Multicentred hydrogen bonds

Thakur, T. S., Desiraju, G. R., Misassigned C-HCu agostic interaction in a copper(II) ephedrine derivative is actually a weak, multicentred hydrogen bond. Chem. Commun. 2006, 552-554. 

Figure 2 Multicentred hydrogen bond arrangements (a) bifurcated and trifurcated donors and (b) bifurcated acceptor (see Jeffrey and Saenger [27])...

In B2H6, two BH2 groups are linked by bridging hydrogens in two B—H—B, three-centre, two-electron bonds. Other boron hydrides, such as B5H9, contain B—H—B bonds, but often also involve multicentre bonds in clusters of boron atoms. 

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