The Phenomenon of Conglomerate Crystallization. XXII. Synthesis and Structural Characteristics of H-Carbonato(O,O')-trans-[CO(2,3,2-tet)(NO2)]2Cl2.3H2O
Titel:
The Phenomenon of Conglomerate Crystallization. XXII. Synthesis and Structural Characteristics of H-Carbonato(O,O')-trans-[CO(2,3,2-tet)(NO2)]2Cl2.3H2O
Auteur:
Cetrullo, James Bernal, Ivan
Verschenen in:
Journal of coordination chemistry
Paginering:
Jaargang 23 (1991) nr. 1-4 pagina's 257-268
Jaar:
1991-06-01
Inhoud:
The unique, dinuclear, symmetrically μ-CO3 bridged compound, μ-carbonato(O,O')-trans-[Co(2,3,2-tet)-(NO2)]2C12.3H2O (I), was prepared by hydrogen peroxide oxidation of Co+2 in the presence of the 2,3,2-tet polyamine ligand, followed by addition of NaNO2. (I) crystallizes in the racemic space group P21/n with cell constants a = 9.187(1) Å, b = 23.520(2), c = 14.201(1), β = 103.87(9), V= 2978.90 Å3 and d(Z = 4 mol/cell) = 1.599 g cm-3. Data were collected in the range 4° ≤ 20 ≤ 50°, for a total of 5361 reflections, of which 3285 were independent and had I ≥ 3σ(I). These were used in the solution and refinement of the structure. The F(hkl)abs were corrected for absorption (μ = 13.540 cm-1) using Psi scan curves of eight suitable reflections, leading to transmission coefficient adjustments ranging from 0.9049 to 0.9967. The structure was solved by Patterson methods. Convergence of the refinement using anisotropic thermal parameters for the heavy atoms and idealized hydrogens (fixed B = 5.00 Å2) gave R(F) = 0.0510 and Rw (F) = 0.0686. The molecule consists of two [trans-Co(2,3,2-tet)(NO2)] fragments which are nearly perfect mirror images of each other. These are linked by a symmetric [(μ-CO3)] bridge having two independent Co-C bonds of Col-O5 = 1.917(2) and Co2-O6 = 1.911(2) Å. The third oxygen of the CO3- bridge forms two short hydrogen bonds (1.919 and 1.988 Å) with a terminal -NH2 hydrogen from each of the two adjacent polyamine ligands. The C-O distances of the bridging oxygens are, respectively, 1.291(3) and 1.229(3) Å in length. That of the unique C-O is 1.277(3), which fits the expectations of multiple bonding for this oxygen; yet, its length also reflects the multiple hydrogen bonding of this oxygen. The significance of this coordination mode (bridge bonding to metal and to adjacent ligands through hydrogen bonding) of the carbonato ligand may be established by its being an interesting model compound for biological species in which the metal is surrounded by -NH or -OH containing ligands to which the non-coordinating carbonato oxygen can be anchored.
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