Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA.
J Am Soc Mass Spectrom. 2010 May;21(5):739-49. doi: 10.1016/j.jasms.2010.01.022. Epub 2010 Jan 28.
Manganese carbonyl cations of the form Mn(CO)(n)(+) (n = 1-9) are produced in a molecular beam by laser vaporization in a pulsed nozzle source. Mass selected infrared photodissociation spectroscopy in the carbonyl stretching region is used to study these complexes and their "argon-tagged" analogues. The geometries and electronic states of these complexes are determined by comparing their infrared spectra to theoretical predictions. Mn(CO)(6)(+) has a completed coordination sphere, consistent with its predicted 18-electron stability. It has an octahedral structure in its singlet ground state, similar to its isoelectronic analogue Cr(CO)(6). Charge-induced reduction in pi back-bonding leads to a decreased red-shift in Mn(CO)(6)(+) (upsilon(CO) = 2106 cm(-1)) compared with Cr(CO)(6) (upsilon(CO) = 2003 cm(-1)). The spin multiplicity of Mn(+)(CO)(n) complexes gradually decreases with progressive ligand addition. MnCO(+) is observed as both a quintet and a septet, Mn(CO)(2)(+) is observed only as a quintet, while Mn(CO)(3,4)(+) are both observed as triplets. Mn(CO)(5)(+) and Mn(CO)(6)(+) are both singlets, as are all larger complexes.
形式为 Mn(CO)(n)(+) (n = 1-9) 的锰羰基阳离子是通过激光蒸发在脉冲喷嘴源中在分子束中产生的。在羰基伸缩区域中使用质量选择的红外光解光谱学来研究这些配合物及其“氩标记”类似物。通过将它们的红外光谱与理论预测进行比较，确定了这些配合物的几何形状和电子状态。Mn(CO)(6)(+) 具有完整的配位球，与其预测的 18 电子稳定性一致。它在其单重基态下具有八面体结构，类似于其等电子类似物 Cr(CO)(6)。由于电荷诱导导致π反键减少，与 Cr(CO)(6)（ν(CO) = 2003 cm(-1)）相比，Mn(CO)(6)(+) 的红移减小（ν(CO) = 2106 cm(-1)）。Mn(+)(CO)(n) 配合物的自旋多重度随着配体的逐步添加而逐渐降低。MnCO(+) 被观察到既是五重态又是七重态，Mn(CO)(2)(+) 仅被观察到是五重态，而 Mn(CO)(3,4)(+) 都被观察到是三重态。Mn(CO)(5)(+) 和 Mn(CO)(6)(+) 都是单重态，所有更大的配合物也是如此。
