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The term agostic is reserved to describe two-electron, three-center bonding interactions between carbon, hydrogen, and a metal. Two-electron three-center bonding is clearly implicated in the complexation of H 2 , e.g., in W(CO) 3 (PCy 3 ) 2 H 2 , which is closely related to the agostic complex shown in the figure. [ 8 ]
This species then binds to an alkane molecule, forming a σ-complex (coordination of a C-H bond). In a third step, the metal atom inserts into the C-H bond, cleaving it and yielding the alkyl (or aryl) metal hydride. The intermediates and their kinetics can be observed using time-resolved spectroscopic techniques (e.g. TR-IR, TR-XAS, TR-RIXS ...
Consequently, hydrogen bonds between or within solute molecules dissolved in water are almost always unfavorable relative to hydrogen bonds between water and the donors and acceptors for hydrogen bonds on those solutes. [44] Hydrogen bonds between water molecules have an average lifetime of 10 −11 seconds, or 10 picoseconds. [45]
Bond strength is less than 1 kcal/mol. In the case of aromatic C–H donors, C–H···O interactions are not linear due to influence of aromatic ring substituents near the interacting C-H group. [ 6 ] [ 7 ] If aromatic molecules involved in С–Н···О interaction belong to the group of polycyclic aromatic hydrocarbons , the strength of C ...
The length of the carbonhydrogen bond varies slightly with the hybridisation of the carbon atom. A bond between a hydrogen atom and an sp 2 hybridised carbon atom is about 0.6% shorter than between hydrogen and sp 3 hybridised carbon. A bond between hydrogen and sp hybridised carbon is shorter still, about 3% shorter than sp 3 C-H.
Hydrogen bonds of the form A--H•••B occur when A and B are two highly electronegative atoms (usually N, O or F) such that A forms a highly polar covalent bond with H so that H has a partial positive charge, and B has a lone pair of electrons which is attracted to this partial positive charge and forms a hydrogen bond. [23]: 702 Hydrogen ...
The MO diagram for dihydrogen. In the classic example of the H 2 MO, the two separate H atoms have identical atomic orbitals. When creating the molecule dihydrogen, the individual valence orbitals, 1s, either: merge in phase to get bonding orbitals, where the electron density is in between the nuclei of the atoms; or, merge out of phase to get antibonding orbitals, where the electron density ...
By some definitions, "organic" compounds are only required to contain carbon. However, most of them also contain hydrogen, and because it is the carbon-hydrogen bond that gives this class of compounds most of its particular chemical characteristics, carbon-hydrogen bonds are required in some definitions of the word "organic" in chemistry. [12]