Schibli Roger, Marti Niklaus, Maurer Patrick, Spingler Bernhard, Lehaire Marie-Line, Gramlich Volker, Barnes Charles L
Center for Radiopharmaceutical Science, ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
Inorg Chem. 2005 Feb 7;44(3):683-90. doi: 10.1021/ic049599k.
This work describes new synthetic routes to produce mixed carbonyl-nitrosyl complexes of technetium(I) and rhenium(I) in aqueous media. NaNO2, NOHSO4, and NO2(g) have been used to produce in situ nitrous acid as the primary source of NO+. Starting from the organometallic precursor fac-[MX3(CO)3]+, 1 (M = 99Tc, Re; X = Cl, Br), the formation of mixed dicarbonyl-mononitrosyl complexes was observed in aqueous hydrochloric and hydrobromic acid. Time-dependent analyses of the reactions by means of HATR-IR and 99Tc NMR spectroscopy in solution revealed the almost quantitative substitution of one CO ligand by NO+ and, thus, the formation of complexes with facial arrangement of the three pi-acceptor ligands. In the case of technetium, the monomeric complex (NEt4)[TcCl3(CO)2NO] (3a) and the dimeric, chloride-bridged, neutral complex [TcCl(mu-Cl)(CO)2NO]2 (4a) were produced. In the case of rhenium, the monomeric species (NEt4)[ReBr2X(CO)2NO] (X = Br (3b), NO3 (5)) was solely isolated. The X-ray structure of complexes 4a and 5 are discussed. The crystallographic analyses revealed the coordination of the NO+ group trans to the terminal chloride (4a) or the bromide (5), respectively. Crystal data: complex 4a (C4Cl4N2O(6)Tc2), monoclinic, Cc, a = 18.82(3) A, b = 6.103(6) A, c = 12.15(2) A, alpha = 90 degrees , beta = 105.8(2) degrees , gamma = 90 degrees , V = 1343(3) A(3), Z = 4; complex 5 (C10H20N3O(6)Br2Re), orthorhombic, P2(1)2(1)2(1), a = 10.2054(5) A, b = 12.5317(7) A, c = 13.9781(7) A, V = 1787.67(16) A(3), Z = 4. The isolated complexes and their potential facial isomers have been further investigated by density functional theory (DFT) calculations. The energy differences of the isomers are relatively small; however, the calculated energies are consistent with the formation of the observed and isolated compounds. The calculated bond lengths and angles of complex 5 are in good agreement with the data determined by X-ray diffraction. Experiments on the no-carrier-added level starting from fac-[99mTc(H2O)3(CO)3]+ revealed the formation of the complex fac-[99mTcCl(H2O)2(CO)2NO]+ in reasonable good yields. This aqueous-based, synthetic approach will enable the future evaluation of this novel, low-valent metal precursor for potential use in radiopharmacy.
这项工作描述了在水介质中制备锝（I）和铼（I）的混合羰基 - 亚硝酰配合物的新合成路线。已使用亚硝酸钠、硫酸氢羟胺和二氧化氮气体原位生成亚硝酸作为亚硝酰阳离子（NO⁺）的主要来源。从有机金属前体 fac - [MX₃(CO)₃]⁺，1（M = ⁹⁹Tc，Re；X = Cl，Br）出发，在盐酸和氢溴酸水溶液中观察到了混合二羰基 - 单亚硝酰配合物的形成。通过溶液中的HATR - IR和⁹⁹Tc NMR光谱对反应进行时间依赖性分析，结果表明一个CO配体几乎被NO⁺定量取代，从而形成了具有三个π受体配体面式排列的配合物。对于锝，生成了单体配合物（NEt₄）[TcCl₃(CO)₂NO]（3a）和二聚体、氯桥连的中性配合物[TcCl(μ - Cl)(CO)₂NO]₂（4a）。对于铼，仅分离出了单体物种（NEt₄）[ReBr₂X(CO)₂NO]（X = Br（3b），NO₃（5））。讨论了配合物4a和5的X射线结构。晶体学分析表明，NO⁺基团分别与末端氯（4a）或溴（5）呈反位配位。晶体数据：配合物4a（C₄Cl₄N₂O₆Tc₂），单斜晶系，Cc，a = 18.82(3) Å，b = 6.103(6) Å，c = 12.15(2) Å，α = 90°，β = 105.8(2)°，γ = 90°，V = 1343(3) ų，Z = 4；配合物5（C₁₀H₂₀N₃O₆Br₂Re），正交晶系，P2₁2₁2₁，a = 10.2054(5) Å，b = 12.5317(7) Å，c = 13.9781(7) Å，V = 1787.67(16) ų，Z = 4。通过密度泛函理论（DFT）计算对分离得到的配合物及其可能的面式异构体进行了进一步研究。异构体的能量差异相对较小；然而，计算得到的能量与观察到的和分离得到的化合物的形成情况一致。配合物5的计算键长和键角与X射线衍射测定的数据吻合良好。从fac - [⁹⁹mTc(H₂O)₃(CO)₃]⁺开始的无载体添加水平实验表明，以相当高的产率生成了配合物fac - [⁹⁹mTcCl(H₂O)₂(CO)₂NO]⁺。这种基于水相的合成方法将使未来能够评估这种新型低价金属前体在放射性药物学中的潜在用途。
