Synthesis and X-ray crystal structure of [(THF)Zn(O2(OH)SiR)]4 (R = (2,6-i-Pr2C6H3)N(SiMe3)):: Enroute to larger aggregates

Reaction of aminosilanetriol RSi(OH)(3) (1) (R = (2,6-i-Pr2C6H3)N(SiMe3)) with diethyl zinc at room temperature in 1:1 stoichiometric ratio affords [(THF)Zn(O-2(OH)SiR)](4) (2) (R = (2,6-i-Pr2C6H3)N(SiMe3)) in good yield. The single-crystal X-ray diffraction studies reveal that 2 is monoclinic, P2(1), with a = 17.117(3) Angstrom, b = 16.692(5) Angstrom, c = 17.399(4) Angstrom, alpha = gamma = 90degrees, beta = 91.45(7)degrees, and Z = 2. The molecular structure of 2 contains two puckered eight-membered Zn2Si2O4 rings, which are connected by the Zn-O bonds and form two planar four-membered Zn2O2 rings. Compound 2 contains an unreacted hydroxyl group on each silicon atom, and hence, we carried out the reactions of 2 with dimethylzinc and methyllithium to form [Zn-4(THF)(4)(MeZn)(4)(O3SiR)(4)] (3) (R = (2,6-i-Pr2C6H3)N-(SiMe3)) and [(L)ZnLi(O3SiR)](4) (4) (L = 1,4-(Me2N)(2)C6H4, R = (2,6-i-Pr2C6H3)N(SiMe3)), respectively. This suggested that 2 could be an intermediate product formed during the synthesis of 3 and 4.