Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
Nat Commun. 2018 Sep 24;9(1):3866. doi: 10.1038/s41467-018-06324-9.
Nickel-catalyzed catalyst transfer polycondensation (CTP) of thiophenes is an efficient strategy for the controlled synthesis of polythiophenes. However, a detailed view of its reaction mechanism has remained elusive with unresolved questions regarding the geometry and bonding of critical Ni(0) thiophene intermediates. Herein, we provide experimental and computational evidence of structurally characterized square planar η-Ni(0)-thiophene species and their relevance to the mechanism of CTP. These results confirm the viability of C,C-η bound intermediates in CTP of thiophenes, providing an electronic rationale for the stability of such species, and thus that such processes can proceed as living polymerizations. We further show that C,S-κ species may also be relevant in nickel-catalyzed CTP of thiophenes, providing new avenues for exploitation and optimization.
镍催化的噻吩转移聚合（CTP）是一种有效的可控合成聚噻吩的方法。然而，其反应机制的详细情况仍然难以捉摸，关键的 Ni(0)噻吩中间体的几何形状和键合问题仍未解决。在此，我们提供了实验和计算证据，证明了结构特征明确的平面正方形 η-Ni(0)-噻吩物种的存在，以及它们与 CTP 机制的相关性。这些结果证实了 C,C-η 键合中间体在噻吩 CTP 中的可行性，为这种物种的稳定性提供了电子原理，因此此类过程可以作为活性聚合进行。我们还进一步表明，C,S-κ 物种在镍催化的噻吩 CTP 中也可能相关，为其开发和优化提供了新途径。
