Terminal iron dinitrogen and iron imide complexes supported by a tris(phosphino)borane ligand.
Terminal iron dinitrogen and iron imide complexes supported by a tris(phosphino)borane ligand.
复制标题
DOI：
10.1002/anie.201006918
复制
发表时间：
2011-02-25
影响因子：
16.6
通讯作者：
Peters, Jonas C.
中科院分区：
文献类型：
--
作者：
Moret, Marc-Etienne;Peters, Jonas C.
我们目前对生物固氮[1]（即通过添加质子和电子将N2还原为两个等量的氨）机制的了解有限，这促使我们持续努力制备氮酶mofe辅助因子的功能模型。一种可能的N2还原机制是所谓的远端或chatt型循环[2]，其中三个氢原子等价物依次添加到金属结合的二氮分子（M - N≡N）的远端N原子上，导致一个等价物NH3的消除，产生中间氮络合物（M≡N）。后者又通过与另外三个质子和电子的反应转化为氨。事实上，这样的循环被认为对单核钼基催化剂是可行的越来越多的证据表明，在MoFe辅助因子中，铁的底物配位[1b]保证了在相关背景下对铁基模型的持续研究。铁中心的chatt型循环需要单个配体支架来稳定含π酸性二氮分子的低价配合物和含π碱性氮化物配体的高价配合物。我们的研究小组在两种不同的配体几何结构中研究了这种化学反应，这些配体几何结构模拟了fe辅因子中铁的局部三角对称配位环境。伪四面体结构已被成功地用于稳定末端亚胺[5,6]和氮化物[7,8]配体，因为e亲系的π-反键d轨道通常是空的，但由于难以实现足够的空间保护，这种几何结构中的大多数N2配合物都是双核的桥接物，而不是末端的。[9,10]另一方面，四齿三（膦）硅基配体的三角-双锥体结构已被证明可以稳定末端N2配合物
Our currently limited understanding of the mechanism of biological dinitrogen fixation [1]–ie the reduction of N2 to two equivalents of ammonia by addition of protons and electrons–motivates a sustained effort towards the preparation of functional models of the nitrogenase MoFe-cofactor. One plausible mechanism for N2 reduction is a so-called distal or Chatt-type cycle [2], in which three hydrogen-atom equivalents are successively added to the distal N-atom of a metal-bound dinitrogen molecule (M–N≡ N), resulting in the elimination of one equivalent of NH3 to yield an intermediate nitrido complex (M≡ N). The latter is in turn converted to ammonia by reaction with three additional protons and electrons. Indeed, such a cycle has been suggested as operative for a mononuclear, molybdenum-based catalyst.[3] The increasing evidence for substrate coordination at iron in the MoFe cofactor [1b] warrants the continued investigation of iron-based models in a related context.[4]A Chatt-type cycle at an iron center would require a single ligand scaffold to stabilize lowvalent complexes with a π-acidic dinitrogen molecule as well as high valent complexes with a π-basic nitride ligand. Our group has investigated this chemistry in two different ligandimposed geometries that model the local trigonal symmetry of the coordination environment of iron in the MoFe cofactor. The pseudotetrahedral geometry has been successfully used to stabilize terminal imide [5, 6] and nitride [7, 8] ligands because the π-antibonding d-orbitals of e parentage are usually empty, but most of the N2 complexes in this geometry are dinuclear, bridged species rather than terminal ones due to the difficulty of implementing sufficient steric protection.[9, 10] On the other hand, the trigonal-bipyramidal geometry enforced by tetradentate tris (phosphino) silyl ligands has been shown to stabilize terminal N2 complexes
登录
查看更多内容
影响因子：
4.6
作者：
Bontemps, Sebastien;Bouhadir, Ghenwa;Bourissou, Didier
通讯作者：
Bourissou, Didier
影响因子：
4
作者：
Crossley, Ian R.;Hill, Anthony F.
通讯作者：
Hill, Anthony F.
影响因子：
2.8
作者：
Crossley, Ian R.;Hill, Anthony F.;Willis, Anthony C.
通讯作者：
Willis, Anthony C.
影响因子：
15
作者：
Brown, SD;Peters, JC
通讯作者：
Peters, JC
影响因子：
2.8
作者：
Crossley, IR;Hill, AF
通讯作者：
Hill, AF