For traditional sandwichlike molecular materials, the spin properties are not governed by the closed-shell sandwich decks, but by the type of center atoms and by the interaction between the center atom and the deck. Here, on the basis of density functional theory calculations, we report a kind of 1D, 2D, and 3D cluster-assembled sandwichlike molecular materials [D(CAl3Si)M](q+), saturated compounds (Cl-)(q)[D(CAl3(Si)M](q+) (D = CAl3Si, Cp-(C5H5-); M = Li, Na, K, Be, Mg, Ca) as well as the extended frameworks, whose spins are purely determined by the planar tetracoordinated carbon (ptC) radical-deck (CAl3Si). To capture and stabilize the ptC radical, we proposed a scheme "heterodecked sandwich", in which way CAl3Si can act as a spin-embedded "superatom" because of the well conservation of the radical's spin, structural and electronic integrity during the cluster assembly. This should represent the first attempt to assemble a spin-deck into the magnetic molecular materials, which provides a bridge between the planar carbon chemistry and the spintronics realm.