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首页> 外文期刊>Chemistry: A European journal >Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium
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Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium

机译：铑和铱的末端和桥接母体氨基1,5-环辛二烯络合物

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摘要

The ready availability of rare parent amido d~8 complexes of the type [{M(μ-NH_2)(cod)}_2] (M=Rh (1), Ir (2); cod=1,5-cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di-olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [{M(μ-NH_2)(CO)_2}_2] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH_2Cl _2 or CHCl_3, giving the diiridium(II) products [(Cl)(cod)Ir(μ-NH_2)_2Ir(cod)(R)] (R=CH_2Cl or CHCl_2) as a result of a two-center oxidative addition and concomitant metal-metal bond formation. However, reaction with ClCH_2CH _2Cl afforded the symmetrical adduct [{Ir(μ-NH_2)(Cl) (cod)}_2] upon release of ethylene. We found that the rhodium complex 1 exchanged the di-olefines stepwise upon addition of selected phosphanes (PPh_3, PMePh_2, PMe_2Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ-NH_2)_2Rh(PR_3) _2], and finally the isolation of the respective tetraphosphanes [{Rh(μ-NH_2)(PR_3)_2}_2]. On the other hand, the iridium complex 2 reacted with PMe_2Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH_2)(PMePh_2)_2]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh_2)_2]. The heterocyclic carbene IPr (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) also split the amido bridges in complexes 1 and 2, allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH _2)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs _2CO_3, finding that the iridium complex 2 is more active than the rhodium analogue 1. Tight connection: The reactivity and relative strength of NH_2 bridges in cyclooctadiene (cod) complexes of Rh and Ir of the type [{M(μ-NH_2)(cod)}_2] have been tested with a variety of donors. In general they are tightly bound to the metals. With the diiridium complex and selected ligands, the formation of terminal [Ir(d ~8)-NH_2] species were observed (see scheme).
机译：通过[{M（μ-NH_2）（cod）} _ 2]（M = Rh（1），Ir（2）; cod = 1,5-环辛二烯）类型的稀有母体氨基d〜8复合物的随时可用直接使用气态氨可以研究其反应性。配合物1和2都通过一氧化碳交换二烯烃，得到双核四羰基衍生物[{M（μ-NH_2）（CO）_2} _2]（M ＝ Rh或Ir）。二铱（I）配合物2与氯代烷烃（例如CH_2Cl _2或CHCl_3）反应，得到二铱（II）产物[（Cl）（cod）Ir（μ-NH_2）_2Ir（cod）（R）]（R = CH_2Cl或CHCl_2）是两个中心氧化加成和伴随的金属-金属键形成的结果。然而，与ClCH_2CH _2Cl的反应在释放乙烯后提供了对称的加合物[{Ir（μ-NH_2）（Cl）（cod）} _ 2]。我们发现，铑配合物1在添加选定的膦（PPh_3，PMePh_2，PMe_2Ph）后逐步交换二烯烃，而不会裂开酰胺桥，从而可以检测混合的COD /膦双核配合物[（cod）Rh（μ- NH_2）_2Rh（PR_3）_2]，最后分离出相应的四膦[{Rh（μ-NH_2）（PR_3）_2} _2]。另一方面，铱配合物2通过分裂酰胺基桥而与PMe_2Ph反应并导致非常罕见的末端酰胺配合物[Ir（cod）（NH_2）（PMePh_2）_2]。发现该化合物对痕量水具有很高的反应性，可提供更稳定的末端羟基络合物[Ir（cod）（OH）（PMePh_2）_2]。杂环卡宾IPr（IPr = 1,3-双（2,6-二异丙基苯基）咪唑-2-亚基）还拆分了配合物1和2中的酰胺桥，从而在铱的情况下可以原位表征末端酰胺配合物[Ir（cod）（IPr）（NH _2）]。然而，当涉及铑时，已知的羟基络合物[Rh（cod）（IPr）（OH）]被分离为最终产物。另一方面，我们在不使用任何碱或在Cs _2CO_3存在的情况下，使用iPrOH在苯乙酮与iPrOH的加氢转移中测试了配合物1和2作为催化剂，发现铱配合物2比铑类似物1更具活性。紧密连接：已使用多种供体测试了[{M（μ-NH_2）（cod）} _ 2]类型的Rh和Ir的环辛二烯（鳕）配合物中NH_2桥的反应性和相对强度。通常，它们与金属紧密结合。使用二铱配合物和选定的配体，观察到末端[Ir（d〜8）-NH_2]物种的形成（参见方案）。

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