Water- and oxygen-sensitive compounds R*EHal2•D, R*EHal2 and R*2EHal (R* = SitBu3; E = B, Al, Ga, In, TI; Hal = F, Cl, Br, I; D = OR2, NR3) have been synthesized by reaction of EHal3 with NaR* in the absence or presence of donors as well as by substitution of D, Hal or R* by other substituents, or by reaction of R*2E-ER*2 (E = Al, In) with I2, H2, AgF2 or HBr. Thermal decomposition of the compounds in solution or in the gas phase leads to elimination of D from R*EHal2•D, or of R*Hal from R*EHal2 and R*2EHal, respectively. The dihalides R*EHal2 act as Lewis acids with respect to donors OR2 or NR3 (formation of adducts R*EHal2•D), the monohalides R*2EHal as Lewis bases with respect to acceptors EHal3 (formation of R*2E+ EHal4 -). Dehalogenations of R*2EHal and R*EHal2 with alkali metals or NaR* leads to compounds R*4E2 (E = AI, In, Tl), R*3E2• (E = AI, Ga), R*4E3 • (E = Al, Ga), R*4E4 (E = AI, Ga), R*6Ga8, R*8In12, (R*2B- ), R*2A- , R*3Ga2 -, R*4Ga3 -, R*4Ga4 2-, R*4Tl3Cl, or R*6Tl6Cl2. The structures of R*BBr2•Py, R*AlBr2•NEtMe2, (R*AlClOBu)2, R*2BF as well as R*2ECl (E = B, Al, Ga, Tl) have been determined by X-ray structure analyses.