D000873:Anthracenes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004988:Ethers, Cyclic / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D008280:Magnetics; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010072:Oxamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry
D000873:Anthracenes; D004988:Ethers, Cyclic; D008024:Ligands; C526837:N,N'-1,5-naphthalenebis(oxamate); C526840:N,N'-2,6'-anthracenebis(oxamate); D009281:Naphthalenes; D009942:Organometallic Compounds; D003300:Copper; D010072:Oxamic Acid