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首页> 外文期刊>Organometallics >Mechanistic study on the gas-phase generation of 'rollover'- Cyclometalated [M(bipy - H)]~+ (M = Ni, Pd, Pt)
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Mechanistic study on the gas-phase generation of 'rollover'- Cyclometalated [M(bipy - H)]~+ (M = Ni, Pd, Pt)

机译：环化金属[M（bipy-H）]〜+（M = Ni，Pd，Pt）气相生成“侧翻”的机理研究

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摘要

"Rollover"-cyclometalated [Pt(bipy - H)]~+ (bipy = 2,2′-bipyridine) can be easily generated in the gas phase via HX elimination brought about by collision-induced dissociation (CID) of the cationic complexes [Pt(X)(bipy)]~+ with X = CH_3, Cl; the latter as well as other [M(X)(bipy)]~+ complexes (M = Ni, Pd; X = CH_3, F, Cl, Br, I, OAc) are accessible by electrospray ionization mass spectrometry. For the nickel and palladium methyl complexes [M(CH _3)(bipy)]~+, upon CID, no cyclometalation occurs; rather, homolytic cleavage of the M-CH_3 bond takes place. The related chloro complexes [M(Cl)(bipy)]~+ (M = Ni, Pd) undergo competitive eliminations of HCl and Cl upon CID, and the branching ratios depend strongly on the collision energy. On the basis of DFT calculations, this metal- and ligand-controlled behavior is a consequence of the rather different energetic requirements for the direct loss of X versus elimination of HX (X = CH _3, Cl). Deuterium-labeling experiments reveal that formation of CH_4 and HCl is only for the platinum complexes due to a genuine "rollover" cyclometalation process, i.e., selective abstraction of a hydrogen atom from the C(3)-position of bipy. In the series of halo-substituted complexes [Ni(X)(bipy)]~+ (X = F, Cl, Br, I), the Ni-X bond strength decreases in the sequence F > Cl > Br > I. For X = F, one observes the elimination of HF, which benefits from the particular stability of this molecule; the hydrogen atom in HF is mostly (>90%) abstracted from position C(6) with <10% originating from C(3) of the bipy ligand; thus, for this system "rollover" cyclometalation occurs only to a small amount. [Ni(Cl)(bipy)]~+ undergoes competitive losses of HCl and Cl upon collision with Xe, and for X = Br and I only homolytic Ni-X bond cleavage takes place. In the elimination of HCl from [Ni(Cl)(bipy)]~+, >60% of the hydrogen atoms originate from C(3), and the remaining from C(4,5,6), as inferred from deuterium-labeling experiments. The acetate complexes [Ni(OAc)(bipy)]~+ and [Pd(OAc)(bipy)]~+ exhibit eliminations of neutral AcO~?, and at elevated collision energies, decarboxylation occurs. C-H bond activation resulting in the formation of HOAc is absent at the detection limit.
机译：通过阳离子络合物的碰撞诱导解离（CID）引起的HX消除，可以在气相中轻松生成“残留”-环金属化的[Pt（bipy-H）]〜+（bipy = 2,2'-联吡啶） [Pt（X）（bipy）]〜+其中X = CH_3，Cl;后者以及其他[M（X）（bipy）]〜+配合物（M = Ni，Pd; X = CH_3，F，Cl，Br，I，OAc）可通过电喷雾电离质谱法获得。对于镍和钯甲基配合物[M（CH _3）（bipy）]〜+，在CID下不会发生环金属化;而是发生M-CH_3键的均质裂解。相关的氯配合物[M（Cl）（bipy）]〜+（M = Ni，Pd）在CID下经历HCl和Cl的竞争性消除，并且支化比强烈取决于碰撞能量。根据DFT计算，这种金属和配体控制的行为是X的直接损失与HX的消除（X = CH _3，Cl）的完全不同的能量要求的结果。氘标记实验表明，CH_4和HCl的形成仅适用于铂配合物，这是由于真正的“翻转”环金属化过程，即从bipy的C（3）-位选择性提取氢原子。在一系列卤素取代的配合物[Ni（X）（bipy）]〜+（X = F，Cl，Br，I）中，Ni-X键强度按顺序F> Cl> Br> I降低。 X = F，人们观察到HF的消除，这得益于该分子的特殊稳定性; HF中的氢原子大部分（> 90％）从位置C（6）提取，其中<10％来自联吡啶配体的C（3）;因此，对于该系统，仅少量发生“翻滚”环化金属。 [Ni（Cl）（bipy）]〜+在与Xe碰撞时经历HCl和Cl的竞争性损失，并且对于X = Br和I，仅发生均相Ni-X键裂解。从[Ni（Cl）（bipy）]〜+中除去HCl时，如氘所示，> 60％的氢原子来自C（3），其余的来自C（4,5,6）。标记实验。乙酸盐络合物[Ni（OAc）（bipy）]〜+和[Pd（OAc）（bipy）]〜+表现出中性AcO〜α的消除，并且在提高的碰撞能量下发生脱羧。在检测极限处不存在导致HOAc形成的C-H键活化。

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