Cyanate groups in higher oxidation state metal cluster chemistry: Mixed-valence (II/III) Mn₁₆ and Mn₁₈ clusters

详细信息    查看全文

• 作者：Dimitris I. Alexandropoulos^a ; Eleni E. Moushi^b ; Constantina Papatriantafyllopoulou^b ; ^c ; Christine M. Beavers^d ; Simon J. Teat^d ; Anastasios J. Tasiopoulos^b ; George Christou^c ; Theocharis C. Stamatatos^a ; ^{tstamatatos@brocku.ca" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Manganese ; Cyanates ; 2-(Hydroxymethyl)pyridine ; Crystal structures ; Magnetism
• 刊名：Polyhedron
• 出版年：2016
• 出版时间：29 March 2016
• 年：2016
• 卷：108
• 期：Complete
• 页码：131-142
• 全文大小：1928 K

文摘

The employment of cyanato (OCN⁻) group in high oxidation state manganese cluster chemistry, in conjunction with carboxylate ions and the organic chelating/bridging ligand 2-(hydroxymethyl)pyridine (hmpH), is reported. The syntheses, crystal structures, and magnetochemical characterization are described for [Mn₁₆O₈(OR)₄(OCN)₄(O₂CMe)₁₂(hmp)₆(ROH)₂] (R = Me (1), Et (2)) and [Mn₁₈O₁₄(O₂CR)₁₈(hmp)₄(hmpH)₂(H₂O)₂] (R = Me (3), Et (4)). The 2:1:1:1 reactions of Mn(O₂CMe)₂·4H₂O, hmpH, NaOCN and NEt₃ in solvent MeOH or EtOH afford the isostructural complexes [Mn₁₆O₈(OR)₄(OCN)₄(O₂CMe)₁₂(hmp)₆(ROH)₂] (R = Me (1), Et (2)). The [Mn₁₆(μ₄-O)₄(μ₃-O)₄(μ-OMe)₄(μ₃-OR)₆(μ-OR)₆]¹⁰⁺ core of representative complex 1 comprises a Mn^II₄Mn^III₄ double-cubane subunit attached on either side to two symmetry-related Mn^IIMn^III₃ defective dicubanes. A similar reaction of Mn(O₂CR)₂·4H₂O, hmpH, NaOCN and NEt₃, but in solvent MeCN, led instead to the formation of [Mn₁₈O₁₄(O₂CR)₁₈(hmp)₄(hmpH)₂(H₂O)₂] (R = Me (3), Et (4)). Compounds 3 and 4 are very similar to each other and can be described as a central [Mn^III₄(μ-O)₆] rodlike subunit attached on either side to two symmetry-related [Mn₇O₉] subunits. Variable-temperature, solid-state dc and ac magnetic susceptibility studies revealed the presence of predominant antiferromagnetic exchange interactions in all compounds, and possible S = 2 or 1 (for 1 and 2) and S = 0 (for 3 and 4) ground state spin values. The combined results demonstrate the ability of cyanato groups to facilitate the formation of new polynuclear Mn^II/III complexes with structures different than these obtained from the use of the related azides.