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首页> 外文期刊>Organometallics >PNP-Pincer Complexes of Osmium: Comparison with Isoelectronic (PCP)Ir and (PNP)Ir+ Units
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PNP-Pincer Complexes of Osmium: Comparison with Isoelectronic (PCP)Ir and (PNP)Ir+ Units

机译：锇的PNP-PINCER复合物：与异电子（PCP）IR和（PNP）IR + 单位进行比较

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摘要

Several complexes of (~( t Bu_(4))PNP)Os ( 1 ) (~( t Bu_(4))PNP = C_(5)NH_(3)-2,6-(CH_(2)P~( t )Bu_(2))_(2)) are reported. 1 is isoelectronic with (~( t Bu_(4))PCP)Ir ( 2 ), which has played a leading role in homogeneous catalytic alkane dehydrogenation; the (~( t Bu_(4))PNP)Os complexes were investigated in this context. (~( t Bu_(4))PNP)OsH_(4) ( 1-H _( 4 )) is analogous to (~( t Bu_(4))PCP)IrH_(4) ( 2-H _( 4 )), but while 2-H _( 4 ) has some character of a dihydrogen dihydride, 1-H _( 4 ) is unambiguously a tetrahydride. Ethylene reacts with 1-H _( 4 ) to afford trans -(~( t Bu_(4))PNP)OsH_(2)(C_(2)H_(4)) ( 1-H _( 2 ) (C _( 2 ) H _( 4 ) ) ). At 25 °C, 1-H _( 2 ) (C _( 2 ) H _( 4 ) ) readily undergoes reversible ethylene insertion into an Os–H bond to yield (~( t Bu_(4))PNP)OsH(C_(2)H_(5)) ( 1-EtH ). DFT calculations indicate that alkane C–H addition to 1 is thermodynamically much more favorable than addition to 2 . The favorable thermodynamics of 1-(alkyl)H , however, disfavor reductive elimination and formation of the free Os(0) fragment that is required for a catalytic cycle analogous to that reported for 2 . The much greater favorability of C–H or H–H addition to 1 as compared with Ir(I) fragment 2 would typically be attributed to the lower oxidation state of 1 . However, H_(2) addition to the perfectly isoelectronic [(~( t Bu_(4))PNP)Ir(I)]~(+) cation is even more favorable than addition to 1 ; thus the thermodynamic differences result from the difference of the pincer ligand (PNP vs PCP) rather than the different metal centers (Os(0) vs Ir(I)). Although H_(2) addition to Ir(I) is as favorable as addition to Os(0), addition of a second molecule of H_(2) (to give tetrahydrides) is much more favorable for (~( t Bu_(4))PNP)Os. NBO analysis indicates that the MH_(2)/MH_(4) additions are oxidative, whereas the M/MH_(2) transformations are reductive.
机译：（〜（t bu_（4））pnp）OS（1）（〜（t bu_（4））pnp = c_（5）nh_（3）-2,6-（ch_（2）p〜（报告了T）BU_（2））_（2））。 1是等电子与（〜（4））PCP）IR（2），其在均匀催化烷烃脱氢中发挥了主要作用;在这种情况下研究了（〜（t bu_（4））pnp）OS复合物。 （〜（t bu_（4））pnp）osh_（4）（1-h _（4））类似于（〜（t bu_（4））pcp）irh_（4）（2-h _（4） ）但是，虽然2-H _（4）具有二氢氢化二氢氢化物的一些特征，但是1-H _（4）是明确的四氢。乙烯与1-H _（4）反应，得到反式 - （〜（t bu_（4））pnp）ω（2）（c_（2）h_（4））（1-h _（2）（c _ （2）H _（4））））。在25℃，1-H _（2）（C _（2）H _（4））方面容易地经历可逆乙烯插入OS-H键，得到（〜（t bu_（4））pnp）osh（ C_（2）H_（5））（1-Eth）。 DFT计算表明，烷烃C-H除了2的热力学上比添加到2的比例更加有利。然而，1-（烷基）H的有利热力学，然而，不适应的还原消除和形成催化循环类似于2的催化循环所需的可用OS（0）片段。与IR（I）片段2相比，C-H或H-H除了1的更大的优势通常归因于1的氧化态。但是，H_（2）除了完美的等电子[（〜（t bu_（4））pnp）Ir（i）]〜（+）阳离子比添加到1更好;因此，热力学差异是由钳子配体（PNP与PCP）而不是不同金属中心的差异（OS（0）Vs IR（i））。尽管H_（2）添加IR（I）与OS（0）的除外一样有利，但添加第二分子的H_（2）（得到四氢甲酸乙片）更有利（〜（t bu_（4） ）PNP）OS。 NBO分析表明MH_（2）/ MH_（4）添加是氧化的，而M / MH_（2）变换是还原的。

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  • 来源
    《Organometallics》 |2018年第3期|共13页
  • 作者

    Nicholas Lease; Elizabeth M. Pelczar; Tian Zhou; Santanu Malakar; Thomas J. Emge; Faraj Hasanayn; Karsten Krogh-Jespersen; Alan S. Goldman;

  • 作者单位

    Department of Chemistry and Chemical Biology Rutgers The State University of New Jersey 610 Taylor Road Piscataway New Jersey 08855 United States;

    Department of Chemistry and Chemical Biology Rutgers The State University of New Jersey 610 Taylor Road Piscataway New Jersey 08855 United States;

    Department of Chemistry and Chemical Biology Rutgers The State University of New Jersey 610 Taylor Road Piscataway New Jersey 08855 United States;

    Department of Chemistry and Chemical Biology Rutgers The State University of New Jersey 610 Taylor Road Piscataway New Jersey 08855 United States;

    Department of Chemistry and Chemical Biology Rutgers The State University of New Jersey 610 Taylor Road Piscataway New Jersey 08855 United States;

    Department of Chemistry The American University of Beirut Beirut 1107 2020 Lebanon;

    Department of Chemistry and Chemical Biology Rutgers The State University of New Jersey 610 Taylor Road Piscataway New Jersey 08855 United States;

    Department of Chemistry and Chemical Biology Rutgers The State University of New Jersey 610 Taylor Road Piscataway New Jersey 08855 United States;

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