Tris(pyrazolyl)phosphine Oxides. Synthesis and Coordination Chemistry with Copper(I)

A set of substituted tris­(pyrazolyl)­phosphine oxides (OP­(pzx)3) has been prepared in high yield and applied as neutral scorpion-type ligands. The P apex provides a convenient spectroscopic handle. Substitution at the 3-position of the pyrazolyl ring influences the steric demands of the ligand, while substitution at the 5-position enhances the stability. Copper­(I) acetonitrile complexes of the OP­(pzx)3 ligands were prepared and tested in ligand exchange reactions with PPh3 and CO. The ν­(CO) values of the carbonyl complexes demonstrate the electron-withdrawing properties of the ligands. These observations show that OP­(pzx)3 ligands are an interesting extension of the widely used scorpion-type ligands.

一系列取代三(吡唑基)氧化膦（tris(pyrazolyl)phosphine oxides，OP(pzx)3）以高产率合成，并被用作中性蝎型配体。该类配体的磷原子顶点为其提供了便捷的光谱表征位点。吡唑环3位的取代基会影响配体的空间位阻需求，而5位取代则可提升配体的稳定性。我们制备了OP(pzx)3配体的铜(I)乙腈配合物，并对其与PPh3及CO的配体交换反应进行了测试。羰基配合物的ν(CO)（羰基伸缩振动波数）数值证实了该类配体的吸电子特性。上述研究结果表明，OP(pzx)3配体是当前广泛应用的蝎型配体的一类极具研究价值的拓展体系。