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Cu(I) acetylide clusters decorated with pyridylphosphine ligands: structural diversity, cuprophilic interactions and phosphorescence properties
The reaction of copper(I) phenylacetylide [PhC ≡ CCu]n with the 2-pyridylphosphines (tBu2PyP and Ph2PyP) offers a straightforward route to structurally diverse clusters. With tBu2PyP, a trinuclear cluster [Cu3(C ≡ CPh)3(tBu2PyP)3] featuring a Cu3 triangular was isolated. Surprisingly, the reaction of [PhC ≡ CCu]n with Ph2PyP yields two isomeric clusters [Cu4(C ≡ CPh)4(Ph2PyP)4] with tetrahedral or zigzag-arranged Cu4 cores. Upon prolonged storage in acetonitrile, the tetrahedral Cu4 cluster converts to the dinuclear cluster [Cu2(C ≡ CPh)2(Ph2PyP)3]. All these clusters exhibit short Cu···Cu contacts (2.395–2.677 Å, cf. ΣrvdW(Cu···Cu) = 2.80 Å), but QTAIM analysis reveals cuprophilic interactions only in the Cu2 cluster (dCu–Cu = 2.395 Å). Temperature-dependent phosphorescence of the Cu3 cluster was also studied and rationalized theoretically.