Gourlay Craig, Nielsen David J, Evans David J, White Jonathan M, Young Charles G
School of Chemistry , University of Melbourne , Victoria 3010 , Australia.
Bio21 Molecular Science and Biotechnology Institute , University of Melbourne , Victoria 3010 , Australia.
Chem Sci. 2017 Nov 20;9(4):876-888. doi: 10.1039/c7sc04239f. eCollection 2018 Jan 28.
Reaction of [CoCp][TpMoOS(OAr)] [Cp = η-cyclopentadienyl; Tp = hydrotris(3-isopropylpyrazol-1-yl)borate; OAr = phenolate or derivative thereof] with [Cu(NCMe)(Metcn)]BF (Metcn = 1,4,7-trimethyl-1,4,7-triazacyclononane) in MeCN at -30 °C results in the formation of red-brown/black, paramagnetic, μ-sulfido-Mo(v)/Cu(i) complexes, TpMoO(OAr)(μ-S)Cu(Metcn). The complexes possess the MoO(μ-S)Cu core found in aerobic carbon monoxide dehydrogenases (CODHs) and exhibit X-band EPR spectra closely related to those of semi-reduced CODH, with ∼ 1.937, hyperfine coupling to Mo ( = 39-42 × 10 cm) and strong superhyperfine coupling to Cu ( = 34-63 × 10 cm). Anisotropic spectra exhibit monoclinic symmetry with ∼ 1.996, ∼ 1.944 and ∼ 1.882, and nearly isotropic values (75-90 × 10 cm). The X-ray structures of four derivatives (Ar = Ph, CH Bu-2, CH Bu-2, CHPh-4) are reported and discussed along with that of the Ar = CH Bu-3,5 derivative (communicated in C. Gourlay, D. J. Nielsen, J. M. White, S. Z. Knottenbelt, M. L. Kirk and C. G. Young, , 2006, , 2164). The complexes exhibit distorted octahedral oxo-Mo(v) and distorted tetrahedral Cu(i) centres bridged by a single bent μ-sulfido ligand, with Mo-S and Cu-S distances and Mo-S-Cu angles in the ranges 2.262-2.300 Å, 2.111-2.134 Å and 115.87-134.27°, respectively. The 2 -butyl derivative adopts a unique phenolate conformation with O[double bond, length as m-dash]Mo-O-Cα and O[double bond, length as m-dash]Mo-S-Cu torsion angles of 92.7 and 21.1°, respectively, very different from those of the other structurally characterized derivatives (31-47 and 33-45°, respectively) and exhibits a relatively short Mo···Cu distance [3.752(2) Å 3.806(7)-4.040(2) Å]. As well, the value of this complex (34.3 × 10 cm) is much lower than the values observed for other members of the series (55-63 × 10 cm), supporting the hypothesis that the electronic structure of the MoO(μ-S)Cu core unit and the degree of intermetallic communication are strongly dependent on the geometry of the MoO(OR)(μ-S)Cu unit. The complexes participate in an electrochemically reversible Mo(vi)/Mo(v) redox couple and react with cyanide undergoing decupration and desulfurization reactions of the type observed for CODH.
[CoCp][TpMoOS(OAr)]（Cp = η-环戊二烯基；Tp = 氢三（3-异丙基吡唑-1-基）硼酸酯；OAr = 酚盐或其衍生物）与[Cu(NCMe)(Metcn)]BF（Metcn = 1,4,7-三甲基-1,4,7-三氮杂环壬烷）在乙腈中于-30°C反应，生成红棕色/黑色的顺磁性μ-硫代-Mo(V)/Cu(I)配合物TpMoO(OAr)(μ-S)Cu(Metcn)。这些配合物具有在好氧一氧化碳脱氢酶（CODHs）中发现的MoO(μ-S)Cu核心，并且呈现出与半还原CODH的X波段电子顺磁共振（EPR）光谱密切相关的光谱，g约为1.937，与Mo的超精细耦合（A = 39 - 42×10⁻⁴ cm⁻¹）以及与Cu的强超超精细耦合（A = 34 - 63×10⁻⁴ cm⁻¹）。各向异性光谱呈现单斜对称性，g₁约为1.996，g₂约为1.944，g₃约为1.882，并且具有近乎各向同性的g值（75 - 90×10⁻⁴ cm⁻¹）。报道并讨论了四种衍生物（Ar = Ph、CH₂Bu-2、CH₂Bu-2、CHPh-4）以及Ar = CH₂Bu-3,5衍生物（发表于C. Gourlay、D. J. Nielsen、J. M. White、S. Z. Knottenbelt、M. L. Kirk和C. G. Young，Angew. Chem. Int. Ed.，2006，45，2164）的X射线结构。这些配合物呈现出扭曲的八面体氧代-Mo(V)和扭曲的四面体Cu(I)中心，由单个弯曲的μ-硫代配体桥连，Mo-S和Cu-S距离以及Mo-S-Cu角度分别在2.262 - 2.300 Å、2.111 - 2.134 Å和115.87 - 134.27°范围内。2-丁基衍生物采用独特的酚盐构象，O[双键，长度如m破折号]Mo-O-Cα和O[双键，长度如m破折号]Mo-S-Cu扭转角分别为92.7°和21.1°，与其他结构表征的衍生物（分别为31 - 47°和33 - 45°）非常不同，并且呈现出相对较短的Mo···Cu距离[3.752(2) Å，3.806(7) - 4.040(2) Å]。同样，该配合物的A值（34.3×10⁻⁴ cm⁻¹）远低于该系列其他成员观察到的值（55 - 63×10⁻⁴ cm⁻¹），支持了MoO(μ-S)Cu核心单元的电子结构和金属间通讯程度强烈依赖于MoO(OR)(μ-S)Cu单元几何形状的假设。这些配合物参与电化学可逆的Mo(VI)/Mo(V)氧化还原对，并与氰化物反应，发生CODH所观察到的那种脱铜和脱硫反应。
