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

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.