Silicon compounds, 120; Supersilyl compounds of boron and homologues, 6. Part 119 - Tetrasupersilyldialuminum [(t-bu)(3)Si](2)Al-Al[Si(t-Bu)(3)](2): The dialane(4) with the longest Al-Al bond to Date

Reaction of AlX3 (X = Cl, Br) with R*Na (R* = supersilyl, Si(t-Bu)(3)) in h eptane at room temperature gave the ruby dialane R*Al-2-AlR*(2) (1). X-ray structure analysis showed it to contain a Si2Al-AlSi2 skeleton with D(2)d s ymmetry and the longest Al-Al bond to date (2.751(2) Angstrom). Water- and air-sensitive 1 reacts with iodine or hydrogen to form R*2AlI or R*2AlH, re spectively. Thermolysis and photolysis transform 1, via [R*Al-2-AlR*](.), i nto the tetraalatetrahedrane Al4R*(4).