Santana M Dolores, García Gabriel, Lozano A Abel, López Gregorio, Tudela José, Pérez José, García Luis, Lezama Luis, Rojo Teófilo
Departamento de Química Inorgánica, Universidad de Murcia, 30071 Murcia, Spain.
Chemistry. 2004 Apr 2;10(7):1738-46. doi: 10.1002/chem.200305367.
The bis(phosphatediester)-bridged complexes [Ni([12]aneN(3))(mu-O(2)P(OR)(2))](PF(6))(2) [[12]aneN(3)=Me(3)[12]aneN(3), 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene; R=Me (1), Bu (2), Ph (3), Ph-4-NO(2) (4); [12]aneN(3)=Me(4)[12]aneN(3), 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene; R=Me (5), Bu (6), Ph (7), Ph-4-NO(2) (8)] were prepared by hydrolysis of the phosphate triester with the hydroxo complex [Ni([12]aneN(3))(mu-OH)](PF(6))(2) or by acid-base reaction of the dialkyl or diaryl phosphoric acid and the above hydroxo complex. The acid-base reaction was also used to synthesise the phosphinate-bridged complexes [Ni([12]aneN(3))(mu-O(2)PR(2))](PF(6))(2) [[12]aneN(3)=Me(3)[12]aneN(3), R=Me (9), Ph (10); [12]aneN(3)=Me(4)[12]aneN(3), R=Me (11), Ph (12)]. The molecular structures of complexes 2, 3 and 12 were established by single crystal X-ray diffraction studies. The eight-membered rings defined by the nickel atoms and the bridging ligands show distorted twist-boat, chair and boat-boat conformations in 2, 3 and 12, respectively. The experimental susceptibility data for compounds 2, 3 and 12 were fitted by least-squares methods to the analytical expression given by Ginsberg. The best fit was obtained with values of J=-0.11 cm(-1), D=-9.5 cm(-1) and g=2.20 for 2; J=-0.97 cm(-1), D=-9.3 cm(-1) and g=2.21 for 3; and J=-0.14 cm(-1), D=-11.9 cm(-1) and g=2.195 for 12. The magnetic-exchange pathways must involve the phosphate/phosphinate bridges, because these favour antiferromagnetic interactions. The observation of a higher exchange parameter for compound 3 is a consequence of a favourable disposition of the O-P-O bridges. The kinetics for the hydrolysis of TNP (tris(4-nitrophenyl)phosphate) with the dinuclear nickel(II) hydroxo complex [Ni(Me(3)[12]aneN(3))(mu-OH)](PF(6))(2) was studied by UV-visible spectroscopy. The proposed mechanism for TNP-promoted hydrolysis can be described as one-substrate/two-product, and can be fitted to a Michaelis-Menten equation.
双（磷酸二酯）桥联配合物[Ni([12]aneN(3))(μ - O(2)P(OR)(2))](PF(6))(2) [[12]aneN(3)=Me(3)[12]aneN(3)，即2,4,4 - 三甲基 - 1,5,9 - 三氮杂环十二 - 1 - 烯；R = Me（1），Bu（2），Ph（3），Ph - 4 - NO(2)（4）；[12]aneN(3)=Me(4)[12]aneN(3)，即2,4,4,9 - 四甲基 - 1,5,9 - 三氮杂环十二 - 1 - 烯；R = Me（5），Bu（6），Ph（7），Ph - 4 - NO(2)（8）]通过磷酸三酯与羟基配合物[Ni([12]aneN(3))(μ - OH)](PF(6))(2)水解制备，或通过二烷基或二芳基磷酸与上述羟基配合物的酸碱反应制备。酸碱反应还用于合成次膦酸酯桥联配合物[Ni([12]aneN(3))(μ - O(2)PR(2))](PF(6))(2) [[12]aneN(3)=Me(3)[12]aneN(3)，R = Me（9），Ph（10）；[12]aneN(3)=Me(4)[12]aneN(3)，R = Me（11），Ph（12）]。配合物2、3和12的分子结构通过单晶X射线衍射研究确定。由镍原子和桥联配体定义的八元环在2、3和12中分别呈现扭曲的扭船型、椅型和船 - 船型构象。化合物2、3和12的实验磁化率数据通过最小二乘法拟合到金斯伯格给出的解析表达式。对于2，最佳拟合得到J = - 0.11 cm(-1)，D = - 9.5 cm(-1)，g = 2.20；对于3，J = - 0.97 cm(-1)，D = - 9.3 cm(-1)，g = 2.21；对于12，J = - 0.14 cm(-1)，D = - 11.9 cm(-1)，g = 2.195。磁交换途径必定涉及磷酸酯/次膦酸酯桥，因为这些有利于反铁磁相互作用。化合物3具有较高交换参数的观察结果是O - P - O桥有利排列的结果。通过紫外 - 可见光谱研究了双核镍（II）羟基配合物[Ni(Me(3)[12]aneN(3))(μ - OH)](PF(6))(2)与TNP（三（4 - 硝基苯基）磷酸酯）水解的动力学。所提出的TNP促进水解的机制可描述为单底物/双产物，并且可以拟合到米氏方程。
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