Dicarba‐closo‐dodecaboranes with One and Two Ethynyl Groups Bonded to Boron

Abstract

The diethynyldicarba‐closo‐dodecaboranes 1,2‐R2‐9,12‐(HCC)2‐closo‐1,2‐C2B10H8 [R = H (1a), Me (2a)] and 9,10‐(HCC)2‐closo‐1,7‐C2B10H10 (3a) were obtained by Pd‐catalyzed Kumada‐type cross‐coupling reactions of the corresponding diiodinated dicarba‐closo‐dodecaboranes withMe3SiCCMgBr followed by desilylation of the trimethylsilylalkynyl‐substituted clusters. In addition, the related {closo‐C2B10} derivatives with one ethynyl group 1,2‐R‐9‐HCC‐closo‐1,2‐C2B10H9 [R = H (4a), Me (5a)], 9‐HCC‐closo‐1,7‐C2B10H11 (6a), and 2‐HCC‐closo‐1,12‐C2B10H11 (7a) were synthesized and their spectroscopic properties were compared to those of the diethynyl‐substituted {closo‐C2B10} clusters. The ethynyl‐ and trimethylsilylalkynyl‐functionalized dicarba‐closo‐dodecaboranes were characterized by elemental analysis, mass spectrometry, as well as by multinuclear NMR, IR, and Raman spectroscopy. The assignment of the NMR spectroscopic chemical shifts and the IR and Raman bands is supported by theoretical values derived from density functional calculations. The crystal structures of 9,12‐(HCC)2‐closo‐1,2‐C2B10H10 (1a), 9,10‐(HCC)2‐closo‐1,7‐C2B10H10 (3a), and 1,2‐Me‐9,12‐(Me3SiCC)2‐closo‐1,2‐C2B10H8 (2b) were determined by single‐crystal X‐ray diffraction. Selected experimental bond properties are compared to bond lengths and angles calculated at the B3LYP/6‐311++G(d,p) level of theory.

Boron Clusters with a Ferrocenylalkynyl Group Bonded to Boron: Synthesis, Characterization, and Electrochemical Trends

“…Cesium carba‐ closo ‐dodecaborate was synthesized from [Me 3 NH][ nido ‐B 11 H 14 ]32 and [ n Bu 4 N] 2 [ closo ‐B 12 H 12 ] was synthesized from [Me 3 NH][ nido ‐B 11 H 14 ] and BH 3 · NEt 3 33. The monoiodinated clusters 9‐I‐ closo ‐1, 2‐C 2 B 10 H 11 ,34 9‐I‐ closo ‐1, 7‐C 2 B 10 H 11 ,12a Cs[12‐I‐ closo ‐1‐CB 11 H 11 ],16a,23 Cs[1‐H 2 N‐12‐I‐ closo ‐1‐CB 11 H 10 ],11b and [ n Bu 4 N] 2 [I‐ closo ‐B 12 H 11 ]35 were synthesized from the non‐iodinated derivatives following known protocols.…”

Photoluminescence in Carborane–Stilbene Triads: A Structural, Spectroscopic, and Computational Study

“…In the 11 B{ 1 H} NMR spectra of m ‐carborane derivatives 3 – 8 , the most asymmetric mono‐iodinated compounds 5 and 6 show 2:1:1:2:1:1:1:1 patterns, whereas non‐iodinated 3 and 4 and diiodinated 7 and 8 show more symmetrical distributions of the boron resonances with 2:6:2 and 2:4:2:2 patterns, respectively. Moreover, for all iodinated derivatives 5 – 8 the BI groups were indubitably identified as having the highest‐field resonances in the range from δ =−21.14 to −26.37 ppm, which remain as singlets in the 11 B NMR spectra . No significant differences in the 11 B{ 1 H} NMR resonances between corresponding carborane derivatives substituted with styrene or stilbene fragments were found.…”

Cesium and Tetrabutylammonium Salt of the Ethynyl‐closo‐dodecaborate Dianion

“…The isoelectronic boron clusters [HC≡C‐ closo ‐B 12 H 11 ] 2– ( 1 ), [12‐HC≡C‐ closo ‐1‐CB 11 H 11 ] – 13 and 9‐HC≡C‐ closo ‐1, 2‐C 2 B 10 H 11 ,14 which all exhibit an ethynyl group that is bonded to a cluster boron atom, differ in the number of carbon and boron atoms in the 12‐vertex cluster and hence, in the charge of the cluster. In Table 3 selected experimental and calculated structural and spectroscopic properties are compared.…”