Copper(I) alkynyl clusters, [Cu(x+y)(hfac)(x)(C[triple chemical bond]CR)(y)], with Cu(10)-Cu(12) cores

The facile syntheses and the structures of five new Cu(I) alkynyl clusters, Cu(12)(hfac)(8)(Ctriple chemical bond]CnPr)(4)(thf)(6)]xTHF (1), Cu(12)(hfac)(8)(Ctriple chemical bond]CtBu)(4)] (2), Cu(12)(hfac)(8)(Ctriple chemical bond]CSiMe(3))(4)] (3), Cu(10)(hfac)(6)(Ctriple chemical bond]CtBu)(4)(diethyl ether)]/Cu(10)(hfac)(6)(Ctriple chemical bond]CtBu)(3)(Ctriple chemical bond]CnPr)(diethyl ether)] (4) and Cu(10)(hfac)(6)(Ctriple chemical bond]CtBu)(4)(diethyl ether)] (5) are reported, in which hfacH=1,1,1,5,5,5-hexafluoropentan-2,4-dione. The first independent molecule found in the crystals of 4 (4 a) proved to be chemically identical to 5. The Cu(10) and Cu(12) cores in these clusters are based on a central "square" Cu(4)C(4) unit. Whilst the connectivities of the Cu(10) or Cu(12) units remain identical the geometries vary considerably and depend on the bulk of the alkynyl group, weak coordination of ether molecules to copper atoms in the core and CuO intramolecular contacts formed between Cu-hfac units on the periphery of the cluster. Similar intermolecular contacts and interlocking of Cu-hfac units are formed in the simple model complex Cu(2)(hfac)(2)(HCtriple chemical bond]CtBu)] (6). When linear alkynes, C(n)H(2n+1)Ctriple chemical bond]CH, are used in the synthesis and non-coordinating solvents are used in the workup, further association of the Cu(4)C(4) cores occurs and clusters with more than eighteen copper atoms are isolated.