Hydrogen atoms location in Os3(mu-H)(CO)9(mu3,eta2-C2H) from accurate X-ray data at 100 K

The structure of the complex Os3(l-H)(CO)9 (l3, g2-C2H) has been determined using X-ray data collected at low temperature (100 K); all hydrogen atoms have been located. The asymmetric unit is formed by two molecules joined through hydrogen bonds involving the hydrogen atoms of C2H moiety and the oxygen atoms of carbonyl groups. The complex crystallizes in the monoclinic space group P21/c with a = 12.94040(2), b = 15.4705(2), c = 16.0164(2) A ° , b = 106.0860(10), and V = 3,080.85(7) A ° 3, Z = 8. A molecule is formed by a triangular Os3 cluster, with metal atoms bearing terminal CO groups. The acetylenic residual is formally p-bonded to two Os atoms in a perpendicular mode and r-linked to the third Os atom. A bridging hydride atom completes the coordination.