Chmielewski Piotr J., Latos-Grazynski Lechoslaw
Department of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw, Poland.
Inorg Chem. 1998 Aug 24;37(17):4179-4183. doi: 10.1021/ic971387i.
Addition of aryl Grignard reagents [PhMgCl, PhMgBr, (Ph-d(5))MgBr, (o-MePh)MgBr, (m-MePh)MgBr] dissolved in ethyl ether or THF to toluene solutions of nickel(II) dihalide complexes of 5,10,15,20-tetraphenyl-21,23-dioxaporphyrin (O(2)TPP), 1, at 203 K resulted in formation of a variety of rare paramagnetic sigma-organonickel(II) species that have been detected and subsequently characterized by (1)H and (2)H NMR. The stoichiometry and the spectral pattern of the formed complexes depend strongly on the counteranion present in the Grignard reagent. Titration of PhMgCl to 1-Cl (203 K) led to the substitution of only one chloride ligand by the phenyl anion, yielding (O(2)TPP)Ni(II)(Ph)Cl (2). The coordination of a sigma-phenyl ligand has been proven by the downfield pattern of two observed phenyl resonances at 243K (129.20 (m), 63.71 ppm (p)) accompanied by downfield furan (31.53 ppm) and pyrrole (25.85 ppm) resonances of equatorial O(2)TPP. Titration with PhMgBr resulted in formation of the different monophenyl adduct (O(2)TPP)Ni(II)(Ph)Br (3) and the first paramagnetic organonickel(II) complex with two sigma-aryl ligands, i.e., the bisphenyl adduct (O(2)TPP)Ni(II)(Ph)(2) (4). Both 3 and 4 have revealed the (1)H NMR upfield-shifted patterns with no parallel to any nickel(II) porphyrin or heteroporphyrin (3, -165.21 ppm (pyrr), -54.49 ppm (f); 4, -143.05 ppm (pyrr), -31.35 ppm (f), 243 K). The ortho, meta, and para proton resonances of 3 are located in the typical low-field region (558 ppm (o), 153.46 ppm (m), 71.58 ppm (p) at 243 K). In contrast, the phenyl signals of 4 have been detected in the strikingly narrow region (8 to -10 ppm). An interpretation of this spin delocalization requires a change of the nickel(II) ion ground state from (d(xy)())(2)(d(xz)())(2)(d(yz)())(2)(d(z)()()2)(1)(d(x)()()2(-)()(y)()()2)(1) determined for 2 to (d(xy)())(2)(d(x)()()2(-)()(y)()()2)(2)(d(yz)())(2)(d(z)()()2)(1)(d(xz)())(1) and (d(xy)())(2)(d(x)()()2(-)()(y)()()2)(2)(d(z)()()2)(2)(d(yz)())(1)(d(xz)())(1) configurations for 3 and 4, respectively. Warming of 2, 3, or 4 resulted in their decomposition to produce the sigma-phenylnickel(I) 21,23-dioxaporphyrin (O(2)TPP)Ni(I)(Ph) 6 identified by EPR studies (g(1)( )()= 2.411; g(2) = 2.161; g(3) = 2.049). This species has been also generated by an independent route reacting (O(2)TPP)Ni(I)Br with the Grignard reagent.
将溶解于乙醚或四氢呋喃中的芳基格氏试剂[苯基氯化镁、苯基溴化镁、(苯基 - d(5))溴化镁、(邻甲基苯基)溴化镁、(间甲基苯基)溴化镁]添加到5,10,15,20 - 四苯基 - 21,23 - 二氧杂卟啉（O₂TPP）镍（II）二卤化物配合物1的甲苯溶液中，于203K下反应，生成了多种罕见的顺磁σ - 有机镍（II）物种，这些物种已通过¹H和²H核磁共振检测并随后进行了表征。所形成配合物的化学计量比和光谱模式强烈依赖于格氏试剂中存在的抗衡阴离子。将苯基氯化镁滴定至1 - Cl（203K），仅导致一个氯配体被苯基阴离子取代，生成（O₂TPP）Ni（II）（Ph）Cl（2）。在243K时观察到的两个苯基共振的低场模式（129.20（m），63.71ppm（p））以及赤道O₂TPP的呋喃（31.53ppm）和吡咯（25.85ppm）共振的低场位移，证明了σ - 苯基配体的配位。用苯基溴化镁滴定导致形成不同的单苯基加合物（O₂TPP）Ni（II）（Ph）Br（3）以及首个具有两个σ - 芳基配体的顺磁有机镍（II）配合物，即双苯基加合物（O₂TPP）Ni（II）（Ph）₂（4）。3和4都显示出¹H NMR高场位移模式，这与任何镍（II）卟啉或杂卟啉均不相同（3，-165.21ppm（吡咯），-54.49ppm（呋喃）；4，-143.05ppm（吡咯），-31.35ppm（呋喃），243K）。3的邻、间、对质子共振位于典型的低场区域（243K时为558ppm（o），153.46ppm（m），71.58ppm（p））。相比之下，4的苯基信号在非常窄的区域（8至 - 10ppm）被检测到。这种自旋离域的解释需要镍（II）离子基态从为（2）所确定的（d(xy)²(d(xz)²(d(yz)²(d(z²)¹(d(x² - y²)¹)转变为分别为3和4的（d(xy)²(d(x² - y²)²(d(yz)²(d(z²)¹(d(xz)¹)和（d(xy)²(d(x² - y²)²(d(z²)²(d(yz)¹(d(xz)¹)构型。将2、3或4加热导致它们分解，生成通过电子顺磁共振研究鉴定的σ - 苯基镍（I）21,23 - 二氧杂卟啉（O₂TPP）Ni（I）（Ph）6（g(1) = 2.411；g(2) = 2.161；g(3) = 2.049）。该物种也通过（O₂TPP）Ni（I）Br与格氏试剂的独立反应路线生成。
