Manganese and Rhenium Formyl Complexes of Diphosphanylborane Ligands: Stabilization of the Formyl Unit from Intramolecular B–O Bond Formation
Manganese and Rhenium Formyl Complexes of Diphosphanylborane Ligands: Stabilization of the Formyl Unit from Intramolecular B–O Bond Formation
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二膦基硼烷配体的锰和铼甲酰基配合物：通过分子内 B-O 键形成来稳定甲酰基单元
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发表时间：
2013
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影响因子：
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通讯作者：
H. Berke
中科院分区：
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作者：
Rajkumar Jana;S. Chakraborty;O. Blacque;H. Berke
制备了几种锰(I)和铼(I)羰基配合物的螯合二磷酸基硼烷配体Ph2PCH(PPh2)CH2B(C8H14)(1)和Ph2PCH2CH[B(C8H14)]PPh2(2)，研究了路易斯酸辅助CO的化学计量还原。通过Mn(CO)5Br或Re(CO)5Br与二磷酸基硼烷配体1和2的反应，得到了顺式Mn(CO)3(1)(Br) （3a）、fac、顺式Re(CO)3(1)(Br) （4a）、fac、顺式Mn(CO)3(2)(Br) （5a）和fac、顺式Re(CO)3(2)(Br) （6a）配合物。在黑暗中，用一等量AgBF4在CH2Cl2中进一步处理这四种配合物，然后用1atm的CO进行处理，得到相应的单离子配合物[Mn(CO)4(1)][BF4] (3b), [Re(CO)4(1)][BF4] (4b), [Mn(CO)4(2)][BF4] （5b）和[Re(CO)4(2)](BF4) [6b]。x射线衍射研究证实了3b的预期分子结构。除了核磁共振和元素分析表征外，这些配合物的结构可以根据两个主要的ν(CO) IR波段进行明确的分配，从而建立了顺式（CO）4局部配体环境。阳离子配合物3b、4b、5b和6b在氯苯中与NaHBEt3反应，进行了CO还原的化学计量学测试。然而，配合物3b和4b的还原产生甲酰和氢化物的混合物。配合物5b和6b反应生成稳定的甲酰基衍生物[Mn(CHO)(CO)3(2)] （5c）和[Re(CHO)(CO)3(2)] (6c)，并对其进行了分离纯化和光谱表征。此外，通过单晶x射线表征，揭示了5c的甲酰基结构和与甲酰基氧原子的Lewis酸B（C8H14）基团的稳定配位。
Several manganese(I) and rhenium(I) carbonyl complexes of the chelating diphosphanylborane ligands Ph2PCH(PPh2)CH2B(C8H14) (1) and Ph2PCH2CH[B(C8H14)]PPh2 (2) were prepared to study Lewis acid assisted stoichiometric CO reductions. The phosphanylborane complexes fac,cis-Mn(CO)3(1)(Br) (3a), fac,cis-Re(CO)3(1)(Br) (4a), fac,cis-Mn(CO)3(2)(Br) (5a), and fac,cis-Re(CO)3(2)(Br) (6a) were obtained from the reactions of Mn(CO)5Br or Re(CO)5Br with diphosphanylborane ligands 1 and 2. Further treatment of all four complexes with one equivalent of AgBF4 in CH2Cl2 in the dark followed by 1 atm of CO afforded the corresponding monocationic complexes [Mn(CO)4(1)][BF4] (3b), [Re(CO)4(1)][BF4] (4b), [Mn(CO)4(2)][BF4] (5b), and [Re(CO)4(2)](BF4) [6b]. An X-ray diffraction study confirmed the expected molecular structure of 3b. In addition to NMR and elemental analysis characterizations, the structures of these complexes could be unambiguously assigned based on two major ν(CO) IR bands, which established the cis-(CO)4 local ligand environment. The cationic complexes 3b, 4b, 5b, and 6b were tested for stoichiometric CO reductions by reaction with NaHBEt3 in chlorobenzene. However, the reductions of the complexes 3b and 4b produced mixtures of formyl and hydride species. The reaction of complexes 5b and 6b led to the formation of the stable formyl derivatives [Mn(CHO)(CO)3(2)] (5c) and [Re(CHO)(CO)3(2)] (6c), which were isolated in pure form and characterized by spectroscopic means. In addition, 5c could be characterized by a single-crystal X-ray study, which revealed the formyl structure and a stabilizing coordination of the pendant Lewis acidic B(C8H14) group to the formyl oxygen atom.