Intramolecular bond parameters

Correlation studies on intramolecular bonding parameters were a great success in structural chemistry [6]. In a natural extension, statistical studies of the geometrical parameters of intermolecular bonding began to appear in an attempt to rationalize the complex phenomena of molecular recognition and condensation. Not unexpectedly, success in this latter task was much less immediate. 

Intramolecular reactions usually dominate intermolecular addition for favorable ring sizes. Semiempirical (AMI) calculations found the intramolecular TS favorable to a comparable intermolecular reaction.68 (See Figure 4.1) The intramolecular TS, which is nearly 4 kcal/mol more stable, is quite productlike with a C—O bond distance of 1.6 A, and a bond order of 0.62. The bromonium ion bridging is unsymmetrical and fairly weak. The bond parameters for the intra- and intermolecular TSs are quite similar. 

The discussions of the structure and the electron density are based on the structure found by a full multipole refinement of the X-ray data with the hydrogen positions fixed at the neutron values and the hydrogen thermal parameters fixed at scaled neutron values (Figure 5).1 The interatomic distances and intramolecular bond angles are given in Table 2. 

Acetylacetone was deprotonated with diethylzinc in toluene to afford [EtZn(acac)]2 (Figure 65, 140) which crystallized in dimeric form. The quality of the X-ray data was too low to obtain reliable bond parameters, but the coordination environment about zinc is distorted tetrahedral, with two intramolecular and one intermolecular Zn-O bond.200... 

Microwave spectroscopy is probably the ultimate tool to study small alcohol clusters in vacuum isolation. With the help of isotope substitution and auxiliary quantum chemical calculations, it provides structural insights and quantitative bond parameters for alcohol clusters [117, 143], The methyl rotors that are omnipresent in organic alcohols complicate the analysis, so that not many alcohol clusters have been studied with this technique and its higher-frequency variants. The studied systems include methanol dimer [143], ethanol dimer [91], butan-2-ol dimer [117], and mixed dimers such as propylene oxide with ethanol [144]. The study of alcohol monomers with intramolecular hydrogen-bond-like interactions [102, 110, 129, 145 147] must be mentioned in this context. In a broader sense, this also applies to isolated ra-alkanols, where a weak Cy H O hydrogen bond stabilizes certain conformations [69,102]. Microwave techniques can also be used to unravel the information contained in the IR spectrum of clusters with high sensitivity [148], Furthermore, high-resolution UV spectroscopy can provide accurate structural information in suitable systems [149, 150] and thus complement microwave spectroscopy. 

One structural parameter of potential interest in the adsorption of simple diatomic molecules, such as CO, NO and N2, is the intramolecular bondlength. Much of the motivation for studying such adsorbates is related to the way adsorption modifies the chemistry of these species as the basis for heterogeneous catalysis. Many such reactions involve scission of the intramolecular bond, and if the adsorption is of the... 

Direct methods. The charge per molecule is measured either directly (e.g., very accurate structural determination, x-ray photoelectron spectroscopy) or through the relative change of an intramolecular parameter sensitive to the charge (e.g., intramolecular bond length, intramolecular vibration frequency). The accuracy is relatively poor ( 10%). 

In the present paper we describe the results of X-ray and TOF neutron diffracBon and Raman scattering measurements for aqueous sulfuric acid soluBons with extended composIBon range in order to obtain the intermaBon both on the intermolecular hydrogen-bonded stmcture and on the intramolecular stmctural parameters of SO4 unit in the solutions. 

In Section V.B. a very efficient Intramolecular quenching of 02 was described, whereby 02 molecules approaching both sides of 1-02 actlve site of the acceptor molecule could be readily encountered with Intramolecularly bonded tertiary amino groups. Paquette et al. (227) Investigated recently a heretofore unexplored parameter of singlet oxygen behavior—that Is,... 

---