Neutral Six-Coordinate Phosphorus

Sterically Restricted Tin Phosphines, Stabilized by Weak Intramolecular Donor–Acceptor Interactions

“…6-diisopropylphosphinoacenaphth-5-yl-tin derivatives 1-4, the bromine-phosphorus precursor 5 and previously reported Sn-P derivative P. 37 ed by transition metals with vacant orbitals or non-metals such as the heavier trivalent group 15 halides. 18,35,36 We postulated that positioning the Lewis-basic P i Pr 2 group across-the-bay from a comparatively electropositive tin functional group would afford sterically restricted systems, stabilized by intramolecular P→Sn donor-acceptor type interactions, similar to the previously reported Sn-P acenaphthene P (Figure 2). 37 In addition, as both peripositions would be accommodated by NMR active nuclei, SSCCs could give a good indication of the extent of non-covalent bonding interactions present in these systems.…”

New Trends in Hexacoordinated Phosphorus Chemistry

“…These compounds can be designated as s 6 , l 6 in which s corresponds to the coordination number and l to the total number of bonds; this last parameter thus representing the valence of phosphorus. In general, hexacoordinated phosphorus adopts (i) an octahedral geometry (Oh) with six identical substituents positioned at same distance and at a 90°angle from each other or (ii) a pseudooctahedral arrangement (D4h) with ligands in two axial and four equatorial positions, respectively.…”

“…This is done by treating PX 3 derivatives (X=halogens, NR 2 , OR f ) with diols to form monocyclic adducts, which are in turn oxidized to bicyclic spirophosphoranes using 6 S. Constant · J. Lacour a-diketones or ortho-quinones as oxidants, and o-chloranil in particular. To carry out the final chelation step, it is sufficient to add a third diol ligand (ligand cc).After nucleophilic displacement of the last substituent X, chelation occurs, usually in the presence of a base, to form the final ring.…”

“…Since this discovery, and now for more than 40 years, chemists interested in organic, inorganic, physical, and applied chemistry have generated compounds based on hexacoordinated phosphorus and studied these many derivatives for a variety of applications. Earlier work was reviewed in 1972 by Hellwinkel [5] and more recent articles are those of Cavell [6] and Holmes [7,8]. Several manuscripts or book chapters have also been written on the topic giving a good -yet slightly outdated -overview of the field [9][10][11][12].…”

“…The flagship of anionic P(VI) chemistry is of course the hexafluorophosphate anion PF 6 -, which is routinely used in all fields of chemistry as a "non-coordinating" counter-ion [14]. In his pioneering work of the 1970s Hellwinkel prepared several anionic phosphates, among which are compounds 1 to 4 ( Fig.…”