Hydrogen bond, bifurcated

The study of Rozas et al. relies on the HB criteria proposed by Koch and Popelier21 and proves the existence of bifurcated bond paths and distinguishes four different types of interactions based on the degree of symmetry and magnitude of the two pb values. Therefore, looking at the geometry, electron density, and energy results, the nature of these HBs as three-centred interactions has been confirmed. 

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Coll, M., C. A. Erederick, A. H. J. Wang, and A. Rich. A bifurcated hydrogen-bonded conformation in the D(A-T) base-pairs of the DNA dodecamer D(CGCAAATTTGCG) and its complex with distamycin. Proc. Natl. Acad. Sci. USA 1987, 84, 8385-8389. 

The complexes formed by H5 bound to 01 were found to be slightly less stable than the new with H5 bound to 02, for both the guanidinium and the pyrolidinium complex. Both type of complexes feature bifurcated hydrogen bonds, with 02 bound to H5 and H6. The double binding is achieved with some cost to the linearity of the hydrogen bond. The most stable complexes have been found to be planar. 

From the first transition state (TSl, Fig. 1), the reaction path leads to the tetrahedral intermediate 1 (INTI). In the latter, the proton transfer from methanol to the tertiary amine function is completed (from 1.183 to 1.059 A), and the negative charge at the former carbonyl oxygen atom reaches its maximum. This charge is compensated by a further shortening of the bifurcated hydrogen bonds to 2.040 A (-0.103 A) and 1.765 A (-0.096 A) (Fig. 1). The thiourea moiety thus forms an oxyanion hole similar to the amide groups of the serine protease backbone [41]. 

The largest number of hydrogen bonds in crystal structures of alkyl hydroperoxides refer to intermolecular bonds between the hydroperoxide proton and functionalities of the type 0=X, where X denotes a sulfur (e.g. 27), carbon (e.g. 30) or a phosphorous atom (e.g. 32, Figure 14, Table 7)93,108,115 geometry of [l,2-bis(diphenylphosphinoyl)ethane] bis(2,2-dihydroperoxypropane) (32) in the solid state is a rare example of a bifurcated hydrogen bond between an OOH donor and an 0=X proton acceptor. 

Bifurcated hydrogen bonds, alkyl hydroperoxides. 111, 112 Bimetalbc complexes, molybdenum(Vl), 428 Bioassays... 

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