Direct Phenylation of nido-B₁₀H₁₄

Abstract

As a preliminary step toward its condensation into the porous polymer Activated Borane, the thermolysis of nido-B10H14 (1) in benzene at 200 °C results in the generation of a number of phenylated borane molecular species. The principal product is the new monophenylated compound 5-Ph-nido-B10H13 (2), isolated in 48% yield (based on consumption of 1) and structurally characterized by single-crystal X-ray diffraction analysis, NMR, and mass spectrometry along with other minor products, such as 6-Ph-nido-B10H13 (3), for which we observe UV-light-driven conversion into 2 via a “vertex-flip” mechanism, and novel diphenylated 5,8-Ph2-nido-B10H12 (4). Together, the phenylated derivatives provide a valuable insight into the assembly of Activated Borane and ultimately inform on its structure. The new compounds also display strong blue fluorescence in both solid-state and in solution and are the first examples of the direct phenylation of nido-B10H14, thus opening the door to the straight-forward synthesis of highly luminescent organic-borane hybrid systems.

“Activated Borane”: A Porous Borane Cluster Polymer as an Efficient Lewis Acid-Based Catalyst

“…It has been observed earlier (e.g., see the work of J. Kennedy) that open borane clusters subject to high energy (e.g., thermolysis, photolysis, and electron bombardment) form clusters with different number of vertices. We made similar observations during the thermal treatment of nido -B 10 H 14 in benzene at 200 °C where we detected substituted B 18 H 22 clusters . This change in the number of boron vertices is probably accompanied by the formation of highly reactive lower boranes that are the seeds for LA centers.…”

“…We made similar observations during the thermal treatment of nido-B 10 H 14 in benzene at 200 °C where we detected substituted B 18 H 22 clusters. 17 This change in the number of boron vertices is probably accompanied by the formation of highly reactive lower boranes that are the seeds for LA centers.…”

“…ActB is a porous polymer that is formed by cothermolysis of decaborane(14) ( nido -B 10 H 14 ) and organic solvents such as toluene or hexane. We have shown that the structure of ActB is most probably composed of closo borane clusters linked together by organic linking moieties …”

“…We have shown that the structure of ActB is most probably composed of closo borane clusters linked together by organic linking moieties. 17 Here, in this paper, we present an improved strategy for the synthesis of ActB and present evidence for the catalytic activity of its Lewis acidic boron sites as well as a comparison of its performance compared with contemporary catalysts. The nature of the Lewis acid sites in ActB was characterized by the Gutmann−Beckett method ( 31 P solid-state NMR after the adsorption of Et 3 PO) and by temperature-programmed desorption of ammonia.…”

“Activated Borane” – A Porous Borane Cluster Network as an Effective Adsorbent for Removing Organic Pollutants

“…[25] In a further effort to understand the structural aspects of ActB, we embarked on a study of a lower temperature thermolysis (200 °C for 36 h) of nido-B 10 H 14 in benzene in the hope to isolate intermediate molecular species that arise prior to eventual condensation into the reported porous polymeric form. In this separate study, [26] we have isolated and characterized monophenyldecaborane (c.a. 30 % yield of all isomers) and diphenyldecaborane (< 5% yield of all isomers) species, and obtained evidence for tri-phenylation and the fusion of decaborane clusters to form B 18 H 22 .…”