Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
Inorg Chem. 2013 Jul 1;52(13):7593-607. doi: 10.1021/ic400684s. Epub 2013 Jun 13.
A straightforward synthesis of a new hybrid scorpionate ligand (allyl)2B(CH2PPh2)(Pz) (A2BPN) is reported. Coordination to rhodium resulted in square-planar complexes [Rh(κ(2)-A2BPN)(L)(L')] [L = L' = (1)/2cod (1,5-cyclooctadiene), CN(t)Bu, CO (6); L = CO, L' = NH3, pyridine, PPh3, PMe3] for which spectroscopic data and the molecular structure of [Rh(κ(2)-A2BPN)(CO)PPh3] (11) indicate the ligand to be κN,κP-bound to rhodium with two dangling free allyl groups. Studies in solution point out that the six-membered Rh-N-N-B-C- P metallacycle undergoes a fast inversion in all of them. The bis(carbonyl) complex 6 easily loses a CO group to give [{Rh(A2BPN)(CO)}2], a dinuclear compound in which two mononuclear subunits are brought together by two bridging allyl groups. Coordination to iridium is dominated by a tripodal κN,κP,η(2)-C═C binding mode in the TBPY-5 complexes [Ir(κ(3)-A2BPN)(L)(L')] [L = L' = (1)/2cod (3), CN(t)Bu (5), CO (7); L = CO, L' = PPh3 (13), PMe3 (14), H2C═CH2, (17), MeO2CC≡CCO2Me (dmad, 18)], as confirmed by the single-crystal structure determination of complexes 3 and 18. A fast exchange between the two allyl arms is observed for complexes having L = L' (3, 5, and 7), while those having CO and L ligands (14, 17, and 18) were found to be nonfluxional species. An exception is complex 13, which establishes an equilibrium with the SP-4 configuration. Protonation reactions on complexes 13 and 14 with HCl yielded the hydride complex [Ir(κ(2)-A2BPN)(CO)(Cl)(H)PPh3] (15) and the C-alkyl compound [ Ir{κ(3)-(allyl)B(CH2 CHCH3)(CH2PPh2)(Pz)}(Cl)(CO)PMe3] (16), respectively. The bis(isocyanide) complex 5 reacts with dmad to form [Ir(κ(2)-A2BPN)(CN(t)Bu)2(dmad)]. On the whole, the electronic density provided to the metal by the A2BPN ligand is very sensitive to the coordination mode. The basicity of the new ligand is similar to that of the Tp(Me2) ligand in the κN,κP mode but comparable to Tp if coordinated in the κN,κP,η(2)-C═C mode.
一种新的混合型硫代膦酸酯配体[(烯丙基)2B(CH2PPh2)(Pz)]-([A2BPN]-)的直接合成方法被报道。与铑配位得到了平面正方形配合物[Rh(κ(2)-A2BPN)(L)(L')] [L = L' = (1)/2cod(1,5-环辛二烯), CN(t)Bu, CO(6); L = CO, L' = NH3, 吡啶, PPh3, PMe3]，其中[Rh(κ(2)-A2BPN)(CO)PPh3] (11)的光谱数据和分子结构表明该配体与铑配位为κN,κP，具有两个悬空的游离烯丙基基团。在溶液中的研究表明，六元Rh-N-N-B-C-P金属环在所有这些配合物中都能快速翻转。双(羰基)配合物 6 容易失去一个 CO 基团得到[{Rh(A2BPN)(CO)}2]，这是一种双核化合物，其中两个单核亚基通过两个桥接的烯丙基基团结合在一起。与铱配位主要以三齿κN,κP,η(2)-C═C 结合模式存在于 TBPY-5 配合物[Ir(κ(3)-A2BPN)(L)(L')] [L = L' = (1)/2cod(3), CN(t)Bu(5), CO(7); L = CO, L' = PPh3(13), PMe3(14), H2C═CH2(17), MeO2CC≡CCO2Me(dmad, 18)]中，这一点通过配合物 3 和 18 的单晶结构确定得到了证实。对于具有 L = L' (3, 5 和 7)的配合物，观察到两个烯丙基臂之间的快速交换，而对于具有 CO 和 L 配体的配合物(14, 17 和 18)则发现是非通量物种。一个例外是配合物 13，它与 SP-4 构型建立了平衡。用 HCl 对配合物 13 和 14 进行质子化反应，得到了氢化物配合物[Ir(κ(2)-A2BPN)(CO)(Cl)(H)PPh3] (15)和 C-烷基化合物[Ir{κ(3)-(烯丙基)B(CH2 CHCH3)(CH2PPh2)(Pz)}(Cl)(CO)PMe3] (16)。双(异氰化物)配合物 5 与 dmad 反应生成[Ir(κ(2)-A2BPN)(CN(t)Bu)2(dmad)]。总的来说，[A2BPN]-配体提供给金属的电子密度对配位模式非常敏感。新配体的碱性与 κN,κP 模式下的 Tp(Me2)配体相似，但与 Tp 相比，如果以 κN,κP,η(2)-C═C 模式配位，则具有可比性。
