School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
J Am Chem Soc. 2011 Jun 15;133(23):8826-9. doi: 10.1021/ja201989c. Epub 2011 May 24.
The cationic zirconocene-phosphinoaryloxide complexes [Cp(2)ZrOC(6)H(4)P(t-Bu)(2)][B(C(6)F(5))(4)] (3) and [Cp*(2)ZrOC(6)H(4)P(t-Bu)(2)][B(C(6)F(5))(4)] (4) were synthesized by the reaction of Cp(2)ZrMe(2) or Cp*(2)ZrMe(2) with 2-(diphenylphosphino)phenol followed by protonation with [2,6-di-tert-butylpyridinium][B(C(6)F(5))(4)]. Compound 3 exhibits a Zr-P bond, whereas the bulkier Cp* derivative 4 was isolated as a chlorobenzene adduct without this Zr-P interaction. These compounds can be described as transition-metal-containing versions of linked frustrated Lewis pairs (FLPs), and treatment of 4 with H(2) under mild conditions cleaved H(2) in a fashion analogous to that for main-group FLPs. Their reactivity in amine borane dehydrogenation also mimics that of main-group FLPs, and they dehydrogenate a range of amine borane adducts. However, in contrast to main-group FLPs, 3 and 4 achieve this transformation in a catalytic rather than stoichiometric sense, with rates superior to those for previous high-valent catalysts.
阳离子茂锆-膦芳氧基配合物 [Cp(2)ZrOC(6)H(4)P(t-Bu)(2)][B(C(6)F(5))(4)] (3) 和 [Cp*(2)ZrOC(6)H(4)P(t-Bu)(2)][B(C(6)F(5))(4)] (4) 是通过 Cp(2)ZrMe(2) 或 Cp*(2)ZrMe(2) 与 2-(二苯基膦基)苯酚反应，然后用 [2,6-二叔丁基吡啶][B(C(6)F(5))(4)]质子化得到的。化合物 3 具有 Zr-P 键，而较大的茂基衍生物 4 则被分离为无 Zr-P 相互作用的氯苯加合物。这些化合物可以被描述为含有过渡金属的连接受阻路易斯对（FLP），并且在温和条件下用 H(2)处理 4 以类似于主族 FLP 的方式裂解 H(2)。它们在胺硼烷脱氢反应中的反应性也类似于主族 FLP，它们可以脱氢一系列胺硼烷加合物。然而，与主族 FLP 不同的是，3 和 4 以催化而不是化学计量的方式实现了这种转化，其速率优于以前的高价催化剂。
