Diverse ligand substitution behavior in the reaction of H_4O_s_4(CO)_(12) with 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and Me_3NO: Spectroscopic characterization of the diphosphine chelating and bridging isomers H_4O_s_4(CO)_(10)(bpcd) and the X-ray diffraction structures of the tetraosmium clusters H_4O_s_4(CO)_(11)(NMe_3) and 1,2-H_4O_s_4(CO)_(10)(NMe_3)(η~1-bpcd)

摘要

The reaction between the tetraosmium cluster H $_{4}hbox{Os}_{4}$ (CO) $_{12}$ and the unsaturated diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) has been examined in CH $_{2}hbox{Cl}_{2}$ solvent and in the presence of the oxidative-decarbonylation reagent Me $_{3}$ NO. Rapid ligand substitution is observed and the four products H $_{4}hbox{Os}_{4}$ (CO) $_{11}$ (NMe $_{3}$ ), 1,1-H $_{4}hbox{Os}_{4}$ (CO) $_{10}$ (bpcd), 1,2-H $_{4}hbox{Os}_{4}$ (CO) $_{10}$ (bpcd), and 1,2-H $_{4}hbox{Os}_{4}$ (CO) $_{10}$ (NMe $_{3}$ ) ( $eta^{1}$ -bpcd) have been isolated and characterized in solution by IR and NMR spectroscopies. The molecular structures of H $_{4}hbox{Os}_{4}$ (CO) $_{11}$ (NMe $_{3}$ ) and 1,2-H $_{4}hbox{Os}_{4}$ (CO) $_{10}$ (NMe $_{3}$ )( $eta^{1}$ -bpcd) have been crystallographically determined. H $_{4}hbox{Os}_{4}$ (CO) $_{11}$ (NMe $_{3}$ ) crystallizes in the orthorhombic space group $hbox{it Pca}2_{1}, a=19.907(3)$ Å, $b = 8.137(1)$ Å, $c = 13.796(2)$ Å, $V=2234.6(6)$ Å3, Z=4, and $d_{rm calc} = 3.353$ mg/m3; $R=0.0418, R_{rm w} = 0.1071$ for 4997 reflections with $I>2 sigma(I)$ . 1,2-H $_{4}hbox{Os}_{4}$ (CO) $_{10}$ (NMe $_{3}$ )( $eta^{1}$ -bpcd) crystallizes in the monoclinic space group $P2_{1}/c, a = 21.0173(3)$ Å, $b = 10.755(2)$ Å, $c = 23.135(4)$ Å, $V = 4950.5(1)$ Å3, Z=4, and $d_{rm calc} = 2.099$ mg/m3; $R = 0.0591, R_{rm w} = 0.1046$ for 10,766 reflections with $I>2sigma(I)$ . The monodentate coordination of the bpcd ligand in 1,2-H $_{4}hbox{Os}_{4}$ (CO) $_{10}$ (NMe $_{3}$ )( $eta^{1}$ -bpcd) and the disposition of the NMe $_{3}$ and bpcd ligands across one of the Os–Os bonds are crystallographically verified.