铌硫簇离子的激光产生与质谱分析

MASS SPECTROMETRY OF NIOBIUM AND SULFUR MIXED CLUSTER IONS GENERATED IN LASER PLASMA

黄建全、卢嘉锡等提出的[MO3S4]4+簇骼中Mo3S3簇环具有类芳香性本质的观点,已逐渐为国内外化学者所接受。围绕着这一思想,我们最近在自制的仪器上进行了铌与硫的激光等离子体反应。在高温的激光等离子体中,各种物种一般皆有较高的内能,所以只有结构很稳定的化合物离子才可能较大量地生存下来,为质谱计所检测。铌仅比钼少一个价电子,Nb3S44+与[MO3S4]4+是等电子的,铌与钼为同一周期的相邻元素,所以Nb3S4+很可能也同样具有类芳香性的Nb3S3簇环,结构比较稳定。如果是这样的话,它应当在激光等离子体质谱中有突出的信号强度。我们的实验结果正是如此。

Cluster ions of niobium and sulfur were generated in laser plasma reactions on aself-built apparatus. Among all Nb_nS_m^+, the cluster cations with the compositions ofn<4, m=n+1; n>3, m=n+2 have special high ion intensities in mass spectrum.The cluster anions of high intensities have four more sulfur atoms compared with therelative cations. By analogousing to [Mo_3S_4]^(4+) clusters, it is proposed that thesecluster ions contain non-planar puckered rings with quasi-aromaticity.