Park-Gehrke Lisa S, Freudenthal John, Kaminsky Werner, Dipasquale Antonio G, Mayer James M
Department of Chemistry, Campus Box 351700, University of Washington, Seattle, WA 98195, USA.
Dalton Trans. 2009 Mar 21(11):1972-83. doi: 10.1039/b820839e. Epub 2009 Jan 29.
CpIrCl(2) () and new CpIr(III)(L-L)X complexes (L-L = N-O or C-N chelating ligands; X = Cl, I, Me) have been prepared and their reactivity with two-electron chemical oxidants explored. Reaction of with PhI(OAc)(2) in wet solvents yields a new chloro-bridged dimer in which each of the Cp ligands has been singly acetoxylated to form Cp(OAc)Ir(III)Cl(2) () (Cp(OAc) = eta(5)-C(5)Me(4)CH(2)OAc). Complex and related carboxy- and alkoxy-functionalized Cp(OR) complexes can also be prepared from plus (PhIO)(n) and ROH. Cp(OAc)Ir(III)Cl(2) () and the methoxy analogue Cp(OMe)Ir(III)Cl(2) () have been structurally characterized. Treatment of CpIrCl(2) () with 2-phenylpyridine yields CpIr(III)(ppy)Cl () (ppy = cyclometallated 2-phenylpyridyl) which is readily converted to its iodide and methyl analogues CpIr(III)(ppy)I and CpIr(III)(ppy)Me (). CpIr(III) complexes were also prepared with N-O chelating ligands derived from anthranilic acid (2-aminobenzoic acid) and alpha-aminoisobutyric acid (H(2)NCMe(2)COOH), ligands chosen to be relatively oxidation resistant. These complexes and were reacted with potential two-electron oxidants including PhI(OAc)(2), hexachlorocyclohexadienone (C(6)Cl(6)O), N-fluoro-2,4,6-trimethylpyridinium (Me(3)pyF(+)), [Me(3)O]BF(4) and MeOTf (OTf = triflate, CF(3)SO(3)). Iridium(V) complexes were not observed or implicated in these reactions, despite the similarity of the potential products to known CpIr(V) species. The carbon electrophiles [Me(3)O]BF(4) and MeOTf appear to react preferentially at the N-O ligands, to give methyl esters in some cases. Overall, the results indicate that Cp is not inert under oxidizing conditions and is therefore not a good supporting ligand for oxidizing organometallic complexes.
已制备出[CpIrCl₂]₂（ ）以及新型的CpIr(III)(L-L)X配合物（L-L = N-O或C-N螯合配体；X = Cl、I、Me），并探索了它们与双电子化学氧化剂的反应活性。在湿溶剂中， 与PhI(OAc)₂反应生成一种新的氯桥联二聚体，其中每个Cp配体都被单乙酰氧基化，形成[Cp(OAc)Ir(III)Cl₂]₂（ ）（Cp(OAc) = η⁵-C₅Me₄CH₂OAc）。配合物以及相关的羧基和烷氧基官能化的Cp(OR)配合物也可以由 与(PhIO)ₙ和ROH制备得到。[Cp(OAc)Ir(III)Cl₂]₂（ ）和甲氧基类似物[Cp(OMe)Ir(III)Cl₂]₂（ ）已通过结构表征。用2-苯基吡啶处理[CpIrCl₂]₂（ ）得到CpIr(III)(ppy)Cl（ ）（ppy = 环金属化的2-苯基吡啶基），它很容易转化为其碘化物和甲基类似物CpIr(III)(ppy)I和CpIr(III)(ppy)Me（ ）。还制备了含有由邻氨基苯甲酸（2-氨基苯甲酸）和α-氨基异丁酸（H₂NCMe₂COOH）衍生的N-O螯合配体的CpIr(III)配合物，选择这些配体是为了具有相对抗氧化性。这些配合物 与包括PhI(OAc)₂、六氯环己二烯酮（C₆Cl₆O）、N-氟-2,4,6-三甲基吡啶鎓（Me₃pyF⁺）、[Me₃O]BF₄和MeOTf（OTf = 三氟甲磺酸盐，CF₃SO₃）在内的潜在双电子氧化剂反应。尽管潜在产物与已知的CpIr(V)物种相似，但在这些反应中未观察到或涉及铱(V)配合物。碳亲电试剂[Me₃O]BF₄和MeOTf似乎优先在N-O配体处反应，在某些情况下生成甲酯。总体而言，结果表明Cp在氧化条件下并非惰性，因此对于氧化有机金属配合物而言不是一个好的支撑配体。
