【作者】 张伟；

【导师】 赵艳霞；

【作者基本信息】 西北大学 ， 有机化学， 2018， 硕士

【摘要】 近年来,主族元素的化合物促进的单键断裂的化学反应得到了一定的发展,而多重键断裂的化学性质的研究仍未进一步的深入。本文以α-二亚胺的双核镓化合物[LGa-Ga L](1,L=dpp-dad=[(2,6-i Pr2C6H3)NC(CH3)]2)(1)与异硫氰酸酯为研究对象。化合物(1)与异硫氰酸酯按摩尔比为1:2的比例反应得到C=S双键环加成到C=C-N-Ga片段上的产物[L(RN=C-S)Ga-Ga(S-C=NR)L](2,R=Me;3,R=Ph),同时形成了新的C-C键和S-Ga键。化合物(1)与Ph NCS反应时Ga-Ga发生环加成和氧化断裂而C=S也发生了还原断裂的反应,并得到[L(Ph N=C-S)Ga(?-S)Ga(S-C=NPh)L](4)单个硫原子桥联的产物和[Na(THF)]2[L(Ph N=C-S)Ga(?-S)2Ga(S-C=NPh)L](6)两个硫原子桥联的产物。以及C=S键还原断裂两个硫原子桥联的而没有发生环加成反应的化合物[LGa(μ-S)2Ga L][Na(THF)3]2(5)。产物2-6通过NMR(1H,13C)、红外光谱、元素分析、X-单晶衍射分析、和电子结构的DFT量化计算。本文主要分成二部分第一部分,简略的介绍金属-金属键的发展历程,合成方法和晶体结构,以及化学反应性质等。第二部分,α-二亚胺Ga-Ga键化合物[LGa-Ga L](L=[(2,6-i Pr2C6H3)NC(Me)]2)(1)与异硫氰酸甲酯,异硫氰酸苯酯的活化反应。按不同的摩尔比反应时得到了一系列产物(2-6)。化合物(1)分别与异硫氰酸甲酯和异硫氰酸苯酯反应,得到了[2+4]环加成产物[L(Me N=C-S)Ga-Ga(S-C=NMe)L](2)和[L(Ph N=C-S)Ga-Ga(S-C=NPh)L](3),这两个产物中都存在[2.2.1]的环状结构。当化合物1与3.0当量Ph NCS反应得到化合物(4),化合物4的结构中除了含有N=C=S的部分与配体骨架的环加成结构之外,还有另一分子的异硫氰酸苯酯分子中C=S双键还原断裂,插入到Ga-Ga键之间形成硫原子桥联的结构。通过化合物1与2.0当量的Ph NCS在金属钠存在下反应得到化合物[LGa(μ-S)2Ga L][Na(THF)3]2(5),异硫氰酸苯酯只发生了插入反应却没有进行环加成的反应,化合物(5)中由两个硫原子桥联的四元环状的Ga2S2的结构。化合物1与4.0当量的异硫氰酸苯酯的反应,再进一步用2.0当量的金属钠还原,得到具有手性中心的两个硫原子桥联的二聚体化合物(6)。更多还原

【Abstract】 While the chemistry of single-bond cleavage promoted by main-group element compounds has gained some development in recent years,the cleavage of multiple bonds remains underexplored.Here we report the reactions of two digallanes with α-diimine ligands,[LGa-Ga L](1,L = dpp-dad = [(2,6-i Pr2C6H3)NC(CH3)]2)with isothiocyanates.The reaction of 1 with isothiocyanates in 1:2 molar ratio proceeded via [2+4] cycloaddition of C=S bond across the C=C-N-Ga fragment to afford [L(RN=C-S)Ga-Ga(S-C=NR)L](2,R = Me;3,R = Ph)with formation of the C-C and S-Ga single bonds.Interestingly,both cycloaddition and oxidative cleavage of Ga-Ga bond as well as reductive cleavage of the C=S bond occurred in the reaction of 1 with phenyl-isothiocyanate(Ph NCS),resulting in the mono-or di-S-bridged digallium complexes [L(Ph N=C-S)Ga(m-S)Ga(S-C=NPh)L](4)and [Na(THF)]2[L(Ph N=C-S)Ga(m-S)2Ga(S-C=NPh)L](6).The di-S-bridged digallium compounds [LGa(μ-S)2Ga L][Na(THF)3]2(5)were also obtained via cleavage of C=S double bond without cycloaddition.The products 2-6 have been characterized by NMR(1H,13C)and IR spectroscopy,elemental analysis,and X-ray diffraction,and their electronic structures were studied by DFT calculations.The first section,Simply introduce the history,synthesis methods and crystal structure of the typical metal-metal bond compound.In addition,synopically introduced the reaction properties of some metal-metal bond compounds.The second section,A Ga-Ga-bonded compound [LGa-Ga L](L = [(2,6-i Pr2C6H3)NC(Me)]2)(1),which is a example of Ga-Ga-bonded complex with α-diimine ligand,reacted with methyl-isothiocyanate(Me NCS)or phenyl-isothiocyanate(Ph NCS)in toluene afforded the [2+4] cycloaddition products [L(Me N=C-S)Ga-Ga(S-C=NMe)L](2)and [L(Ph N=C-S)Ga-Ga(S-C=NPh)L](3)with the [2.2.1] bicycle.When the amount of Ph NCS was increased to 3.0 equivalents,the reaction with 1 led to a different dinuclear product [L(Ph N=C-S)Ga-S-Ga(S-C=NPh)L](4).Besides cycloaddition of two N=C=S moieties to the metal-ligand backbones as in 2 and 3,a unique reductive C=S bond cleavage occurred to the third Ph NCS molecule with accompanying breaking of the Ga-Ga bond,yielding the digallium species 4 bridged by a sulfur atom.The di-S-bridged digallium compound [LGa(μ-S)2Ga L][Na(THF)3]2(5)with a four-membered Ga2S2 central core was obtained in good yield by the reaction of digallane 1 with 2.0 equiv of Ph NCS in the presence of Na metal.In this case no cycloaddition of the isothiocyanate occurred but only cleavage of C=S was observed to generate the bridging sulfur ligands.The reaction of precursor 1 with even more(4.0 equiv.)phenyl isothiocyanate followed by treatment with 2 equiv.of Na proceeded smoothly,affording the unique centrosymmetric dimer 6 that is bridged by two sulfur atoms resulted from the C=S bond cleavage.更多还原