Slagt Martijn Q, Rodríguez Gema, Grutters Michiel M P, Klein Gebbink Robertus J M, Klopper Wim, Jenneskens Leonardus W, Lutz Martin, Spek Anthony L, van Koten Gerard
Debye Institute, Department of Metal-Mediated Synthesis, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Chemistry. 2004 Mar 19;10(6):1331-44. doi: 10.1002/chem.200305336.
A variety of para-substituted NCN-pincer palladium(II) and platinum(II) complexes [MX(NCN-Z)] (M=Pd(II), Pt(II); X=Cl, Br, I; NCN-Z=2,6-(CH(2)NMe(2))(2)C(6)H(2)-4-Z; Z=NO(2), COOH, SO(3)H, PO(OEt)(2), PO(OH)(OEt), PO(OH)(2), CH(2)OH, SMe, NH(2)) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water-soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by (195)Pt NMR spectroscopy and DFT calculations. Both the (195)Pt chemical shift and the calculated natural population charge on platinum correlate linearly with the sigma(p) Hammett substituent constants, and thus the electronic properties of predesigned pincer complexes can be predicted. The sigma(p) value for the para-PtI group itself was determined to be -1.18 in methanol and -0.72 in water/methanol (1/1). Complexes substituted with protic functional groups (CH(2)OH, COOH) exist as dimers in the solid state due to intermolecular hydrogen-bonding interactions.
通过涉及取代反应的路线合成了多种对位取代的 NCN 钳形钯（II）和铂（II）配合物[MX(NCN-Z)]（M = Pd(II)，Pt(II)；X = Cl、Br、I；NCN-Z = 2,6-(CH(2)NMe(2))(2)C(6)H(2)-4-Z；Z = NO(2)、COOH、SO(3)H、PO(OEt)(2)、PO(OH)(OEt)、PO(OH)(2)、CH(2)OH、SMe、NH(2)），这些反应可以在配体金属化之前进行，或者尤其在配体金属化之后进行。钳形配合物的溶解度主要由对位取代基 Z 的性质决定，这使得几种配合物具有水溶性。通过（195）Pt NMR 光谱和 DFT 计算研究了对位取代基对金属中心电子性质的影响。（195）Pt 化学位移和计算得到的铂上的自然布居电荷都与 σ(p) Hammett 取代基常数呈线性相关，因此可以预测预先设计的钳形配合物的电子性质。在甲醇中，对位 -PtI 基团本身的 σ(p) 值测定为 -1.18，在水/甲醇（1/1）中为 -0.72。由于分子间氢键相互作用，被质子官能团（CH(2)OH、COOH）取代的配合物在固态时以二聚体形式存在。
