Sterically Demanding 8-(Diphenylphosphino)quinoline Complexes of Group 10 Metal(II): Synthesis, Crystal Structures, and Properties in Solution
Sterically Demanding 8-(Diphenylphosphino)quinoline Complexes of Group 10 Metal(II): Synthesis, Crystal Structures, and Properties in Solution
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第 10 族金属 (II) 的空间要求 8-(二苯基膦)喹啉配合物：合成、晶体结构和溶液中的性质
DOI：
10.1021/acs.inorgchem.0c02706
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发表时间：
2020
影响因子：
4.6
通讯作者：
Suzuki Takayoshi
中科院分区：
文献类型：
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作者：
Mori Masatoshi;Sunatsuki Yukinari;Suzuki Takayoshi
合成了一系列含8-(二苯基膦)喹啉(PQH)及其2-甲基或2-苯基衍生物(PQMeor PQPh)的铂(II)、钯(II)、镍(II)配合物，研究了它们的晶体结构和溶液行为。本研究中表征的大多数配合物[M(PQR)2]X2(MII=PtII、PdII或NiII；R=H、Me或Ph；X=单阴离子)具有近似正方形的配位几何构型，在(P，P)构型中有两个双齿P，N-螯合或单齿P-供体的喹啉配体。在喹啉环的2位引入的Me或Ph取代基的大空间需求使所得的络合物严重扭曲。PtII和PdII络合阳离子保持了正方形-平面配位几何构型，但MII中心偏离了配位平面。这种络合配位的弯曲使M-N(喹啉)键变弱，如较长的M-N键所证明的那样。用UV-Vis光谱和X射线结晶学观察到PQH或PQMechelates被卤化物阴离子取代后的部分解离，与键的弱化相一致。相反，PQPh络合物在溶液中对卤化物阴离子的添加是稳定的；配位的喹啉基和2-取代苯环之间的分子内π-π堆积作用保护了MII中心免受亲核攻击。在相应的NiII络合物中，相互顺式定位的PQR配体引起的空间拥堵导致了NiII中心周围的大四面体扭曲。然而，分子内π-π堆积作用在PQPh络合物中仍然有效，这种相互作用可以解释NiII-PQPh络合物的一些特殊的稳健性和电化学性质。
Several series of platinum(II), palladium(II), and nickel(II) complexes bearing 8-(diphenylphosphino)quinoline (PQH) or its 2-methyl or 2-phenyl derivatives (PQMeor PQPh) were synthesized, and their crystal structures and behaviors in solution were investigated. Most of the complexes [M(PQR)2]X2(MII= PtII, PdII, or NiII; R = H, Me or Ph; X = monoanionic ions) characterized in this study have an approximately square-planar coordination geometry with two bidentateP,N-chelating or monodentateP-donating quinolylphosphine ligands in thecis(P,P) configuration. A large steric requirement from the Me or Ph substituent introduced at the 2-position of the quinoline ring gives the resulting complexes severe distortion. The PtIIand PdIIcomplex cations maintained the square-planar coordination geometry, but the MIIcenter was displaced from the chelating ligand plane. This bending of the chelate coordination makes the M–N(quinoline) bond weaker, as demonstrated by the longer M–N bonds. In accord with the bond weakening, the partial dissociation of the PQHor PQMechelates by substitution with halide anions were observed using UV–vis spectroscopy and X-ray crystallography. In contrast, the PQPhcomplexes were stable in solution toward the addition of halide anions; the intramolecular π–π stacking interaction between the coordinating quinolyl and the 2-substituted phenyl rings protects the MIIcenter from nucleophilic attack. In the corresponding NiIIcomplexes, the steric congestion arising from the mutuallycis-positioned PQRligands resulted in a large tetrahedral distortion around the NiIIcenter. However, the intramolecular π–π stacking interaction was still effective in the PQPhcomplex, and this interaction can explain some unusual robustness and electrochemical properties of the NiII–PQPhcomplex.