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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Coordination chemistry of phosphanyl amino acids:solid state and solution structures of neutral and cationic rhodium complexes
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Coordination chemistry of phosphanyl amino acids:solid state and solution structures of neutral and cationic rhodium complexes

机译：膦酰基氨基酸的配位化学：中性和阳离子铑配合物的固态和溶液结构

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Copper phosphide or arsenide complexes,[Cu(EPh_2)(neo)](E = P,As,neo = 2,9-dimethyl-1,10-phenanthroline;trivial name:neocuprine)react selectively with the N-protected brominated serine derivatives,2-(S)-(alkoxycarbonylamino)-3-bromomethylpropionates 1a-c(~(ROCO)SerBr,a:R = PhCH_2,b:tBu,c:Me)to give the corresponding phosphanylated or arsanylated amino acids,~(ROCO)SerPhos(3a-c:Phos = PPh_2)and ~zSerArs 7(Ars = AsPh_2,Z = PhCH_2OCO).The dipeptide ~zAlaSerPhos 3d was likewise prepared.The phosphanes 3a-d,and the arsane 7 reacted cleanly with [Rh_2(mu-Cl)_2(cod)_2] to give the rhodium(I)complexes [RHCl(cod)(~zSerPhos)] 8,[RHCl(cod)(~(Boc)SerPhos)] 9(Boc = tBuOCO),[RHCl(cod)(~zAlaSerPhos)] 10,and [RHCl(cod)(~zSerArs)] 11 which were characterized by X-ray diffraction studies.A common structural feature is an intramolecular(II)H...Cl(Rh)-hydrogen bridge which according to NMR investigations remains intact in solution.The abstraction of chloride from the coordination sphere of Rh(I)in 8 or 10 has a profound structural impact.While in 8 and 10,the ligands bind in a monodentate fashion,via the phosphorus atom only,they serve as bidentate ligands via the phosphorus centre and the peptidic C=O group in [Rh(cod)(kappa~2-~zSerPhos)]PF_6 12 and [Rh(cod)(kappa~2-~zAlaSerPhos)]PF_6 13.This causes also the amino acid residue structures to change from alpha-helix type in 8 and 10 to a beta-sheet type in 12 and 13.Addition of chloride to 12 and 13 fully re-establishes the structures of 8 and 10.The complexes [RHCl(cod)(~zSerPhos)] 8 and [RHCl(cod)-(~(Boc)SerPhos)] 9 show good activities in homogeneously catalyzed hydrogenations of olefins while the dipeptide complex 10 is less active.Phosphane addition to 8 greatly diminishes the catalytic activity.The cationic complex [Rh(cod)(kappa~2-~zAlaSerPhos)]PF_6 shows low activity which,however,is greatly increased by addition of one equivalent of phosphane.
机译：磷化铜或砷化物络合物，[Cu（EPh_2）（neo）]（E = P，As，neo = 2,9-二甲基-1,10-菲咯啉;简称：neupuproline）与N保护的溴化丝氨酸选择性反应衍生物，2-（S）-（烷氧基羰基氨基）-3-溴甲基丙酸酯1a-c（〜（ROCO）SerBr，a：R = PhCH_2，b：tBu，c：Me）得到相应的膦酰基化或砷基化的氨基酸（ROCO）SerPhos（3a-c：Phos = PPh_2）和〜zSerArs 7（Ars = AsPh_2，Z = PhCH_2OCO）。同样制备了二肽〜zAlaSerPhos 3d。膦3a-d和the 7与[ Rh_2（mu-Cl）_2（cod）_2]生成铑（I）络合物[RHCl（cod）（〜zSerPhos）] 8，[RHCl（cod）（〜（Boc）SerPhos）] 9（Boc = tBuOCO ），[RHCl（cod）（〜zAlaSerPhos）] 10和[RHCl（cod）（〜zSerArs）] 11由X射线衍射研究表征。一个常见的结构特征是分子内（II）H ... Cl（Rh）-氢桥，根据NMR研究在溶液中保持完整。在8或10中从Rh（I）的配位球中提取氯离子具有深远的结构影响。在8和10中，配体仅通过磷原子以单齿方式结合，它们通过[Rh（cod）（kappa）中的磷中心和肽C = O基团作为双齿配体〜2-〜zSerPhos）] PF_6 12和[Rh（cod）（kappa〜2-〜zAlaSerPhos）] PF_613。这也导致氨基酸残基结构从8和10中的α-螺旋类型变为β-在12和13中为片状类型。向12和13中添加氯离子可完全重建8和10的结构。络合物[RHCl（cod）（〜zSerPhos）] 8和[RHCl（cod）-（〜（Boc）） [SerPhos）] 9在均相催化的烯烃加氢中显示出良好的活性，而二肽配合物10的活性较低。向8中添加磷显着降低了催化活性。阳离子配合物[Rh（cod）（kappa〜2-〜zAlaSerPhos）] PF_6具有低活性，但是通过加入一当量的膦大大提高了活性。

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