Tl(I) complexes of cymantrene-based tris(1-pyrazolyl)borates: polymers and macrocycles

摘要

Cymantrene-based tris(1-pyrazolyl)borates have been synthesized from the reaction of CymBBr_2 and Cym'BBr_2 with pyrazole (Hpz) in the presence of triethylamine [Cym: cymantrenyl; Cym': (methyl)cymantrenyl]. The Tl(I) salts CymB(pz)_3Tl, 2a, and Cym'B(pz)_3Tl, 2b, have been structurally characterized by X-ray crystallography. Similar to the corresponding complex FcB(pz)_3Tl (Fc: Ferrocenyl), CymB(pz)_3Tl features a polymeric structure with bridging [B(pz)_3] fragments in the solid state. Cym'B(pz)_3Tl shows a related oligomeric structure. This time a macrocyclic tetramer rather than a linear chain is observed. To provide a ligand of high solubility in non-polar solvents, compound Cym'B(pz~(4-R))_3Tl, [R = CH_2(C_6H_(11))]2d, has been synthesized, which shows a reduced symmetry at the organometallic moiety, together with (cyclohexyl)methyl substituents in the 4-positions of all pyrazolyl rings.