Anti-bonding character

One-electron oxidation to [Rh2(OCOMe)4(H20)2]+ leads to an ion (violet to orange, depending on solvent) with a shorter Rh-Rh bond (2.317 A) than that in the neutral molecule (2.385 A), suggesting the electron has been removed from an orbital with anti-bonding character. 

In contrast to chloride compounds, niobium oxides have a VEC of 14 electrons, due to an overall anti-bonding character of the a2u state, caused by a stronger Nb-O anti-bonding contribution. In some cases, the VEC cannot be determined unambiguously due to the uncertainty in the electron distribution between the clusters and additional niobium atoms present in the majority of the structures. The 14-electron compounds exhibit semiconducting properties and weak temperature-independent paramagnetism. Unlike niobium chlorides, the oxides do not exhibit a correlation between the electronic configuration and intra-cluster bond distances. 

An ab initio molecular orbital calculation was made on the tetratelluronaphthalene 3 <2005EJI3435>. The highest occupied molecular orbital (HOMO) was found to have anti-bonding character in the Te-Te bond. 

The interaction of the terminal parts of the HOMO having anti-bonding character contributes to make the cis form unstable relative to trans. 

Furthermore, the results support that NO photodesorption and decay of a dimer itself should be competing channels because the introduced resonant orbital is the only one for a dimer which has anti-bonding character for both N—O and NO—NO. This is consistent with the experimental results that N20 desorption is also observed by substrate-mediated excitation, and its action spectrum exactly mirrors that for NO photodesorption. Again we emphasize our results and analyses are obtained by ah iniio calculations within the model of NEGF-DFT focusing on hot electron transport and a charge injection process. This is an example to show the importance and... 

The photoelectron spectrum of a molecule is closely related to the set of occupied valence orbitals. For simple molecules, some PE bands show discrete structure due to vibrational excitation of the ion this can be interpreted in terms both of the bonding/non-bonding/anti-bonding character of the electron removed and of the vibration frequencies of the ion, as described in the last section. All of this information is related to... 

The Cobalt Triad.— The first example of a paramagnetic octahedral cluster, [COeC(CO)i4], shows uneven lengthening of cobalt-cobalt bonds indicative of the anti-bonding character of the extra electron. Transition-metal carbonyls, particularly ICo2(CO)8l catalyse the conversion of CO and H2 at moderate temperatures and pressures into ethanol and other oxygenated products. Parameters obtained by a complete Wolfsberg-Helmholtz (Extended Hiickel) MO analysis of [CoMe(CO)4] have been fitted to the measured u.v. absorption bands. Products from the co-condensation of cobalt vapour with cyclo-pentadiene and various acetylenes include (8—11). ... 

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