Diborane(4) has been produced by abstraction of two hydrogen atoms from diborane(6) using atomic fluorine and detected by photoionization mass spectrometry.[1] Computational studies predict a structure in which are two hydrogen atoms bridging the two boron atoms via three-centre two-electron bonds in addition to the 2-centre, 2-electron bond between the two boron atoms and one terminal hydrogen atom bonded to each boron atom.[2]
Several stable derivatives of diborane(4) have been reported.[3][4][5]
^Ruščic, B.; Schwarz, M.; Berkowitz, J. (1989). "Molecular structure and thermal stability of B 2H 4 and B 2H+ 4 species". The Journal of Chemical Physics. 91 (8). AIP Publishing: 4576–4581. doi:10.1063/1.456745.
^Xie, Xiaochen; Haddow, Mairi F.; Mansell, Stephen M.; Norman, Nicholas C.; Russell, Christopher A. (2012). "Diborane(4) compounds with bidentate diamino groups". Dalton Transactions. 41 (7): 2140–7. doi:10.1039/C2DT11936F. PMID22187045.
^Wagner, Arne; Kaifer, Elisabeth; Himmel, Hans-Jörg (2012). "Diborane(4)–metal bonding: Between hydrogen bridges and frustrated oxidative addition". Chemical Communications. 48 (43): 5277–9. doi:10.1039/C2CC31671D. PMID22526934.
^Horn, Julian; Widera, Anna; Litters, Sebastian; Kaifer, Elisabeth; Himmel, Hans-Jörg (2018). "The proton affinity, HOMO energy and ionization energy of electron-rich sp3–sp3-hybridized diborane(4) compounds with bridging guanidinate substituents can be varied by substitution". Dalton Trans. 47 (6): 2009–2017. doi:10.1039/C7DT04433J. PMID29345706.