The synthesis of hypervalent tris(catecho1ato)silicate ion, f(C6H402)3Si12~~ with six different counter cations: (i) diethylammonium (I), (ii) triethylammonium (II), (iii) diisopropylammonium (III), (iv) morpholinium (IV), (v) piperazinium (V) and (vi) N-methylpiperazinium (VI) has been achieved (yield: ~~7.95%) by the reaction of catechol and tetraethoxysilane in presence of the corresponding amine. Single crystal X-ray structure of compound ( 111) has been determined. It crystallizes in orthorhombic system [space group P2,2121; n = 11.735(2), b = 13.708(3), c = 23.283(5) A; 01 = 90", ,!!= 90"' -y = 90"; Volume = 3745.4(11) A3; Density = 1.165 gcni-3; Z = 4; X = 0.0585; wR2(I) = 0.1610 and 3677 reflections] and the structure shows slightly distorted octahedral geometry around silicon. Results of TG, DT and EG analysis of compounds (I) -(VI) reveal the influence of the counter cation on thermal stability. Bench scale pyrolysis of (I) and (11) convert them to [(ChH402)2Si],I by the quantitative expulsion of ammonium catecholate salt, (M')2[(ChH402)12-. CP-MAS 29Si-nmr spectral data suggests that [(ChH402)2Si]iI is a simple mixture.

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