Structure and Reactivity of Organopalladium Complexes Bearing Unusual Oxidation State of Pd

本课题的目的是：1)合成一些具有形式氧化态Pd（i)或Pd（IV）的有机钯配合物，2）阐明其分子和电子结构，3)探索这些结构的一些反应性特征。获得的主要发现如下。1)通过Pd（IV）络合物进行转化，在烯丙基框架的2位含有氯甲基的pi -烯丙基络合物，[Pd(CH_2C(CH_2Cl)CH_2)(C_5H_5)]通过Pd(IV)-金属循环[Pd(CH_2C(CH_2G_5H_5)CH_2)Cl] ^+形成C-C键。除了C_5H_5配体外，[Pd(CH_2C(CH_2CL)CH_2)SPh]的SPh基团也可以通过Pd（IV）中间体进行类似的转化，生成[Pd(CH_2C(CH_2SPh)CH_2)CI]。2) Pd(I)配合物的合成与结构利用Pd(0)与Pd（II）之间的偶联，以丁二烯为模板剂，提出了合成Pd(I)-Pd(I)双核配合物的一般方法。因此，在Pd(II) （Cl, Br， I）和二烯配体上使用一些配体可以选择性地合成阴离子的[Pd_2X_3（二烯）]、中性的[Pd_2X_2(PPh_3)（二烯）]和阳离子的[Pd_2X(PPh_3)_2（二烯）]^+双核配合物。x射线结构测定证实了s-反式桥接二烯配体。这样配位的二烯配体包括阴离子二烯醇酯。在[Pd_2(PPh_3) _2(diene) _2] ^<2+>中发现了异常长的Pd-Pd距离（3.19 A），远高于之前报道的Pd-Pd长度（-2.83 A）。MO计算表明，这种拉长的Pd-Pd长度归因于Pd-Pd键向二烯LUMO的电子密度的反向捐赠。不寻常的双钯配合物与乙腈或乙炔反应生成。分别释放两个或一个二烯分子。

The aim of this project is i) to synthesize a number of organopalladium complexes having a formal oxidation state of Pd(I) or Pd(IV), ii) to elucidate their molecular and electronic structures, and iii) to explore some reactivities characteristic of such structures.The principal findings obtained follow.1) Transformations proceeding through Pd(IV) complexesPI-Allyl complex containing the chloromethyl group at 2-position of the allyl framework, [Pd(CH_2C(CH_2Cl)CH_2)(C_5H_5)] afforded C-C bond formation product, [Pd(CH_2C(CH_2G_5H_5)CH_2)Cl] via a Pd(IV)-metallacycle [Pd(CH_2C(=CH_2)CH_2)(C_5H_5)] ^+. Other than the C_5H_5 ligand, the SPh group of [Pd(CH_2C(CH_2CL)CH_2)SPh] also enabled an analogous transformation via the Pd(IV) intermediate, giving rise to [Pd(CH_2C(CH_2SPh)CH_2)CI].2) Synthesis and structure of Pd(I) complexesA general method of synthesizing Pd(I)-Pd(I) dinuclear complexes has been developed by making use of coupling between Pd(0) and Pd(II) species with butadiene playing a template role. Thus, employing some ligands on Pd(II) (Cl, Br, I) and diene ligands led to selective synthesis of anionic, [Pd_2X_3(diene)], neutral, [Pd_2X_2(PPh_3)(diene)], and cationic, [Pd_2X(PPh_3)_2(diene)] ^+ dinuclear complexes. X-Ray structure determinations confirmed the s-trans bridging diene ligand. The diene ligands so coordinating included anionic dienolate. The structure determination also revealed unusually long Pd-Pd distance (3.19 A) in [Pd_2(PPh_3) _2(diene) _2] ^<2+>, a value much longer than the previously reported Pd-Pd length (-2.83 A). MO calculations indicated that such elongated Pd-Pd length is attributed to back donation of electron densities from the Pd-Pd bond to LUMO of the diene. The unusual dicationic dipalladium complex reacted with acetonitrile or acetylene to result. in liberation of two or one diene molecule, respectively.