Reported is the first rational synthesis of a trisubstituted deltahedral Zintl ion, [Ge-9{Si(SiMe3)(3)}(3)](-) in this case, by the addition of the three substituents in a reaction of the parent naked deltahedral Zintl ion Ge-9(4-) with {(Me3Si)(3)Si}Cl. The new species were crystallized and structurally characterized in [K(2,2,2-crypt)](2)[Ge-9{Si(SiMe3)(3)}(3)] (monoclinic, P2(1)/c, a = 26.497(3) angstrom, b = 24.090(2) angstrom, c = 29.268(3) angstrom, beta = 113.888(2)degrees, V = 17082(3) angstrom(3), Z = 8, R1/wR2 = 0.0436/0.0812 for the observed data and 0.1023/0.1010 for all data).