調控不對稱異核金屬串的立體化學構型：CuCuM (M = Pd or Pt)化合物的合成與物理性質研究

Abstract

本篇論文主要討論不對稱異核金屬串化合物(4,0)-[CuCuML4X][anion]的合成、結構、光譜、磁性和理論研究 (M 為鈀或鉑離子，L 為不對稱配基，軸向配基X 為Cl-或NCS-)。 利用實驗室傳統的萘燒法可成功地合成出六個不對稱異核金屬串錯合物，包括了(4,0)-[CuCuPd(npa)4Cl][PF6] (1) (npa- = naphthyridylphenylamido anion) 、(4,0)-[CuCuPd(npa)4(μ-NCS)Cu(NCS)2] (2) 、(4,0)-[CuCuPt(npa)4Cl][PF6] (3) 、(4,0)-[CuCuPt(npa)4(NCS)][PF6] (4)、(4,0)-[CuCuPd(ntfmpa)4Cl][PF6] (5) (ntfmpa- = naphthyridyl(4-trifluoromethylphenyl)amido anion) 和 (4,0)-[CuCuPd(nmpa)4Cl][PF6] (6) (nmpa- = naphthyridyl(4-methylphenyl)amido anion)。根據X-ray 單晶結構分析，六個錯合物的立體結構均為單一的(4,0)構型，配基上四個苯環基團皆朝向同一方向。此(4,0)構型的形成原因推測為配基上氮的配位能力差異，因為胺的氮傾向和鈀或鉑離子配位，而萘啶的氮則易和兩個銅離子配位。化合物末端的銅離子為有點扭曲的四方角錐五配位，而內部銅離子是微扭曲的四方平面配位。由於受配基上四個苯環基團的立體阻礙影響，鈀或鉑離子沒有額外的軸向配基，呈現四方平面配位結構。變溫磁化率量測結果顯示化合物兩個銅離子的未配對電子為強反鐵磁偶合，其磁交換偶合常數 (J) 分別為 -498.90 cm-1(1) 、 493.30 cm-1(2) 、 -501.24 cm-1(3) 、 -484.43 cm-1(4) 、 -520.77 cm-1(5) 和 -498.85 cm-1(6)。密度泛函數理論 計算的結果顯示銅上的未配對電子藉由空間傳遞而造成強反鐵磁偶合作用。此外，計算顯示鄰近異核金屬d 軌域之間具有高能量屏障，提示這類不對稱金屬串錯合物未來可應用在無機分子整流器方面的潛力。

A series of asymmetric heterometal string complexes, (4,0)[CuCuPd(npa)4Cl][PF6] (1) (npa- = naphthyridylphenylamido anion), (4,0)-[CuCuPd(npa)4(μ-NCS)Cu(NCS)2] (2), (4,0)[CuCuPt(npa)4Cl][PF6] (3), (4,0)[CuCuPt(npa)4(NCS)][PF6] (4), (4,0)[CuCuPd(ntfmpa)4Cl][PF6] (5) (ntfmpa- = naphthyridyl(4-trifluoromethyl phenyl)amido anion) and (4,0)[CuCuPd(nmpa)4Cl][PF6] (6) (nmpa- = naphthyridyl(4-methylphenyl)amido anion), have been synthesized and studied. According to the X-ray crystallography analysis, these complexes contain a linear CuCuM ( M = Pd or Pt ) framework which is supported by four asymmetric ligands. These asymmetric ligands adopt a (4,0) arrangement. All aniline N atoms coordinated to the M atom (M = Pd or Pt) and all naphthyridine N atoms coordinated to two Cu atoms. The coordination environment of the terminal copper of 1-6 is a distorted square pyramid. The coordination environment of the inner cooper is a distorted square planar. Because of the steric hindrance, the M atom is square planar coordinated without extra axial ligand. Temperature-dependent magnetic susceptibility of 1-6 revels that unpaired electrons of two Cu atoms are antiferromagnetically coupled (J ~ 500 cm-1), which is confirmed by DFT calculations. Interestingly, the large energy barrier between the d-orbitals of neighboring heterometals suggests that these complexes may exhibit potential application as future inorganic molecular rectifiers.