The Structure of the “Third‐Generation” Tris(pyrazolyl)borate Caesium Salt p‐BrC6H4TpCs

Slow crystallisation at lowered temperature yielded crystals of the “third‐generation” tris(pyrazolyl)borate transfer agent p‐BrC₆H₄TpCs (Tp′Cs) 1 (triclinic; P$bar{1}$ ; a = 8.540(4), b = 15.045(6), c = 15.879(7) Å; α = 65.853(8), β = 88.457(8), γ = 75.056(8)°; V = 1791.4(13) Å³; Z = 4). The central caesium ion in 1 interacts with three individual p‐BrC₆H₄Tp ligands in two different chelating fashions.In particular, κ¹‐N‐coordination and η⁵‐π‐coordination of pyrazole moieties as well as η⁶‐π‐coordination of the p‐BrC₆H₄ substituent are observed. Further, comparable coordination of neighbouring caesium ions leads to the formation of polymeric structures connected by two bridging modes.