Combined Theoretical and Experimental Analysis of the Bonding in the Heterobimetallic Cubane-Type Mo3NiS4 and Mo3CuS4 Core Clusters

详细信息    查看全文

• 作者：Juan André ; s ; Marta Feliz ; Jordi Fraxedas ; Victor Herná ; ndez ; Juan T. L&oacute ; pez-Navarrete ; Rosa Llusar ; Guillaume Sauthier ; Fabricio R. Sensato ; Bernard Silvi ; Carles Boand ; Josep M. Cam
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：March 19, 2007
• 年：2007
• 卷：46
• 期：6
• 页码：2159 - 2166
• 全文大小：218K
• 年卷期：v.46,no.6(March 19, 2007)
• ISSN：1520-510X

文摘

X-ray structural data for the cubane-type clusters [Mo₃CuS₄(dmpe)₃Cl₄]⁺ and Mo₃NiS₄(dmpe)₃Cl₄ (dmpe = 1,2-bis(dimethylphosphino)ethane) with 16 metal electrons have been compared with optimized structural parameterscalculated using "ab initio" methodologies. Compound Mo₃NiS₄(dmpe)₃Cl₄ crystallizes in the cubic noncentrosymmetricspace group P2₁3 with a Mo-Ni distance of 2.647 Å, that is 0.2 Å shorter than the Mo-Cu bond length in theisoelectronic copper cluster. The best agreement between theory and experiments has been obtained using theB3P86 method. In order to validate the B3P86 results, accurate infrared and Raman spectra have been acquiredand the vibrational modes associated to the cubane-type Mo₃M'S₄ (M' = Cu or Ni) unit have been assignedtheoretically. The electronic changes taking place when incorporating the M' into the Mo₃S₄ unit have been analyzedfrom a theoretical and experimental perspective. The bond dissociation energies between M'-Cl and Mo₃S₄ fragmentsshow that formation of [Mo₃CuS₄(dmpe)₃Cl₄]⁺ is 135 kcal/mol energetically less favorable than the Ni incorporation.The more robust nature of the Mo₃NiS₄ fragment has been confirmed by mass spectrometry. The X-ray photoelectronspectroscopy (XPS) spectra of the trimetallic and tetrametallic complexes have been measured and the obtainedbinding energies compared with the computed electronic populations based on topological approaches of the electronlocalization function (ELF). The energies and shapes of the Cu 2p and Ni 2p lines indicate formal oxidation statesof Cu(I) and Ni(II). However, the reductive addition of nickel into [Mo₃S₄(dmpe)₃Cl₃]⁺ causes a small decrease inthe Mo 3d binding energies. This fact prevents an unambiguous assignment of an oxidation state in a conventionalway, a circumstance that has been analyzed through the covariance of the electronic populations associated to theC(M') core and V(Mo₃Ni) and V(S(2)') valence basins where Mo₃NiS₄ is a particularly electronically delocalizedchemical entity.