X-ray diffraction study of the products of reaction between copper(I) chloride and propargyl alcohol in the presence of pyridinium chloride

The (PyH)[CuCl2] (I), (PyH)(2)[Cu8Cl8(C=CH2OH)(2)]. H2O (II), and (PyH)(4)[ Cu9Cl12(C=CH)] (III) complexes were obtained as single crystals in a PyHCl- CuCl-H2O-HC=CCH2OH system (PyH+ is the pyridinium cation C5H5NH+) acid X-ra y structurally characterized analysis (a DARCh automated diffractometer, la mbda MoKalpha, theta/2 theta scan mode; 1551, 4024, and 393 independent ref lections with F greater than or equal to 4 sigma(F); R = 0.044, 0.032, and 0.068 for I, II, and III, respectively). Crystals I and III are monoclinic; space groups P2(1)/m and B2/m, Z = 6 and 2, a = 9.100(3) and 19.798(4), b = 10.057(3) and 7.980(3), c = 13.226(5) and 12,979(6) Angstrom, gamma = 112 .59(2)degrees and 105.77(2)degrees for I and III, respectively. Crystals II are triclinic, space group P (1) over bar, Z = 2, a = 13.818(3), b = 11.87 6(3), c = 8.901(3) Angstrom, alpha = 93.50(2)degrees, beta = 79.22(2)degree s, gamma = 101.82(2)degrees. Unlike I, acetylide pi-complex II contains two crystallographically independent C-=CCH2OH particles whose C=C groups diff er in the ability to coordinate with Cu(I). The C(4)=C(5) bond of one of th e hydroxypropynide anions is simultaneously coordinated to four (pi, pi and sigma, sigma bonds) metal atoms, while the C(1)=C(2) bond is coordinated t o five (pi, pi and sigma, sigma, sigma bonds) metal atoms. This results in the [Cu-8(C=CCH2OH)(2)] cluster, in which the shortest Cu ... Cu distance i s equal to 2.545(3) Angstrom. The C-=CH particle appears in complex III as a result of the catalytic transformation of propargyl alcohol and is linked to two Cu(I) atoms only via sigma-bonds.