Phosphorus electronic structure

The EPR spectra of the related 1,2,4,6,3,5-thiatriazadiphosphinyl radicals (3.20) reveal a distinctly different electronic structure.The observed spectrum consists of a quintet of triplets consistent with coupling of the unpaired electron with two equivalent nitrogen atoms and two equivalent phosphorus atoms [Fig. 3.4(a)]. This interpretation was confirmed by the observation that the quintet collapses to a 1 2 1 triplet when the nitrogen atoms in the ring are 99% N-enriched [Fig 3.4(b)]. Thus the spin delocalization does not extend to the unique nitrogen atom in the phosphorus-containing system 3.20. 

Dechnicke K, Shihada A-F (1976) Structural and Bonding Aspects in Phosphorus Chemistry-Inorganic Derivates of Oxohalogeno Phosphoric Acids. 28 51-82 Denning RG (1992) Electronic Structure and Bonding in Actinyl Ions. 79 215-276 Dhubhghaill OMN, Sadler PJ (1991) The Structure and Reactivity of Arsenic Compounds. 

The electron structure of phosphorus ends with 3s2 3p3 3d°. As we saw previously, the phosphorus atom normally forms three bonds. However, it is able to undergo sp3d hybridization as shown below. 

The reaction of the stannane (176) with phosphorus trichloride gives the phosphorin (177). The electron-donating methyl group reinforces the ring dipole, the negative end of which is the phosphorus atom.189 The dibenzo analogue (178) has also been prepared and its electronic structure studied by photoelectron spectroscopy.160... 

Carbocations have similar electronic structures to carbenes. The P-protonated derivative of phosphinine should also be similar to 23. Indeed, while investigating the proton affinity of 3. the most preferred protonation site was phosphorus and not carbon, whereby the cyclic jt system would be interrupted. ... 

A. Specific Features of the Electronic Structure of Nitrogen and Phosphorus... 

Triazaphospholes are related to 1,2,4-triazoles by a CH/P exchange and to tetrazoles by a N/P exchange they have been compared to these analogues with respect to their electronic structure and NMR spectra <89JCR(S)250>. The 1H-, 2H- and 4//-l,2,4,3-triazaphospholes differ considerably in their behavior. 1,2,4,32 -Triazaphospholes, -oxadiazaphospholes and -thia-diazaphospholes are covered in a review on cyclophosphazanes with five- and six-coordinate phosphorus . 

A couple of theories have been proposed to explain how dietary Ca might possibly affect Se utilization. It has been suggested that Se availability may be directly influenced by intestinal interactions involving Ca or minerals linked to Ca utilization (e.g., phosphorus) (Lowry et al., 1985). Indirect effects on the capacity of a target tissue to respond to Se are also considered possible means by which bioavailability or retention might be influenced (Parizek, 1978). It has also been conjectured (Hill and Matrone, 1970 Howell and Hill, 1978) that elements with valence shell electronic structures most similar to Se (i.e., Se , Se, and Se " ") are most likely to act antagonistically. Based on this criterion, Ca does not fit the profile of a probable Se antagonist. 

Molecular orbital theory may provide an explanation for stereochemical differences between carboxylate-metal ion and phosphate-metal ion interactions. Detailed ab initio calculations demonstrate that the semipo-lar 1 0 double bond of RsP=0 is electronically different from the C=0 double bond, for example, as found in H2C=0 (Kutzelnigg, 1977 Wallmeier and Kutzelnigg, 1979). The P=0 double bond is best described as a partial triple bond, that is, as one full a bond and two mutually perpendicular half-7r bonds (formed by backbonding between the electrons of oxygen and the empty d orbitals of phosphorus). Given this situation, a lone electron pair should be oriented on oxygen nearly opposite the P=0 bond, and these molecular orbital considerations for P=0 may extend to the phosphinyl monoanion 0-P=0. If this extension is valid, then the electronic structure of 0-P=0 should not favor bidentate metal complexation by phosphate this is in accord with the results by Alexander et al. (1990). 

A fascinating feature of the chemistry of boron-phosphorus heterocycles is the existence of stable singlet biradicals, e.g. fBuBP Pr2)2 (for a discussion of the electronic structure, see Section 5.4.2.2). The synthesis of this four-membered ring is illustrated in Scheme 5.2. Related derivatives of the type (RBPR 2)2 are also prepared by a salt-elimination reaction of the appropriate lithium phosphide with a 1,2-dichlorodiborane or, in the case of the perphenylated derivative (PhBPPh2)2, by reduction of the cyclic dimer [Ph(Cl)BPPh2]2 with lithium naphthalenide (Scheme 9.11). ... 

---