A pincer ligand composed of a pyridine with ortho positions substituted by a bulky phosphine arm and a pyrazole arm (PNNH) is installed on nickel(II) to yield the diamagnetic planar complex [(PNNH)NiCl]Cl. The chloride anion can be replaced by BPh₄⁻ by a metathesis. The acidic pyrazole proton can be removed with LiN(SiMe₃)₂ to yield the square planar neutral molecule (PNN⁻)NiCl. The coordinated chloride can be metathetically replaced by azide to yield diamagnetic (PNN⁻)Ni(N₃). To evaluate changing the phosphine donor for a phosphine sulfide, the corresponding pincer ligand SPNNH was synthesized and installed on NiBr₂. The reduced steric bulk from the more distant phosphorous keeps both halides coordinated in the paramagnetic molecular species (SPNNH)NiBr₂. Several attempts to dehydrobrominate this species result in synthesis and characterization of two unexpected products. One effort revealed that the electrophilic character of P(V) leaves the phosphorus atom in (SPNNH)NiBr₂ vulnerable to nucleophilic attack, resulting in a P/C cleavage product which was characterized.

中文翻译：

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具有不同供体的钳子及其相互转化：在 Ni(II) 上的应用

由邻位吡啶组成的钳形配体被庞大的膦臂和吡唑臂 (PNNH) 取代，安装在镍 (II) 上以产生抗磁性平面配合物 [(PNNH)NiCl]Cl。氯阴离子可以通过复分解被BPh ₄ ^-代替。酸性吡唑质子可以用 LiN(SiMe ₃ ) ₂去除以产生方形平面中性分子 (PNN ^- )NiCl。配位的氯化物可以被叠氮化物置换以产生抗磁性 (PNN ^- )Ni(N ₃ )。为了评估将膦供体改变为硫化膦，合成了相应的钳状配体 SPNNH 并将其安装在 NiBr _{2 上}. 来自更远的磷的减少的空间体积使两种卤化物在顺磁性分子种类 (SPNNH)NiBr _{2 中}保持协调。对该物质进行脱溴化氢的几次尝试导致了两种意想不到的产物的合成和表征。一项研究表明，P(V) 的亲电特性使 (SPNNH)NiBr _{2 中}的磷原子容易受到亲核攻击，从而产生了一种已表征的 P/C 裂解产物。