Rearrangement of Bis(dimethylamino)bis(1-indenyl)diborane(4) into Bis(dimethylamino)bis(3-indenyl)diborane(4)

Abstract

Indenyllithium reacts with dichlorobis(dimethylamino)diborane(4) with formation of bis(dimethylamino)bis(1‐indenyl)diborane(4) which rearranges on heating to the isomer bis(dimethylamino)bis(3‐indenyl)diborane(4). The „mixed” bis(dimethylamino)(1‐indenyl)(3‐indenyl)diborane(4) is obtained from indenyllithium and chlorobis(dimethylamino)(3‐indenyl)diborane(4). The main structural differences between the two isomers 3 and 4 are a slightly shorter B−B bond in 4, as well as a stronger twist about the B−B bond (89.9° vs. 67.4°) and, as expected, a shorter B−C bond. There is, however, no significant B−C π bonding.

Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse

“…In an attempt to enhance the applicability of these compounds, a number of second-generation diboron(4) compounds, based on tetrakis­(dimethylamino)­diboron(4), have been prepared and studied. Although a few mixed amino and halide compounds have been synthesized, ,, a significant amount of research has focused on generating organoborane(4) derivatives containing B–C bonds. ,− Of synthetic interest is a report by Wakamiya, Yamaguchi et al, who prepared and studied the boracycle dithieno-1,2-dihydro-1,2-diborin and its dianion as potential building blocks for extended π–electron systems for making optoelectronic materials (Scheme ). The same group went on to synthesize two other diarene-fused diborin dianions and investigate the structural features and photophysical properties of these compounds …”