engleski

Raman spectroscopy of three average-valence dicopper cryptates: Evidence for copper-copper bonding

Comparison of the X-ray structures of two pairs of dicopper(I) and dicopper(1.5) cryptates provides evidence (over 0.5 Å contraction of the internuclear distance in one pair) for copper−copper bond formation. Although resonance Raman spectroscopy fails to identify a pure copper−copper stretching mode, because of extensive mixing of several low-frequency stretching and bending modes, isotopic substitution experiments indicate significant Cu−Cu character in a band around 250 cm-1. A normal coordinate analysis broadly supports the spectroscopic findings. X-ray crystal structures are presented for the dicopper(1.5) complex Cu2imBT(ClO4)3, C18H30Cl3Cu2N8O12, a = 9.140(4) Å, c = 30.35(3) Å, rhombohedral, R32, Z = 3, and the dicopper(I) Cu2imbistrpn(ClO4)2, C24H42Cl2Cu2N8O8, a = 9.279(2) Å, c = 32.846(9) Å, rhombohedral, R32, Z = 3.

copper cryptates ; copper-copper bond

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