Bond length

About: Bond length is a research topic. Over the lifetime, 19966 publications have been published within this topic receiving 498004 citations.

Empirical bond-strength–bond-length curves for oxides

Abstract: Bond-strength-bond-length relationships for bonds between oxygen and H+, Li+, Be2+, B3+, Na+, Mg2+, Al3+, Si4+, P5+, S6+, K+, Ca2+, Sc3+, Ti4+, V5+, Cr6+, Mn2+, Fe3+, Fe2+, Co2+, Cu2+, Zn2+, Ga3+, Ge4+ and As5+ have been derived by requiring that the sums of the bond strengths around the cations be equal to their valence in 417 crystals whose structures have been accurately determined. The relationship is of the form s = (R/R0)-N where s = bond strength, R = bond length and R0 and N are fitted constants. It is further shown that all ions with an isoelectronic core can be fitted by a single pair of parameters, R0 and N, that are independent of the ionic character of the bond and the coordination number of the cation. The resulting bond strengths have the property that they are directly related to the covalent character of the bond and that their sum around each atom is, on average, within about 5% of its valence. The bond-strength-bond-length curves are particularly useful in accounting for bonding in cases where the coordination is very distorted (e.g. Na+, Cu2+ and V5+). They can also be used to predict the positions of hydrogen atoms, to analyze for different oxidation states and site occupancies, to calculate ionic radii and to provide an indication of the correctness of crystal structure determinations.

Supplement. Tables of bond lengths determined by X-ray and neutron diffraction. Part 2. Organometallic compounds and co-ordination complexes of the d- and f-block metals

Abstract: Average lengths for metal–ligand bonds are reported, together with some intraligand distances, for complexes of the d- and f-block metals. Mean values are presented for 325 different bond types involving metal atoms bonded to H, B, C, N, O, F, Si, P, S, Cl, As, Se, Br, Te, or I atoms of the ligands.

Three methods to measure RH bond energies

Abstract: We present a critical review of three different experimental methods used to measure bond energies: radical kinetics, gas-phase acidity cycles, and photoionization mass spectrometry. These experimental techniques are currently in use to measure the bond energies of a large number of molecules. We discuss the basic premises of each of these experiments and explicitly try to point out the strengths and weaknesses of each method. We directly compare each of these procedures using a set of about 30 important molecules. These three different techniques have only a few disagreements among them, the case of ethylene being the most serious. For the overwhelming number of studies, all measurements lead to bond energies within each other's error bars. We include tables of ionization potentials, electron affinities, and heats of formation for about 40 important organic and inorganic radicals. We also list bond energies for the parent molecules at 0 and 298 K. 273 refs., 10 figs., 5 tabs.

Molecular Double-Bond Covalent Radii for Elements Li–E112

Abstract: The previous systems of triple-bond and single-bond self-consistent, additive covalent radii, R(AB)=r(A)+ r(B), are completed with a fit for σ2π2 double-bonds.The primary bond lengths, R, are taken from experimental or theoretical data corresponding to chosen group valencies. All r(E) values are obtained from the same, self-consistent fit. Many of the calculated primary data came from ECH2 and HECH2 models. Homonuclear LEEL, formaldehyde-type Group 14–Group 16 and open-shell, X3 Σ Group-16 dimer data are included. The standard deviation for the 316 included data points is 3 pm.