Transient palladadiphosphanylcarbenes: singlet carbenes with an "inverse" electronic configuration (p(pi)2 instead of sigma2) and unusual transannular metal-carbene interactions (piC-->Pd donation and sigmaPd-->C back-donation).
Transient palladadiphosphanylcarbenes: singlet carbenes with an "inverse" electronic configuration (p(pi)2 instead of sigma2) and unusual transannular metal-carbene interactions (piC-->Pd donation and sigmaPd-->C back-donation).
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瞬态钯二膦基卡宾：具有“逆”电子构型（p(pi)2 而不是 sigma2）的单线态卡宾和不寻常的跨环金属卡宾相互作用（piC-->Pd 供体和 sigmaPd-->C 反供体）。
DOI：
10.1021/ja066738j
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发表时间：
2007
影响因子：
15
通讯作者：
Bertrand,Guy
中科院分区：
文献类型：
--
作者：
Vignolle,Joan;Gornitzka,Heinz;Maron,Laurent;Schoeller,WolfgangW;Bourissou,Didier;Bertrand,Guy
在用[PdCl（allyl）]2处理时，不对称取代的α，α ′-二膦基重氮化合物消除二氮，以高产率提供C-氯二膦基甲烷络合物。在氯化物提取剂如四苯硼钠存在下，C-氯代二膦酰甲烷配合物与吡啶和三甲基膦反应，容易得到相应的氮和磷叶立德。在这一过程中，假定的中间体，即palladiphosphanylcarbenes，不能进行光谱表征，但其瞬时形成的化学支持进一步由吡啶和4-二甲氨基吡啶之间的刘易斯碱交换反应。这一假设也得到了证实，通过计算相应的解离能使用两个模型系统具有甲基基团的磷。特别有趣的是，密度泛函理论计算显示，这些palladiphosphanylcarbenes有一个单重态基态，具有“反”pπ 2电子构型和与不寻常的跨环金属-卡宾相互作用（πC→ Pddonion和σPd→Cback-donation）相关的扭曲几何结构。
Upon treatment with [PdCl(allyl)]2, asymmetrically substituted α,α‘-diphosphanyl diazo compounds eliminate dinitrogen to affordC-chlorodiphosphanylmethanide complexes in high yields. In the presence of a chloride-abstracting agent, such as sodium tetraphenylborate, theC-chlorodiphosphanylmethanide complexes react with pyridine and trimethylphosphine, readily affording the corresponding nitrogen and phosphorus ylides. The postulated intermediate in this process, namely palladadiphosphanylcarbenes, could not be spectroscopically characterized, but their transient formation was chemically supported further by a Lewis base exchange reaction between pyridine and 4-dimethylaminopyridine. This hypothesis has also been substantiated by computing the corresponding dissociation energy using two model systems featuring methyl groups at the phosphorus. Of particular interest, density functional theory calculations reveal that these palladadiphosphanylcarbenes have a singlet ground state with an “inverse” pπ2electronic configuration and a distorted geometry associated with unusual transannular metal−carbene interactions (πC→Pddonation and σPd→Cback-donation).