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Keywords:

  • boratabenzene;
  • boron;
  • click chemistry;
  • iron;
  • metallopolymers;
  • polymerization

Abstract

Boratabenzene-derived metallocene analogues are introduced as versatile new building blocks for metallopolymers. Bis(borinato)iron(II) complexes of the type Fe(C5H5B[BOND]R)2 (R: C[TRIPLE BOND]CH, C[TRIPLE BOND]CSiMe3, 4-(1-benzyl-1,2,3-triazolyl) were synthesized and spectroscopically, structurally, and electrochemically characterized. Polymerization via Sonogashira–Hagihara coupling of the alkynyl-substituted derivative Fe(C5H5B[BOND]C[TRIPLE BOND]CH)2 with 2,5-bis(dodecyloxy)-1,4-diiodobenzene yields a film-forming polymer in 50–69 % yield. Polymer batches were obtained with number-average molecular weights (Mn) of 11.7 and 20.5 kDa and polydispersity indices (PDI) of 1.55 and 2.65, respectively, as determined by gel permeation chromatography relative to polystyrene standards. Click-type polymerization of Fe(C5H5B[BOND]C[TRIPLE BOND]CH)2 through azide–alkyne cycloaddition with 1,4-bis(4-azidobutoxy)benzene gives the corresponding metallopolymer with an Mn of 5.7 kDa and a PDI of 2.29 in 87 % yield.