Rh(I) Complex with a Tridentate Pyridine–Amino–Olefin Actor Ligand–Metal–Ligand Cooperative Activation of CO2 and Phenylisocyanate under C–C and Rh–E (E = O, N) Bond Formation,Organometallics

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Rh(I) Complex with a Tridentate Pyridine–Amino–Olefin Actor Ligand–Metal–Ligand Cooperative Activation of CO2 and Phenylisocyanate under C–C and Rh–E (E = O, N) Bond Formation
Organometallics ( IF 2.5 ) Pub Date : 2019-04-09 , DOI: 10.1021/acs.organomet.9b00094
Isabell Heuermann ₁ , Benjamin Heitmann ₁ , Rasmus Stichauer ₁ , Daniel Duvinage ₁ , Matthias Vogt ₁

Affiliation

We synthesized and characterized the novel olefinic multidentate actor ligand dbap-py. The ligand consists of a 2-methyl pyridine unit and an azepine component fused by an N-alkylation. The coordination chemistry to Rh(I) centers was explored and dbap-py revealed interesting tridentate chelation (pyridine–amine–olefin), which can suit square planar as well as distorted trigonal bipyramidal coordination spheres in Rh(I) complexes. Most notably, dbap-py in [Rh(dbap-py)(PPh₃)Cl] (3) entails an acidic benzylic methylene moiety, which is readily deprotonated allowing for the formation of the neutral square planar complex [Rh(dbap-py*)(PPh₃)] (4, the asterisk indicates the deprotonated ligand). As a result, the deprotonation disrupts the aromatic π-system of the pyridine unit in 4 and a C-nucleophilic methine moiety is formed. Complex 4 reacts in tetrahydrofuran solution at ambient temperature rapidly with C═O bonds present in CO₂ or the N═C bond of phenyl isocyanate (Ph-NCO) to give the penta-coordinated rhodium κ¹-O carboxylate [Rh(dbap-COO)(PPh₃)] (5) and the rhodium κ¹-N amidate [Rh(dbap-NCO)(PPh₃)] (6), respectively. Both reactions are characterized by a C–C and Rh–E (E = O (5); N (6)) bond formation under concomitant redistribution of the ligand’s π-system of the pyridine unit (“rearomatization”). To the best of our knowledge, compound 6 gives precedence to Rh(I) complexes with a κ¹-N amidate ligand. Remarkably, metal–ligand cooperation is key to the uptake of Ph-NCO and allows for a convenient access to an amidate ligand motif.

中文翻译：

具有三齿吡啶-氨基-烯烃演员配体-金属-配体的Rh（I）配合物在CC和Rh-E（E = O，N）键形成下协同活化CO ₂和苯基异氰酸酯

我们合成并表征了新型烯烃多齿演员配体dbap-py。该配体由2-甲基吡啶单元和通过N-烷基化稠合的氮杂组分组成。探索到Rh（I）中心的配位化学，并且dbap-py显示了有趣的三齿螯合（吡啶-胺-烯烃），它可以适合Rh（I）络合物中的方形平面以及扭曲的三角双锥体配位球。最值得注意的是，DBAP吡在的[Rh（DBAP-PY）（PPH ₃）CL]（3）仅涉及酸性苄亚甲基部分，其被容易地去质子化允许在中性平面方形络合物的[Rh（DBAP-PY的形成*）（PPh ₃）]（4，星号表示去质子化的配体）。结果，去质子破坏了吡啶单元中的4的芳族π系统，并形成了C-亲核次甲基部分。复杂4种在环境温度下的四氢呋喃溶液快速地发生反应与C = O键存在于CO ₂或苯基异氰酸酯的N = C键（PH-NCO），得到五配位的铑κ ¹ - ö羧酸的[Rh（dbap- COO）（PPH ₃）]（5）和铑κ ¹ - ñ酰胺化物的[Rh（DBAP-NCO）（PPH ₃）]（6分别地）。这两个反应的特征都是C–C和Rh–E（E = O（5）; 在吡啶单元的配体的π系统伴随重新分布的情况下形成N（6））键（“芳香化”）。据我们所知，化合物6给出的优先的Rh（I）与κ络合物¹ - ñ酰胺化物配体。值得注意的是，金属-配体的合作是摄取Ph-NCO的关键，并可以方便地获得酰胺化物的配体基序。

更新日期：2019-04-09

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