Solitaire and Gemini Metallocene Porphyrazines

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• 作者：Sarah L. J. Michel ; David P. Goldberg ; Charlotte Stern ; Anthony G. M. Barrett ; and Brian M. Hoffman
• 刊名：Journal of the American Chemical Society
• 出版年：2001
• 出版时间：May 23, 2001
• 年：2001
• 卷：123
• 期：20
• 页码：4741 - 4748
• 全文大小：136K
• 年卷期：v.123,no.20(May 23, 2001)
• ISSN：1520-5126

文摘

We report the synthesis and physical characterization of a series of peripherally functionalizedporphyrazines (pzs) of the forms H₂[pz(A;B₃)] and trans-H₂[pz(A₂;B₂)], where A is a dithiolene chelate ofmolybdocene or vanadocene and B is a solublizing group. The precursor pz's 8 and 9, of the form H₂[pz(A;B₃)], where A = (4-(butyloxycarbonyl)-S-benzyl)₂ and B = di-tert-butylphenyl (8) or di-n-propyl (9), havebeen prepared, deprotected, and peripherally metalated with molybdocene and vanadocene to form 1(Mo^IV)and 1(V^IV), prepared from 8, and 2(Mo^IV) from 9, respectively. Likewise, the protected trans-H₂[pz(A₂;B₂)],where A = (S-benzyl)₂ and B = 3,6-butyloxybenzene (12) or A = (S-benzyl)₂ and B = (tert-butylphenyl)₂(13), have been prepared and peripherally metalated with molybdocene and vanadocene to give the transdinuclear complexes, 3(Mo^IV,Mo^IV), 3(V^IV,V^IV) (from 12), and 4(V^IV,V^IV) (from 13). A crystal structure ofthe trans vanadocene pz 4(V^IV,V^IV) is presented; the distance between the two vanadium atoms is 14.5 Å. Themolybdocene-appended pz's are highly redox active and exhibit cyclic voltammograms that are more than justthe sum of the metallocene and the parent pz's. Chemical oxidation with FcPF₆ gives the Mo^V species 1(Mo^V),2(Mo^V), 3(Mo^V,Mo^IV), and 3(Mo^V,Mo^V). Their EPR spectra are indicative of extensive delocalization fromthe Mo^V into the dithiolato-pz. The EPR spectrum of the mononuclear paramagnetic vanadocene pz, 1(V^IV),shows an expected 8-line pattern for an S = 2 system with hyperfine coupling to a single ⁵¹V (I = ⁷/₂) nucleus,but the dinuclear vanadocene pz's, 3(V^IV,V^IV) and 4(V^IV,V^IV), exhibit a striking 15-line pattern of the samebreadth from the S = 1 state formed by exchange coupling between the S = 2 vanadium centers of a dinuclearcomplex. Thus, the porphyrazine macrocycle is capable of mediating magnetic exchange interactions betweenmetal ions bound to the periphery, separated by 14.5 Å.