Hydrogen bonding chains

Fig. 3. The hydrogen-bonded chain structure of (2-morpholinoethyDdiphenylsilanol with the hydrogen atoms omitted for clarity. Drawn using coordinates taken from the Cambridge Crystallographic Database. 

The anhydrous silanol ButMe2SiOH is a liquid, but on exposure to moisture it forms a solid hemihydrate [ButMe2Si0H]2.H20 (52,241) in which hydrogen-bonded chains are formed with the water molecules acting as linkages down the chain (Fig. 7). The carbon analogue... 

The simple diols R2Si(OH)2 (R = Pr , Bul, c-C6Hn, and o-tolyl) form similar, but not identical, hydrogen-bonded chains. The structures of the Pr1 (305), Bu (40, 278), and c-C6Hn (292) compounds are very similar in that they comprise ladder chains of the general type 65, in which pairs of molecules are linked to form dimers and then further hydrogen bonds link the dimers to form the chains. [It has also been... 

Pomes, R. Roux, B., Free energy profiles for H+ conduction along hydrogen-bonded chains of water molecules, Biophys. J. 1998, 75, 33-40... 

There is also the possibility of Davydov coupling, which is likely to appear when there are double or multiple H-bond systems [7,21-23]. It is responsible for cooperative effects between neighboring hydrogen bonds in cyclic hydrogen bonded dimers, or more generally in hydrogen-bonded chains in solids [ 10,24—34]. 

The observed range of the shear modulus varies between 1.5 GPa in filaments of regular count to 3 GPa in microfilaments, which correlates with the degree of orientation and crystalline perfection in the fibres [40]. Compared to the theoretical value of the modulus of shear between two hydrogen-bonded chains of 4.1 GPa, it indicates softening due to the van der Waals bonding between the hydrogen-bonded planes. 

For chain-like or cyclic hydrogen bond patterns between three alcohol molecules A, B, and C, Vabc is usually negative (attractive). If molecule B acts as an acceptor for both A and C, Vabc is typically repulsive (positive), because A and C compete for the electron density at B [61]. This anti-cooperativity provides the main explanation why branching of hydrogen-bonded chains is discouraged in alcohols. 

Most network structures involving crown ethers are simple hydrogen bonded chains where the crown forms second sphere coordination interactions with a complex ion. These are known for [18]crown-6, [15]crown-5 and [12]crown-4 hosts with a variety of metal complexes [17-25]. For instance when combined with the small [12] crown-4, the perchlorate salts of Mn(II), Ni(II) and Zn(II) form polymeric chain structures with alternating crown ethers and [M(H20)6]2+ cations [19]. Similarly the larger [18]crown-6 forms simple linear chains with metal complexes and cations such as fra s-[Pt(NH3)2Cl2] [20], [Cu(NH3)4(H20)]2+ (Fig.2) [21],and [Mg(H20)5(N03)] + [22],... 

Fig. 2 Linear hydrogen bonded chain structure formed between [18]crown-6 and [Cu(NH3)4 (H20)P [21]...

Fig. 3 Helical hydrogen bonded chain structure formed between [15]crown-5 and [La(N03)3 (H2O)2(l,10-phenanthroline)].[24]... 

Fig. 4 The pseudorotaxane 10 of dibenzo[24]crown-8 and para-carboxylic acid substituted dibenzylammonium, linked to form a hydrogen bonded chain. Only hydrogen atoms involved in hydrogen bonding are shown [31]...

A ferris wheel assembly involving a 1 1 complex of 19 and metallated [18]crown-6 is found in the cationic supermolecule [La(H20)3([ 18]crown-6)] (19+2H) + [48]. The lanthanum ion is coordinated by one calixarene sulfonate group, the [18] crown-6 and three aquo ligands, and the metallated crown sits inside the calixarene cavity. A helical hydrogen bonded chain structure is formed between the cationic assembly, water and chloride ions. The ferris wheel structural motif is also found in Ce3+ complex which simultaneously contains a Russian Doll assembly [44]. 

Fig. 11 Linear 1D hydrogen bonded chain structure of (C-methylcalix[4]resorcinarene).2 (4,4 -bipyridine)(4-bromobiphenyl) [57]... 

Fig. 25 The hydrogen bonded chain structure in complex [ Mo3S4(H20)7Cl2 2Hg](5)Cl4.14H20 where [ Mo3S4(H20)7Cl2 2Hg]4+ clusters are sandwiched between host 5 molecules [102]... 

Fig. 26 The zig-zag hydrogen bonded chain of [W3S4(H2O)7Cl2](5) Cl2.10H2O B8 [103]...

In the calculations of the energy of hydration of metal complexes in the inner coordination sphere, one must consider hydrogen bond formation between the first-shell water molecules and those in bulk water, which leads to chains of hydrogen-bonded water molecules. Such hydrogen-bonded chains of ethanol molecules attached to the central metal ion have been found as a result of DFT B3LYP calculations on ethanol adducts to nickel acetylacetonate, where the calculated energy of hydrogen bonds correlated well with experimental data [90]. 

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