Departamento de Química Inorgánica, Universidad de Granada, Av. Fuentenueva S/N, 18071, Granada, Spain.
Dalton Trans. 2009 Nov 21(43):9578-86. doi: 10.1039/b910811d. Epub 2009 Sep 23.
Eight new complexes containing the versatile multidentate ligand 5-pyrimidyl-tetrazolate (pmtz), namely Cu(mu(3)-pmtz) (1), [Pd(2)(mu-pmtz)(2)Cl(2)] (2), [Ni(pmtz)(en)(2)]Cl x 2 H(2)O (3), [Cu(tren)(pmtz)(ClO(4))] (4), Co(2)(tren)(2)(mu-pmtz)(mu-O(2))(3) x 3 H(2)O (5), [Fe(2)(pmtz)(4)(H(2)O)(2)(mu-O)] x 5 H(2)O (6), [(UO(2))(4)(mu-pmtz)(2)(mu-OH)(2)(mu(3)-O)(2)(H(2)O)(4)] x 6 H(2)O (7) and Dy(2)(pmtz)(4)(mu-pmtz)(H(2)O)(6) x 6 H(2)O (8), have been prepared by either conventional solution or hydrothermal techniques and characterised by single-crystal X-ray diffraction. Those compounds prepared under hydrothermal conditions ((1), (2), (7) and (8)) exhibit chelating/bridging coordination modes that connect two or three metal ions generating polynuclear species. Thus, compound is a 2D polymer where the ligand exhibits a new chelating/bridging kappa(2)N(1),N(7):kappaN(2):kappaN(3) coordination mode, whereas complexes (2) and (7) are dinuclear and tetranuclear species, respectively, in which the ligand displays a kappa(2)N(1),N(7):kappaN(2) coordination mode. The increase of the metal size favours the adoption of the kappa(2)N(1),N(7):kappa(2)N(4),N(11) bis(chelating)bridging mode. This is the case of compound (8) that contains bulky Dy(III) metal ions. Despite the large size of the UO(2+) metal ion, the pmtz ligand in (7) does not adopt the expected bis(chelating)bridging mode because the uranyl cation hydrolyzes to the highly stable bis(mu(3)-oxo) tetranuclear unit. Conventional mild solution conditions lead to complexes containing monodentate or chelating coordination modes. Thus, compounds (3) and (6) are mononuclear and mu-oxo dinuclear species, respectively, which contain kappa(2)N(1),N(7) chelating pmtz ligands. Compound (4) is mononuclear with the ligand acting in a new monodentate form through the N(1) atom of the tetrazolato ring, whereas (5) is a dinuclear complex where pmtz adopts a new exo-bidentate N(2),N(3) bridging coordination mode. Variable-temperature magnetic measurements of (6) indicate that the oxo-bridge mediates a very strong antiferromagnetic interaction between the iron(III) ions with a J = -222.7 cm(-1). Luminescence measurements show that the pmtz ligands act as "antenna" for energy absorption and transfer to the uranyl emissive state.
八种新的配合物含有多功能多齿配体 5-嘧啶基四唑（pmtz），即 Cu(mu(3)-pmtz)（1）、[Pd(2)(mu-pmtz)(2)Cl(2)]（2）、[Ni(pmtz)(en)(2)]Cl x 2 H(2)O（3）、[Cu(tren)(pmtz)(ClO(4))]（4）、Co(2)(tren)(2)(mu-pmtz)(mu-O(2))(3) x 3 H(2)O（5）、[Fe(2)(pmtz)(4)(H(2)O)(2)(mu-O)] x 5 H(2)O（6）、[(UO(2))(4)(mu-pmtz)(2)(mu-OH)(2)(mu(3)-O)(2)(H(2)O)(4)] x 6 H(2)O（7）和 Dy(2)(pmtz)(4)(mu-pmtz)(H(2)O)(6) x 6 H(2)O（8），通过常规溶液或水热技术制备，并通过单晶 X 射线衍射进行了表征。那些在水热条件下制备的化合物（1）、（2）、（7）和（8）表现出螯合/桥联配位模式，连接两个或三个金属离子生成多核物种。因此，化合物是二维聚合物，其中配体表现出新的螯合/桥联 kappa(2)N(1)、N(7)：kappaN(2)：kappaN(3)配位模式，而配合物（2）和（7）分别是双核和四核物种，其中配体显示 kappa(2)N(1)、N(7)：kappaN(2)配位模式。金属尺寸的增加有利于采用 kappa(2)N(1)、N(7)：kappa(2)N(4)、N(11)双（螯合）桥联模式。这就是包含大体积 Dy(III)金属离子的化合物（8）的情况。尽管 UO(2+)金属离子的尺寸很大，但 pmtz 配体在（7）中不采用预期的双（螯合）桥联模式，因为铀酰阳离子水解成高度稳定的双（μ-氧）四核单元。常规温和的溶液条件导致含有单齿或螯合配位模式的配合物。因此，化合物（3）和（6）分别是单核和 mu-氧双核物种，它们含有 kappa(2)N(1)、N(7)螯合的 pmtz 配体。化合物（4）是单核的，配体通过四唑环的 N(1)原子以新的单齿形式作用，而（5）是双核配合物，其中 pmtz 采用新的外双齿 N(2)、N(3)桥联配位模式。（6）的变温磁性测量表明，氧桥介导了铁（III）离子之间非常强的反铁磁相互作用，J = -222.7 cm(-1)。荧光测量表明，pmtz 配体充当“天线”，用于吸收能量并将能量转移到铀的发射态。
