The synthesis and characterisation of the trinuclear Ni–Fe complex [Ni(L2)SFe2(CO)6] (1) formed from the reaction of [Ni(L1)] with Fe3(CO)12 is described. The single-crystal X-ray structure of 1 shows Ni(II) bound to three thioether R2-S donors and bridged by a sulfide (S2−) group to two Fe(CO)3 units. 1 undergoes a reversible one-electron reduction process at E1/2 = −1.62 V vs. Fc+/Fc to generate 1−, which has been characterised by UV-vis and IR spectroelectrochemistry and by EPR spectroscopy. DFT calculations on 1 and 1− reveal electronic structures that are delocalised across the NiFe2 core. The SOMO in 1− possesses Ni–Fe and Fe–Fe anti-bonding character and lies approximately in the plane defined by the equilateral triangle of Ni and Fe atoms. It possesses d-orbital contributions of 18.5, 15.0 and 19.8% for the Ni(1), Fe(1) and Fe(2) atoms, respectively. The Ni–S(sulfide) bond length in 1 [2.1654(7) Å] is identical to that for the bridging sulfide found in the oxidised inactive form of the [NiFe] hydrogenase from D. vulgaris (2.16 Å). Thus, 1 provides a useful comparison for biological [NiFe] centres bridged by sulfide donors.
本文介绍了[Ni(L1)]与 Fe3(CO)12 反应生成的三核
镍铁复合物[Ni(
L2)SFe2(CO)6](1)的合成和特性。1 的单晶 X 射线结构显示,Ni(II) 与三个
硫醚 R2-S 给体结合,并通过一个
硫化物 (S2-) 基团与两个 Fe(CO)3 单元桥接。1 在 E1/2 = -1.62 V 对 Fc+/Fc 的条件下经历了一个可逆的单电子还原过程,生成了 1-,并通过紫外-可见光、红外光谱电
化学和 EPR 光谱对其进行了表征。对 1 和 1- 的 DFT 计算显示了整个 NiFe2 内核的电子结构。1- 中的 SOMO 具有
镍-
铁和
铁-
镍反键特性,大致位于
镍原子和
铁原子等边三角形所定义的平面内。
镍(1)、
铁(1)和
铁(2)原子的 d-轨道贡献率分别为 18.5%、15.0% 和 19.8%。1 中的 Ni-S(
硫化物)键长度[2.1654(7) Å]与来自 D. vulgaris 的[NiFe]氢化酶的氧化非活性形式(2.16 Å)中的
硫化物桥键长度相同。因此,1 为
硫化物供体桥接的
生物[NiFe]中心提供了一个有用的比较。