Substances Containing Bridging Methyl Groups

Pt4(CHa)i . The small circles represent platinum atoms and the large circles carbon atoms of the methyl groups. 

The increase in ligancy of the carbon atom illustrates the principle, mentioned in Section 10-6, that an electron-deficient atom causes adjacent atoms to increase their ligancy. The platinum atom in the monomer, Pt(CHf)4, would make use of only seven of its nine valence orbitals four for bonds to the four carbon atoms and three for the three unshared pairs of bd electrons. The electron deficiency of this atom then permits the increase in ligancy of carbon. 

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