Chiral Octapalladium Chains Supported by Enantiopure P-Stereogenic Linear Tetraphosphines, (R,R)- and (S,S)-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2
Chiral Octapalladium Chains Supported by Enantiopure P-Stereogenic Linear Tetraphosphines, (R,R)- and (S,S)-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2
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由对映体纯 P-立体线性四膦 (R,R)- 和 (S,S)-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2 支持的手性八钯链
DOI：
10.1021/acs.inorgchem.0c03684
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发表时间：
2021
影响因子：
4.6
通讯作者：
Nakajima Takayuki
中科院分区：
文献类型：
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作者：
Tanase Tomoaki;Nakamae Kanako;Hayashi Suzui;Okue Ayumi;Otaki Risa;Nishida Tomoko;Ura Yasuyuki;Kitagawa Yasutaka;Nakajima Takayuki
rac-dpmppm负载的双核Pd（II）和Pt（II）配合物（双[（二苯基膦基甲基）苯基膦基]甲烷），为三氟桥Z-形式，[M2 Cl 4（rac-dpmppm）]（M = Pd（3a），Pt（3b）），在NH 4PF 6存在下容易地与2，6-二甲苯基异氰化物（XylNC）反应，得到[M2 Cl 2（rac-dpmppm）（XylNC）2]（PF_6）_2（M = Pd（4a），Pt（4 b）），其中每个金属中心在dpmppm的内P原子的转位处容纳一个异腈配体。类似地，用轴向手性（R/S）-1，1 ′-联萘-2，2 ′-二异氰化物处理3a和3b，（rac-Binac）在NH 4 OTf存在下得到环状四核配合物[{M2 Cl 2（rac-dpmppm）（外消旋-联乙酸）}2]（OTf）4（M = Pd（5），Pt（8）），其中两个{M2 Cl 2（rac-dpmpm）}2+片段通过（R*，R*）-dpmpm和（R*）-Binac的手性分选由tworac-Binac配体连接。配合物5可以转化为卤素交换的四核配合物[{Pd 2X2（rac-dpmppm）（rac-Binac）}2]（OTf）4（X = Br（6），I（7）），表明四个Pd（II）离子的矩形排列由于卤素配体之间的排斥作用而被拉长。利用（R）-和（S）-Binac，成功地分离出了对映体纯的Pd 4配合物[{Pd 2 Cl 2（（R*，R*）-dpmppm）（（R*）-Binac）}2]（OTf）4（5 RR/Rand 5SS/S），用NaCN水溶液处理后得到了对映体纯的（R，R）-和（S，S）-dpmppm。也就是说，通过四核Pd配合物建立了rac-dpmppm的光学拆分，这是亚甲基桥连多膦的第一个例子，R2 P（CH 2 PR）nCH 2 PR 2（n> 0）。此外，通过对映体纯的P-手性dpmppm与[Pd 2（CH 3CN）6]（BF 4）2和[Pd 2（dba）3]·C6 H6反应，合成了手性八钯链[Pd 8（（R*，R*）-dpmppm）4（N-CCH 3）2]（BF 4）4（2 RRand 2SS），并通过光谱和X-射线衍射对其进行了表征，确定了绝对构型. Pd 8链是迄今为止结构表征的最长的对映体纯手性单金属原子链，并在2 RR的DFT计算的基础上研究了其电子结构。
Binuclear Pd(II) and Pt(II) complexes supported byrac-dpmppm (bis[(diphenylphosphinomethyl)phenylphosphino]methane) in a triply-bridgedZ-form, [M2Cl4(rac-dpmppm)] (M = Pd (3a), Pt (3b)), readily reacted with 2,6-xylyl isocyanide (XylNC) in the presence of NH4PF6to afford [M2Cl2(rac-dpmppm)(XylNC)2](PF6)2(M = Pd (4a), Pt (4b)), in which each metal center accommodates one isocyanide ligand at thetransposition to the inner P atom of dpmppm. Similarly, treatment of3aand3bwith axially chiral (R/S)-1,1′-binaphthyl-2,2′-bisisocyanide (rac-Binac) in the presence of NH4OTf gave cyclic tetranuclear complexes, [{M2Cl2(rac-dpmppm)(rac-Binac)}2](OTf)4(M = Pd (5), Pt (8)), where two {M2Cl2(rac-dpmppm)}2+fragments are connected by tworac-Binac ligands through chirality sorting of (R*,R*)-dpmppm and (R*)-Binac. Complex5could be transformed into the halide exchanged tetranuclear complexes, [{Pd2X2(rac-dpmppm)(rac-Binac)}2](OTf)4(X = Br (6), I (7)), to show that the rectangular arrangement of four Pd(II) ions is elongated by repulsive interaction between halide ligands. By using (R)- and (S)-Binac, enantiopure Pd4complexes, [{Pd2Cl2((R*,R*)-dpmppm)((R*)-Binac)}2](OTf)4(5RR/Rand5SS/S), were successfully isolated as pure crystalline forms, from which enantiopure (R,R)- and (S,S)-dpmppm were obtained by treatment with NaCN aqueous solution. Namely, optical resolution ofrac-dpmppm was established through the tetranuclear Pd complexes, which is the first example for methylene-bridged polyphosphines, R2P(CH2PR)nCH2PR2(n> 0). Furthermore, chiral octapalladium chains, [Pd8((R*,R*)-dpmppm)4(N≡CCH3)2](BF4)4(2RRand2SS), were synthesized by reacting enantiopureP-chiral dpmppm with [Pd2(CH3CN)6](BF4)2and [Pd2(dba)3]·C6H6and were characterized by spectroscopic and X-ray crystallographic analyses, to determine the absolute configurational structures. The Pd8chains are the longest enantiopure chiral single-metal-atom chains structurally characterized, thus far, and the electronic structures were examined on the basis of DFT calculations of2RR.