A Highly Distorted Open-Shell Endohedral Zintl Cluster: [Mn@Pb12]3鈥?/sup>

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• 作者：Binbin Zhou ; Tobias Kra虉mer ; Amber L. Thompson ; John E. McGrady ; Jose M. Goicoechea
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：September 5, 2011
• 年：2011
• 卷：50
• 期：17
• 页码：8028-8037
• 全文大小：1081K
• 年卷期：v.50,no.17(September 5, 2011)
• ISSN：1520-510X

文摘

Reaction of an ethylenediamine (en) solution of K₄Pb₉ and 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) with a tetrahydrofuran (THF) solution of Mn₃(Mes)₆ (Mes = 2,4,6-trimethylphenyl) yielded the anionic cluster [Mn@Pb₁₂]^{3鈥?/sup>. This species was observed in the positive and negative ion-mode electrospray mass-spectra of the crude reaction mixture. The crystalline samples obtained from such solutions allowed us to confirm the composition of the sample as [K(2,2,2-crypt)]₃[Mn@Pb₁₂]路1.5en (1). Because of numerous issues related to crystal sample quality and crystallographic disorder a high-quality crystal structure solution could not be obtained. Despite this, however, the data collected permit us to draw reasonable conclusions about the charge and connectivity of the [Mn@Pb₁₂]3鈥?/sup> cluster anion. Crystals of 1 were further characterized by elemental analysis and electron paramagnetic resonance (EPR). Density Functional Theory (DFT) calculations on such a system reveal a highly distorted endohedral cluster anion, consistent with the structural distortions observed by single crystal X-ray diffraction. The cluster anions are considerably expanded compared to the 36-electron closed-shell analogue [Ni@Pb₁₂]2鈥?/sup> and, moreover, exhibit significant low-symmetry distortions from the idealized icosahedral (I_h) geometry that is characteristic of related endohedral clusters. Our computations indicate that there is substantial transfer of electron density from the formally Mn(鈭扞) center to the low-lying vacant orbitals of the [Pb₁₂]2鈥?/sup> cage.}