A CNDO/2 approach to the electronic structure of phosphabenzenes

Aromatic λ3 heterocycles XIV. Fosfinine-ether macrocyclesheterocycles XIV. Fosfinine-ether macrocycles

“…The energy of molecular orbitals in phosphinine-ether macrocycles are raised with respect to phosphinine, that is in agreement with previous calculations and photoelectron spectra of substituted phosphabenzene and triphosphabenzene [15,17,18,35]. Table 7 HOMO and LUMO energies and HOMO-LUMO gaps calculated with PM3 and MNDO/d methods in comparison with 2,6-bistrimethylsilil phosphinine (eV) [40,41].…”

“…Even if crown ethers and phosphine-ether macrocycles display interesting coordinative behavior towards metals or neutral molecules, due to optical isomerism of phosphorus atoms they posses many practical problems [5][6][7][8][9][10][11][12][13]. The aromatic character of phosphinine was demonstrated earlier by structural and magnetic criteria and also by spectral investigation [14][15][16][17][18]. The exploration of coordinative abilities of phosphinine showed that η 1 coordination is preferred with low oxidation state metals, whereas π-complexes may be obtained with different metallic species [19][20][21][22][23][24][25][26][27].…”

Theory and application of photoelectron spectroscopy. 65. Nature of bonding in .lambda.5-phosphorins

“…Again, the tremendous shift of the in(bi) ionizations of X5-phosphorins toward lower ionization potentials compared to the same ionization of the X3 counterpart is evident. On the contrary, the *-2 (42) ionizations of the X5 compounds occur not far away from the region where this ionization occurs in the X3 case. It is further noteworthy that the substituent (Ri,R2) dependent trends in the shifts of all three relevant ionization regions (^(bi), 2(^2), and Ph) are quite similar.…”

A molecular orbital study of monomeric metaphosphate. Density surfaces of frontier orbitals as a tool in assessing reactivity

“…We have dealt so far only with the inverse relation of reactivity with acceptor orbital energy. Figures 6 through 13 allow us to compare the overlap of the acceptor orbitals in monomeric metaphosphate and in nitrate with a hypothetical donor (the nitrate * level is eliminated as an effective acceptor because of its high energy; it is included only for comparison). Figures 6, 7, 8, and 9 are maps of the total probability density in a plane; Figures 10,11,12, and 13 are the three-dimensional surfaces at which the probability density is 0.01 (au-3).…”