Heteroborane analogs of silicon clusters: Experimental and theoretical studies on Bi2Si5 and Bi2Si5−

Abstract

We have investigated the electronic structure of anionic and neutral Bi(2)Si(5) by means of anion photoelectron spectroscopy and density functional calculations. Both the experiments and calculations reveal that the Bi(2)Si(5)(-) anion prefers to adopt a distorted trigonal-bipyramidal structure with Bi(2) bridges. Following the isolobal analogy between divalent Si and B-H group, we show that both neutral Bi(2)Si(5) and neutral Bi(2)B(5)H(5) adopt similar pentagonal-bipyrmidal geometries and have analogous orbital energy patterns.

Structural reciprocity effect in binary silicon–bismuth clusters

“…Through this analogy it was illustrated that the structures of Bi 2 Si nÀ2 clusters are obtained from the structure of the corresponding Si n 2À dianions by simple Bi ? Si substitution [19,20]. It was verified [19,20] for instance, that Bi 2 Si 5 has the same pentagonal dipyramidal structure as Si 7 2À , and Si 5 C 2 H 2 which are similar and isolobal [20] to (BH) 7 2À , (BH) 5 C 2 H 2, and (BH) 5 Bi 2 .…”

“…Si substitution [19,20]. It was verified [19,20] for instance, that Bi 2 Si 5 has the same pentagonal dipyramidal structure as Si 7 2À , and Si 5 C 2 H 2 which are similar and isolobal [20] to (BH) 7 2À , (BH) 5 C 2 H 2, and (BH) 5 Bi 2 . For Bi 2 Si 4 however, it was found [20] that in addition to the low energy structures obtained from Si 6 2À dianion, there were even lower energy structures (and among them the lowest) related to the Si 6 neutral cluster rather than the Si 6 2À dianion.…”

“…Dibismuthic clusters of the form Bi 2 Sn 10 have been also studied by the present author [20] in the context of the 'boron connection' isolobal analogy [20][21][22][23]. This analogy allows the structural and electronic correlation between [19][20][21][22][23] Si n 2À , (B n H n ) 2À dianions, C 2 B nÀ2 H n,…”

“…Yet, there have been only few studies on binary Bi-Si (or Bi-Ge, or Bi-Sn) clusters, until recently [15,[19][20][21]. Recently, Sun et al [15] have examined experimentally and theoretically neutral and anionic clusters of the form Bi n Si m 0, À1 (and similarly for Bi-Ge and Bi-Sn clusters) with n + m 6 6; while more recently Li et al [19] and Zdetsis [20] have studied dibismuthic clusters of the form Bi 2 Si 5 and Bi 2 Si nÀ2 (with n = 3-12) respectively. Dibismuthic clusters of the form Bi 2 Sn 10 have been also studied by the present author [20] in the context of the 'boron connection' isolobal analogy [20][21][22][23].…”

“…2Bi isoelectronic substitution involving 5 valence electrons. The same substitution is behind the schematical formation of bisboranes from boranes or carboranes [19][20][21]. The advantage of invoking such isoelectronic and isolobal analogies is the exploitation of the well known and well tested powerful structural and stability principles, as well as electron counting rules developed for boranes and carboranes [24][25][26][27], in the study of such (seemingly very different) molecular systems.…”