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|Section2= |Section3= |Section7= |Section8= }} Nickelocene is the organonickel compound with the formula Ni(η5-C5H5)2. Also known as bis(cyclopentadienyl)nickel or NiCp2, this bright green paramagnetic solid is of enduring academic interest,〔Elschenbroich, C. ”Organometallics” (2006) Wiley-VCH: Weinheim. ISBN 978-3-527-29390-2〕 although it yet has no practical applications. ==Structure and bonding== Ni(C5H5)2 belongs to a group of organometallic compounds called metallocenes. Metallocenes usually adopt structures in which a metal ion is sandwiched between two parallel cyclopentadienyl (Cp) rings. This structure is relevant to the solubility in organic solvents and volatility. In the solid-state, the molecule has D5h symmetry, wherein the two rings are eclipsed. The Ni center has a formal 2+ charge, and the Cp rings are usually assigned as cyclopentadienyl anions (Cp−), related to cyclopentadiene by deprotonation. The structure is similar to ferrocene. In terms of its electronic structure, three pairs of d electrons on nickel are allocated to the three d orbitals involved in Ni - Cp bonding: dxy, dx2–y2, dz2. One of the two remaining d-electrons resides in each of the dyz and dxz orbitals, giving rise to the molecule's paramagnetism, as manifested in the unusually high field chemical shift observed in its 1H NMR spectrum. With 20 valence electrons, nickelocene has the highest electron count of the transition metal metallocenes. Cobaltocene, Co(C5H5)2, with only 19 valence is, however, a stronger reducing agent, illustrating the fact that electron energy, not electron count determines redox potential. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「nickelocene」の詳細全文を読む スポンサード リンク
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