Haufe Lisa C, Endres Lukas, Arrowsmith Merle, Bertermann Rüdiger, Dietz Maximilian, Fantuzzi Felipe, Finze Maik, Braunschweig Holger
Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
J Am Chem Soc. 2023 Nov 8;145(44):23986-23993. doi: 10.1021/jacs.3c06259. Epub 2023 Oct 24.
The 1,3-addition of 1,2-diaryl-1,2-dibromodiboranes (BBrAr) to -[W(N)(dppe)] (dppe = κ-(PhPCH)), which is accompanied by a Br-Ar substituent exchange between the two boron atoms, is followed by a spontaneous rearrangement of the resulting tungsten diboranyldiazenido complex to a 2-aza-1,3-diboraallenylimido complex displaying a linear, cumulenic B=N=B moiety. This rearrangement involves the splitting of both the B-B and N=N bonds of the NB ligand, formal insertion of a BAr boranediyl moiety into the N=N bond, and coordination of the remaining BArBr boryl moiety to the terminal nitrogen atom. Density functional theory calculations show that the reaction proceeds via a cyclic NB intermediate, followed by dissociation into a tungsten nitrido complex and a linear boryliminoborane, which recombine by adduct formation between the nitrido ligand and the electron-deficient iminoborane boron atom. The linear B=N=B moiety also undergoes facile 1,2-addition of Brønsted acids (HY = HOPh, HSPh, and HNPh) with concomitant Y-Br substituent exchange at the terminal boron atom, yielding cationic (borylamino)borylimido tungsten complexes.
1,2-二芳基-1,2-二溴二硼烷（BBrAr）与-[W(N)(dppe)]（dppe = κ-(PhPCH)）发生1,3-加成反应，伴随两个硼原子之间的Br-Ar取代基交换，随后生成的钨二硼烷基二氮烯基配合物自发重排为具有线性、累积烯型B=N=B部分的2-氮杂-1,3-二硼丙二烯基亚氨基配合物。这种重排涉及NB配体的B-B键和N=N键的断裂，BAr硼二价部分正式插入N=N键，以及剩余的BArBr硼基部分与末端氮原子配位。密度泛函理论计算表明，反应通过环状NB中间体进行，随后分解为钨氮化物配合物和线性硼基亚氨基硼烷，它们通过氮化物配体与缺电子亚氨基硼烷硼原子之间形成加合物而重新结合。线性B=N=B部分也容易与布朗斯特酸（HY = HOPh、HSPh和HNPh）发生1,2-加成反应，同时在末端硼原子处发生Y-Br取代基交换，生成阳离子（硼氨基）硼基亚氨基钨配合物。
