Syntheses, crystal structures and magnetic properties of dinuclear copper(II) complexes with pyrazino[2,3-f ][4,7]phenanthroline (pap) as bridging ligand
作者:Hilde Grove、Jorunn Sletten、Miguel Julve、Francesc Lloret
DOI:10.1039/a907658a
日期:——
Three dinuclear copper(II) complexes with pyrazino[2,3-f][4,7]phenanthroline (pap) as bridging ligand have been prepared; [Cu2(pap)(C2O4)2]·5H2O 1, [Cu2(pap)(H2O)7(SO4)]SO4·3H2O 2 and [Cu2(pap)(H2O)3(NO3)3]NO33. These are the first metal complexes of pap which have been characterized by X-ray crystallography and magnetic susceptibility measurements. In 1 the dinuclear complex is intercepted by a mirror plane; the bridging pap and the terminal oxalate ligands are bidentate in the equatorial plane of copper. In addition copper has weak axial interactions to oxygen atoms of oxalate in two neighbouring molecules. In 2 the two crystallograpically independent copper atoms are both six-co-ordinated with bridging pap and water molecules in equatorial positions, the axial positions being occupied by two water molecules or one water molecule and one sulfate oxygen atom, respectively. In 3 the co-ordination geometry of one copper is close to square pyramidal with pap, one nitrate oxygen atom and one water in equatorial positions; another water occupies the apical position. The description of the co-ordination sphere of the other copper is complicated by the presence of disorder in one of the co-ordinated nitrate groups. When considering only the major site of the disordered nitrate, the co-ordination geometry may in a first approximation be described as square pyramidal with a significant trigonal bipyramidal distortion. In the square pyramidal description the two pap nitrogen atoms, one water and one nitrate oxygen constitute the equatorial plane and a nitrate oxygen is situated in apical position. All the co-ordinated nitrate ions have a second weak Cu⋯O interaction. The Cu⋯Cu separations across bridging pap are 6.740 (1), 6.834 (2) and 6.808 Å (3). Variable-temperature susceptibility measurements reveal Curie law behaviour with very weak intramolecular antiferromagnetic coupling in all three compounds, the relevant parameters being J = −1.4 cm−1, g = 2.06 for 1, J = −1.5 cm−1, g = 2.10 for 2, and J = −1.3 cm−1, g = 2.08 for 3 (the Hamiltonian being H = −J SA·SB).
准备了三种二核铜(II)配合物,使用呫唑并[2,3-f][4,7]菲啰啉(pap)作为桥联配体;分别为[Cu2(pap)(C2O4)2]·5H2O 1、[Cu2(pap)(H2O)7(SO4)]SO4·3H2O 2 和 [Cu2(pap)(H2O)3(NO3)3]NO3。这些是首次通过X射线晶体学和磁化率测量表征的pap金属配合物。在1中,二核配合物被一个镜面平面截断;桥联的pap和末端的草酸配体在铜的赤道平面内是双齿配体。此外,铜还与两个相邻分子的草酸的氧原子存在弱的轴向相互作用。在2中,两种晶体独立的铜原子都被六个配位,桥联的pap和水分子处于赤道位置,轴向位置分别被两个水分子或一个水分子及一个硫酸根氧原子占据。在3中,一个铜的配位几何形状接近于正方体金字塔,配体为pap、一个硝酸根氧原子和一个水分子位于赤道位置;另一个水分子位于顶点位置。另一个铜的配位球的描述因一个配位的硝酸根配体的无序出现而变得复杂。当仅考虑无序硝酸根的主要位点时,配位几何形状可以在初步近似下描述为正方体金字塔,并存在显著的三角双金字塔畸变。在正方体金字塔的描述中,两个pap氮原子、一个水分子和一个硝酸根氧原子构成赤道平面,一个硝酸根氧原子位于顶点位置。所有配位的硝酸根离子都有第二个弱的Cu⋯O相互作用。通过桥联pap的Cu⋯Cu间隔分别为6.740 Å (1)、6.834 Å (2) 和6.808 Å (3)。可变温的磁化率测量揭示出符合居里定律的行为,在三种化合物中,分子内的抗铁磁耦合非常弱,相关参数为1中J = −1.4 cm−1,g = 2.06;2中J = −1.5 cm−1,g = 2.10;3中J = −1.3 cm−1,g = 2.08(哈密顿量为H = −J SA·SB)。