Beryllium dialkoxides

Beryllium dialkoxides are generally insoluble nonvolatile compounds, but the use of bulky alkoxo groups imparts solubility and volatility. Thus the fert-butoxide is trimeric" and the triethylcarbinol derivative [Be(OCEt3)2] is dimeric, but to date no crystal structure has been reported. 

In all of, these cases substitution of the second alkyl can then occur to yield the dialkoxide or diphenoxide. This allowed the isolation of the monomeric beryllium phenoxide Be(OAr )2 (OAr = 2,6-di-t-butylphenoxide).98 The alkyls of the Group IV metals, MR (M = Ti, Zr, Hf), undergo rapid reactions with common alcohols and phenols yielding eventually the corresponding tetra-alkoxides or -phenoxides and four equivalents of alkane.97,100 With very bulky substituted alcohols or phenols the reactivity can be very sluggish, in some cases leading to only partial substitution (equation 28). 66,100... 

Similar to beryllium n-diaUcoxides, zinc dialkoxides are also insoluble and nonvolatile compounds. " " The alkylzinc alkoxides are, however, less polymeric and exhibit higher volatility. For example, the cryoscopic molecular weight determination in benzene indicates that methylzinc methoxide and terf-butoxide as well as ethylzinc tert-butoxide are tetrameric" with sublimation temperatures of 60, 95, and 105°C, respectively under 0.0001 mm pressure. ... 

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