Oxidative Addition of an Aromatic ortho C-H bond of Tetraphosphine to Asymmetric Diiridium(I) Centers
Oxidative Addition of an Aromatic ortho C-H bond of Tetraphosphine to Asymmetric Diiridium(I) Centers
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四膦芳香族邻位 C-H 键与不对称二铱 (I) 中心的氧化加成
DOI：
10.1039/c5dt04725k
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
T.
中科院分区：
文献类型：
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作者：
Nakajima;T.; Noda;S.; Sakamoto;M.; Matsui;A.; Nakamae;K.; Kure;B.; Ura;Y.; Tanase;T.
四膦，meso-bis{[（二苯基膦基甲基）苯基]膦基}丙烷（dpmpp）与[IrCl（cod）]2和CO（1atm）或异氰化物（RNC）在NH 4PF 6存在下在80-100 ℃在二氯甲烷/乙腈/丙酮和/或甲醇混合溶剂中反应，得到不对称二铱（II）配合物，[Ir 2（H）（Cl）（μ-（dpmpp-H）-κ P4 C）（CO）3] PF 6（1）和[Ir 2（H）（μ-（dpmpp-H）-κ P4 C）（RNC）4）]-（PF 6）2（R = 2，6-二甲苯基（2）、2，4，6-均三甲苯基（3）; dpmpp-H = {PPh（o-C6 H4）CH 2 P（Ph）（CH 2）3 P（Ph）CH 2 PPh 2}−）。与tBuNC的类似反应导致形成[Ir（H）（dpmpp-κP3）（tBuNC）2]（PF 6）2（4）的单核IrIII络合物。配合物1-3通过ESI质谱、1H和31 P NMR谱和X射线衍射分析进行了表征。发现它们由dpmpp的邻位C-H键氧化加成得到的cis/trans-P，P不对称IrII-IrII键合双核结构（Ir-Ir = 2.8044（2）<$（1），2.8569（2）<$（2），2.8524（5）<$（3）），形成[IrPCClr]金属间环桥和末端氢化物。DFT计算表明存在Ir-Ir、Ir-H和Ir-Cortho共价键。在室温下与CO和XylNC的反应的初始阶段通过31 P {1H} NMR光谱进行研究，发现包含具有dpmpp的对称IrI双核单元，其在加热时容易转化为1和2。IrI 2与XylNC的中间体[Ir 2（XylNC）4（μ-dpmpp）]（PF 6）2（6）被分离出来，并通过X射线晶体学和DFT计算表征为缺电子32 e − IrI 2物种，涉及IrI→IrI配价键（2.7989（5）π）。通过密度泛函理论计算研究了从6到2的反应途径。本研究表明，一个新的邻位C-H键的氧化加成进行cis/trans-P，P不对称的双铱（I）支架的四膦，dpmpp，这被认为是由双金属合作切换Ir→Ir配价相互作用促进。
Reactions of a tetraphosphine, meso-bis{[(diphenylphosphinomethyl)phenyl]phosphino}propane (dpmppp), with [IrCl(cod)]2 and CO (1 atm) or isocyanide (RNC) in the presence of NH4PF6 at 80–100 °C in dichloromethane/acetonitrile/acetone and/or methanol mixed solvents afforded asymmetric diiridium(II) complexes, [Ir2(H)(Cl)(μ-(dpmppp-H)-κP4C)(CO)3]PF6 (1) and [Ir2(H)(μ-(dpmppp-H)-κP4C)(RNC)4)]-(PF6)2 (R = 2,6-xylyl (2), 2,4,6-mesityl (3); dpmppp-H = {PPh(o-C6H4)CH2P(Ph)(CH2)3P(Ph)CH2PPh2}−). A similar reaction with tBuNC resulted in the formation of a mononuclear IrIII complex of [Ir(H)(dpmppp-κP3)(tBuNC)2](PF6)2 (4). Complexes 1–3 were characterized by ESI mass spectrometry, 1H and 31P NMR spectroscopy and X-ray diffraction analyses. They were found to consist of cis/trans-P,P asymmetric IrII–IrII bonded dinuclear structures derived from oxidative addition of an ortho C–H bond of dpmppp (Ir–Ir = 2.8044(2) Å (1), 2.8569(2) Å (2), and 2.8524(5) Å (3)), resulting in a [IrPCCIr] intermetallic cyclometal-bridge and a terminal hydride. DFT calculations indicated the presence of Ir–Ir, Ir–H, and Ir–Cortho covalent bonds. Initial stages of the reactions with CO and XylNC at room temperature were investigated by 31P{1H} NMR spectroscopy and found to contain a symmetrical IrI dinuclear unit with dpmppp that was readily transformed into 1 and 2 upon heating. The IrI2 intermediate with XylNC, [Ir2(XylNC)4(μ-dpmppp)](PF6)2 (6), was isolated and characterized by X-ray crystallography and DFT calculations as an electron-deficient 32e− IrI2 species involving a IrI→IrI dative bond (2.7989(5) Å). The reaction pathways from 6 to 2 were investigated by DFT calculations. The present study suggested that a novel oxidative addition of an ortho C–H bond proceeded on the cis/trans-P,P asymmetric diiridium(I) scaffold supported by the tetraphosphine, dpmppp, which was assumed to be facilitated by dimetal cooperation with switching Ir→Ir dative interactions.