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Dr. Benedict M. Gardner Dr. Floriana Tuna Prof. Eric J. L. McInnes Dr. Jonathan McMaster Dr. William Lewis Prof. Alexander J. Blake Prof. Stephen T. Liddle 《Angewandte Chemie (International ed. in English)》2015,54(24):7068-7072
Reaction of [U(TrenTIPS)] [ 1 , TrenTIPS=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo‐P5 complex [{U(TrenTIPS)}2(μ‐η5:η5‐cyclo‐P5)] ( 2 ). All prior examples of cyclo‐P5 are stabilized by d‐block metals, so 2 shows that cyclo‐P5 does not require d‐block ions to be prepared. Although cyclo‐P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ‐ and π‐interactions with minimal δ‐bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ‐bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo‐P5 unit to give a cyclo‐P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo‐P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ‐symmetry 5f orbitals. 相似文献
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The reaction of (η5-cyclopentadienyl)(η4-1,3-diphenylcyclobutadiene)cobalt ( I ) with excess Cr(CO)3py3 in BF3OEt2 yielded two identified heterometallic compounds. Compounds II and III with one and two phenyl rings complcxed with Cr(CO)3 fragment(s), respectively. These compounds were characterized by mass, infrared, 1H and 13C NMR spectra and elemental analysis. The crystal structure of II was determined. The Cr(CO)3 fragment bends inward toward the cyclobutadicne ring due to its electron-withdrawing ability, in accord with Hunter's postulate. A sharp line due to the non-complexed phenyl ring was observed in the 1HNMR spectrum, which implies that five protons are magnetically equivalent. The chemical shifts of two protons of the cyclobutadiene ring decreased from I to II then to III , possibly because of diminished deshielding effect from the phenyl ring in (arene)Cr(CO)3. 相似文献
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