Octet rule electron pair acceptors

Since an interaction between two molecules generally involves charge transfer, it may be considered as a donor-acceptor interaction in the widest sense of the word The formation of coordination donor-acceptor bonds between acceptors with low-lying vacant AOs and donors with accessible electron pairs is typical of the majority of elemnts of the periodic system, e.g., the silicon atom can form more bonds than appears to be allowed by the octet rule An eminent problem... 

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