Reactions of a BICAAC with hydroboranes: propensity for Lewis adduct formation and carbene insertion into the B-H bond

Krishna K Manar; Vishal Kumar Porwal; Rohit S Kamte; Manu Adhikari; Sandeep Kumar Thakur; Deependra Bawari; Angshuman Roy Choudhury; Sanjay Singh

doi:10.1039/c9dt03382c

Reactions of a BICAAC with hydroboranes: propensity for Lewis adduct formation and carbene insertion into the B-H bond

Dalton Trans. 2019 Dec 3;48(47):17472-17478. doi: 10.1039/c9dt03382c.

Authors

Krishna K Manar¹, Vishal Kumar Porwal, Rohit S Kamte, Manu Adhikari, Sandeep Kumar Thakur, Deependra Bawari, Angshuman Roy Choudhury, Sanjay Singh

Affiliation

¹ Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali 140306, Punjab, India. sanjaysingh@iisermohali.ac.in.

PMID: 31714564
DOI: 10.1039/c9dt03382c

Abstract

The reactivity of a bicyclic (alkyl)(amino)carbene (BICAAC) towards different boranes has been examined in the present work. The reactions with boranes BX3·SMe2 (X = H, Cl, Br), BF3·OEt2 and BCl3 yield Lewis adducts [BICAAC·BH3] (1), [BICAAC·BHCl2] (2), [BICAAC·BH2Cl] (3), [BICAAC·BF3] (4), [BICAAC·BCl3] (5) and [BICAAC·BBr3] (6) respectively, whereas more hydridic boranes, 9-borabicyclo[3.3.1]nonane (9-BBN) and catecholborane (HBcat), enable the insertion of the carbene carbon into the B-H bond to form [BICAAC(H)-(9-BBN)] (7) and [BICAAC(H)-Bcat] (8). These complexes are the first examples of BICAAC-boron compounds and have been characterized using IR, multinuclear NMR spectroscopy, HRMS spectrometry and single crystal X-ray diffraction. Computational analyses were also performed to gain insight into the mechanism of B-H bond activation and adduct formation. Furthermore, the reactions of the BICAAC with boranes have been compared with the known reactions of CAACs and NHCs.