Synthesis and characterization of triarylphosphine complexes of zinc(II) halides

Abstract

Both 1 : 1 and 1 : 2 complexes are formed by zinc(II) halides and triarylphosphines unless electronic and/or steric factors intervene. Tri-p-chlorophosphine (a weaker base than PPh 3 ) forms only a 1 : 1 complex, whereas bulky tri-(ortho-substituted phenyl)phosphines do not react. The complexes ZnX 2 PR 3 and ZnX 2 (PR 3 ) 2 have been characterized by elemental analyses, conductance, far-IR and (in a few cases) Raman spectral studies. The Zn-X and Zn-P stretching and Zn-X bending vibrational frequencies have been assigned in the complexes with a pseudo-tetrahedral structure of C 2v symmetry.

Gold(I)‐Catalyzed Intramolecular Cyclopropanation of Dienynes

“…With other bulky phosphanes, in addition to tetracycle 15 , the skeletal rearrangement product 16 was obtained as the major compound, along with Alder‐ene cycloisomerization derivative 17 2a,b (Table 2, entries 3–5). Interestingly, although Zn II has seldom been used in enyne cyclizations,20 we found that 9 reacted in the presence of [ZnCl 2 (PPh 3 )]21 and AgSbF 6 (50 mol % each) in 1,2‐dichloroethane at room temperature to afford a mixture of tetracycle 15 and skeletal rearrangement product 16 , although the yield of isolated product was low (Table 2, entry 6). With [ZnCl 2 (PPh 3 )] or Zn(OTf) 2 in the absence of Ag I , 16 was obtained along with other uncharacterized compounds (Table 2, entries 7–9).…”

Coordination chemistry of the main group elements with phosphine, arsine and stibine ligands

“…Few anionic [ZnX 3 (PR 3 )] − species are known, probably more due to the lack of attempts to prepare them than inherent instability, but two have been structurally characterised [31,32]. Direct reaction of zinc halides with phosphines in a 1:2 molar ratio in diethyl ether, ethanol or THF solution usually results in the formation of [ZnX 2 (PR 3 ) 2 ] (R = Me, Ph, pMeC 6 H 4 , p-MeOC 6 H 4 ) [30,[33][34][35], although P(p-ClC 6 H 4 ) 3 gave only 1:1 complexes, and P(o-MeC 6 H 4 ) 3 or P(o-MeOC 6 H 4 ) 3 failed to complex at all with ZnBr 2 [34]. An alternative synthetic approach is the reaction of zinc powder with R 3 PI 2 , which in most cases forms the 1:1 adducts [Zn 2 I 2 (-I) 2 [37].…”