MODELS FOR LINEAR ACETYLIDE POLYMERS - SYNTHESIS AND SINGLE-CRYSTAL X-RAY STRUCTURES OF THE RUTHENIUM(II) ACETYLIDE AND DIACETYLIDES RU(CO)2(PET3)2[(C-EQUIVALENT-TO-C)NR]2 (N = 1, R = ME3SI N = 2, R = ME3SI, H)

As model compounds for long-chain, linear, acetylide-based polymers, the bis(acetylides) and bis (diacetylides) of ruthenium(II) trans-Ru(CO)2(PEt3)2[(C=C)nR], (2, n = 1, R = Me3Si; 3, n = 2, R = Me3Si; 4BAR, n = 2, R = H) have been synthesized and fully characterized by IR and Raman spectroscopy, H-1, C-13{H-1}, and P-31{H-1} NMR studies, and single-crystal X-ray diffraction. Complex 2 crystallizes in the monoclinic space group P2(1)/c with Z = 2 in a unit cell of dimensions a = 11.733 (3) angstrom, b = 10.944 (3) angstrom, c = 13.414 (4) angstrom, and beta = 111.65 (2)-degrees. The structure was solved and refined using 4091 observed reflections measured on a SiemenB R3m/v diffractometer to a final R value of 2.66%. Crystals of 3 are monoclinic, space group P2(1)/c, with a = 13.980 (4) angstrom, b = 10.324 (2) angstrom, c = 13.146 (3) angstrom, beta = 115.18(2)-degrees, and Z = 2. On the basis of 4141 observed reflections, the structure was refined to R = 2.79. Crystals of 4 are monoclinic, space group P2(1)/c, with a = 7.642 (2) angstrom, b = 9.167 (2) angstrom, c = 16.493 (3) angstrom, beta = 93.05 (2)-degrees, and Z = 2. For 2905 observed reflections R was 2.56%. All three structure determinations were of high quality. Comparison of bond lengths between these complexes and related acetylides suggests that the trimethylsilyl-substituted bis(acetylides) or bis(diacetylides) have greater multiple-bond character in metal to acetylene sigma bonds than other acetylide derivatives.