Molecular hydrogen, coordinate bond

The mechanism begins with the dihydride Ir(III) complex 127, and in the first two steps, the olefin coordinates in the trans position with respect to the phosphoms and molecular hydrogen coordinates in the axial position. Simultaneously, the olefin next undergoes a migratory insertion into the axial Ir-H bond, and H2 undergoes oxidative addition. The resulting species 130 is extremely labile with... 

Kubas, G.J., R.R. Ryan, B.N. Swanson, P.J. Vergatini, J. Wasswerman, Molecular hydrogen complexes Coordination of a sigma bond to transition metals.. Am. Chem. Soc. 120,1988. 

A) Dative Hi coordination. Metals with empty orbitals can accept charge from the donor molecular hydrogen. Alternatively, this... 

The network structures to be discussed will all involved hydrogen bonding as the supramolecular synthon. It should be noted however that other interactions such as coordinate bonds and host-guest interactions may also organise host molecules into network structures. Coordination polymers constructed from molecular hosts may involve functionalised calixarenes [8-11], cyclotriveratrylene [12], or cucurbituril [13]. Calixarenes have also been used to build up network structures via host-guest interactions [14,15]. It is also notable that volatile species may be trapped within the solid state lattice of calix[4] arene with a structure entirely composed of van der Waals interactions [16]. 

Carbon and oxygen atom positions were refined with anisotropic thermal parameters. Hydrogen atoms were not located. Figure 3 shows the molecular structure and the atom numbering scheme utilized for the x-ray data presented in the supplementary material for heritiana acetate. Coordinates, bond length, and bond angles for compound III acetate are available as supplementary material. 

---