Esteruelas Miguel A, Martínez Antonio, Oliván Montserrat, Oñate Enrique
Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza-CSIC, 50009, Zaragoza, Spain.
Chemistry. 2020 Oct 1;26(55):12632-12644. doi: 10.1002/chem.202001838. Epub 2020 Sep 7.
The saturated trihydride IrH {κ -P,O,P-[xant(PiPr ) ]} (1; xant(PiPr ) =9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) activates the B-H bond of two molecules of pinacolborane (HBpin) to give H , the hydride-boryl derivatives IrH (Bpin){κ -P,O,P-[xant(PiPr ) ]} (2) and IrH(Bpin) {κ -P,O,P-[xant(PiPr ) ]} (3) in a sequential manner. Complex 3 activates a C-H bond of two molecules of benzene to form PhBpin and regenerates 2 and 1, also in a sequential manner. Thus, complexes 1, 2, and 3 define two cycles for the catalytic direct C-H borylation of arenes with HBpin, which have dihydride 2 as a common intermediate. C-H bond activation of the arenes is the rate-determining step of both cycles, as the C-H oxidative addition to 3 is faster than to 2. The results from a kinetic study of the reactions of 1 and 2 with HBpin support a cooperative function of the hydride ligands in the B-H bond activation. The addition of the boron atom of the borane to a hydride facilitates the coordination of the B-H bond through the formation of κ - and κ -dihydrideborate intermediates.
饱和三氢化物IrH{κ -P,O,P-[呫吨(PiPr ) ]} (1; 呫吨(PiPr ) =9,9-二甲基-4,5-双(二异丙基膦基)呫吨)依次活化两分子频哪醇硼烷(HBpin)的B-H键生成H ，得到氢化物-硼基衍生物IrH (Bpin){κ -P,O,P-[呫吨(PiPr ) ]} (2)和IrH(Bpin) {κ -P,O,P-[呫吨(PiPr ) ]} (3)。配合物3也依次活化两分子苯的C-H键形成PhBpin并再生2和1。因此，配合物1、2和3定义了两个用HBpin对芳烃进行催化直接C-H硼化的循环，它们以二氢化物2作为共同中间体。芳烃的C-H键活化是两个循环的速率决定步骤，因为C-H对3的氧化加成比对2的快。对1和2与HBpin反应的动力学研究结果支持了氢化物配体在B-H键活化中的协同作用。硼烷的硼原子加到氢化物上通过形成κ -和κ -二氢硼酸盐中间体促进了B-H键的配位。
