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Three-Coordiante [Cu~(II)X_3]~- (X=Cl, Br), Trapped in a Molecular Crystal

机译:困在分子晶体中的三Coordiante [Cu〜(II)X_3]〜-(X = Cl,Br)

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摘要

Mixtures of [Ph_3PNPPh_3]~+Cl~- with CuBr_2 (or CuBr_2+CuCl_2) in ethanol/dichloromehane yield crystals containing three-coordinate copper(II) with mixed chloride and bromide ligands, namely [Ph_3PNPPh_3]~+[CuCl_(0.9)Br_(2.1)]~- (1) and [Ph_3PNPPh_3]~+[CuCl_(2.4)Br_(0.6)]~- (2). The trigonal-planar coordination of copper(II) is angularly distorted but unambiguous, as there is not other halide ligand within 6.7 A of the copper atom. Density functionaly theory (DFT) calculatins on planar [CuClBr_2]~- show that the energy surface for angle bending is very soft. crystallisation in the presence of CH_3CN yields [Ph_3PNPPh_3]~+[CuCl_(0.7)Br_(2.3)(NCCH_3)]~- (3), in which there is additional secondary coordination by NCCH_3 (Cu-N 2.44 A). DFT calculations of the potential energy surface for this secondary coordiantion show that it is remarkeably flat (<3 kcal mol~(-1) for a variation of Cu-N by 0.8 A). The crystla packing in 1, 2 and 3, which involves multiple phenyl embraces between [Ph_3PNPPh_3]~+ ions and numerous C-H…Br motifs, is associated with intrmolecular energies that are larger than the variations in intramolecular enenergies. For reference, the crystla sturctures of [PhPNPPh_3~+]_2[Cu_2Cl_6]~(2-) (4) and [Ph_3PNPPh_3~+]_(2[CuBr_6]~(2-) (5) are described. We conclude 1) that three-coordinate copper(II) with monatomic halide ligands, although uncommon, can be regarded as normal, 2) that steric control by ligands is not necessary to enforce three-coordiantion, 3) that a hydrophobic aryl environment stabilises [Cu(Cl/Br)_3]~-, and 4) that the energy change in the transition from three-to four-coordinate copper(II) is very small (ca 5 kcal mol~(-1)).
机译:[Ph_3PNPPh_3]〜+ Cl〜-与CuBr_2(或CuBr_2 + CuCl_2)在乙醇/二氯甲烷中的混合物产生的晶体含有三配位铜(II),具有氯化物和溴化物配体,即[Ph_3PNPPh_3]〜+ [CuCl_(0.9) Br_(2.1)]〜-(1)和[Ph_3PNPPh_3]〜+ [CuCl_(2.4)Br_(0.6)]〜-(2)。铜(II)的三角平面配位在角度上是扭曲的,但是明确的,因为在铜原子的6.7 A之内没有其他卤化物配体。平面[CuClBr_2]〜-上的密度泛函理论(DFT)计算表明,角弯曲的能量表面非常柔软。在CH_3CN存在下结晶可得到[Ph_3PNPPh_3]〜[CuCl_(0.7)Br_(2.3)(NCCH_3)]〜-(3),其中还有NCCH_3(Cu-N 2.44 A)进行的二次配位。二次坐标的势能面的DFT计算表明,它非常平坦(对于Cu-N的0.8 A变化,<3 kcal mol〜(-1))。在1、2和3中的晶体填充,涉及[Ph_3PNPPh_3]〜+离子之间的多个苯基包围和许多C-H…Br基序,与分子内能量相关,该分子内能量大于分子内能量的变化。作为参考,描述了[PhPNPPh_3〜+] _ 2 [Cu_2Cl_6]〜(2-)(4)和[Ph_3PNPPh_3〜+] _(2 [CuBr_6]〜(2-)(5)的晶体结构,得出结论1。 )具有单原子卤化物配体的三配位铜(II),尽管不常见,但可以认为是正常现象; 2)通过配体的空间控制对于强制三配位是不必要的; 3)疏水性芳基环境可以稳定[Cu( Cl / Br)_3]-,和4)从三到四配位铜(II)的跃迁中的能量变化很小(约5kcal mol〜(-1))。

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