Multidentate interaction

Protonated and diprotonated carbonic acid and carbon dioxide may also have implications in biological carboxylation processes. Although behavior in highly acidic solvent systems cannot be extrapolated to in vivo conditions, related multidentate interactions at enzymatic sites are possible. 

Elimination of the multidentate interaction of a counterion with the siloxane chain is crucial. Otherwise, as mentioned before, the equilibration reactions would make the precision polymerization impossible. Specific initiator-solvent systems used for this purpose may be divided into three groups (1) basic solvent and a hard counterion, which interacts with solvent stronger than with siloxane, for example, lithium/THF (2) bulky and soft counterions, for example, Me4N BtuP, and phosphazenium cations, which weakly interact with nucleophiles (3) basic promoters strongly interacting with counterions, such as HMPT, DMSO, DMF, cryptands, and crown ethers. ... 

Charge-charge repulsion effects in protolytically activating charged electrophiles certainly play a significant role, which must be overcome. Despite these effeets multidentate protolytic interactions with superacids can take plaee, increasing the electrophilie nature of varied reagents. 

Dendrimers can be constructed from chemical species other than purely organic monomers. For example, they can be built up from metal branching centres such as ruthenium or osmium with multidentate ligands. The resulting molecules are known as metallodendrimers. Such molecules can retain their structure by a variety of mechanisms, including complexation, hydrogen bonding and ionic interactions. 

Bi-0 2.54(l)-2.68(2) A], In contrast, the nine-coordinate capped square antiprism geometry for bismuth in [Bi(N03)3(H20)3] (18-crown-6) does not involve the expected multidentate ether coordination to bismuth, but rather a hydrogen-bonded interaction of the crown ether with the hydrated bismuth center chelated by bidentate nitrate groups [Bi-0 2.38(2)—2.56(2) A] 32, implying that the hexado-... 

For interactions of cations with multidentate ligands, the corresponding zIGl has to include, besides contributions a)—e) the free energy changes associated with the following ... 

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