X-ray diffraction structures of two isomeric decacarbonyltriosmium compounds of quinoxaline, [(μ-H)Os₃(CO)₁₀(μ-1, 8-η²-C₈H₅N₂)] and [(μ-H)Os₃(CO)₁₀(μ-1, 2-η²- C₈H₅N₂)]

Abstract

Treatment of [Os₃(Co)₁₀(MeCN)₂] with quinoxaline at room temperature results in the isolation of two isomeric clusters &nbsp;[(μ-H)Os₃(CO)₁₀(μ-1, 8-η²-C₈H₅N₂)]<b>5</b> and [(μ-H)Os₃(Co)₁₀(μ-1, 2-η²- C₈H₅N₂)]<b>6</b> in 50 and 10% yields respectively. Compounds <b>5</b> and <b>6</b> have been characterized by spectroscopic data and single crystal X-ray diffraction studies. Compound <b>5</b> crystallizes in the triclinic space group <i>P-</i>1<i> </i>with <i>a= </i>7.895(2) Å, <i>b </i>= 9.187(2)Å, <i>c </i>= 16.741(3)Å, α= 75.494(12), β =88.60(2), γ = 66.57(2)^o, Z = 2, <i>V </i>= 1074.8(4) ųand <i>d</i>_calc= 3.031 mg/m³; <i>R</i>₁= 0.0364, w<i>R</i>₂ = 0.0870 for 2958 reflections with <i>I&gt; </i>2ϭ (<i>I</i>). Compound 6 crystallizes together with an entirely independent molecule of the previously reported hydridehydroxy compound [(μ-H)Os₃(CO)₁₀(μ-OH)] <b>7</b> in the monoclinic space group <i>P</i>2₁/n with <i>a= </i>9.255(2) Å, <i>b </i>= 16.864(3) Å, <i>c </i>= 26.243(7) Å, α = 90, β = 91.36(2), γ = 90°, Z = 4, <i>V </i>= 4094.8(16) ų and <i>d</i>_calc = 3.135 mg/m³ ; <i>R</i>₁=0.0410, w<i>R</i>₂ = 0.0749 for 2958 reflections with I&gt; 2ϭ (I). In 5, the quinoxaline ligand coordinates through the ring N(1) atom and the C(8) carbon atom of the carbocyclic ring, whereas in compound <b>6</b>, the ligand coordinates through the ring N(1) atom and the C(2) carbon atom of the heterocyclic ring.