TY - JOUR
T1 - Synthesis and reactivity of cyclo-tetra(stibinophosphonium) tetracations: redox and coordination chemistry of phosphine-antimony complexes.
AU - Chitnis, Saurabh S.
AU - Robertson, Alasdair P. M.
AU - Burford, Neil
AU - Weigand, Jan J.
AU - Fischer, Roland.
N1 - M1 - Copyright (C) 2017 American Chemical Society (ACS). All Rights Reserved.
CAPLUS AN 2015:196473(Journal; Online Computer File)
PY - 2015
Y1 - 2015
N2 - Reductive elimination of [R3PPR3]2+, [11(R)]2+, from the highly electrophilic SbIII centers in [(R3P)3Sb]3+, [8(R)]3+, gives SbI contg. cations [(R3P)Sb]1+, [9(R)]1+, which assemble into frameworks identified as cyclo-tetra(stibinophosphonium) tetracations, [(R3P)4Sb4]4+, [10(R)]4+. A phosphine catalyzed mechanism is proposed for conversion of fluoroantimony complexes [(R3P)2SbF]2+, [7(R)]2+, to [10(R)]4+, and the characterization of key intermediates is presented. The results constitute evidence of a novel ligand activation pathway for phosphines in the coordination sphere of hard, electron deficient acceptors. Characterization of the assocd. reactants and products supports earlier, albeit less definitive, detection of analogous phosphine ligand activation in CuIII and TlIII complexes, demonstrating that these prototypical ligands can behave simultaneously as reducing agents and σ donors towards a variety of hard acceptors. The reactivity of the parent cyclo-tetra(stibinophosphonium) tetracation, [10(Me)]4+, is directed by high charge concn. and strong polarization of the P-Sb bonds. The former explains the obsd. facility for reductive elimination to yield elemental antimony and the latter enabled activation of P-Cl and P-H bonds to give phosphinophosphonium cations, [Me3PPR'2]1+, including the first example of an H-phosphinophosphonium, [(Me3P)P(H)R']1+, and 2-phosphino-1,3-diphosphonium cations, [(Me3P)2PR']2+. Exchange of a phosphine ligand in [10(Me)]4+ with [nacnac]1- gives [(Me3P)3Sb4(nacnac)]3+, [15(Me)]3+, and with dmap gives [(Me3P)3Sb4(dmap)]4+, [16]4+. The lability of P-Sb or Sb-Sb interactions in [10(Me)]4+ has also been illustrated by characterization of heteroleptically substituted derivs. featuring PMe3 and PEt3 ligands. [on SciFinder(R)]
AB - Reductive elimination of [R3PPR3]2+, [11(R)]2+, from the highly electrophilic SbIII centers in [(R3P)3Sb]3+, [8(R)]3+, gives SbI contg. cations [(R3P)Sb]1+, [9(R)]1+, which assemble into frameworks identified as cyclo-tetra(stibinophosphonium) tetracations, [(R3P)4Sb4]4+, [10(R)]4+. A phosphine catalyzed mechanism is proposed for conversion of fluoroantimony complexes [(R3P)2SbF]2+, [7(R)]2+, to [10(R)]4+, and the characterization of key intermediates is presented. The results constitute evidence of a novel ligand activation pathway for phosphines in the coordination sphere of hard, electron deficient acceptors. Characterization of the assocd. reactants and products supports earlier, albeit less definitive, detection of analogous phosphine ligand activation in CuIII and TlIII complexes, demonstrating that these prototypical ligands can behave simultaneously as reducing agents and σ donors towards a variety of hard acceptors. The reactivity of the parent cyclo-tetra(stibinophosphonium) tetracation, [10(Me)]4+, is directed by high charge concn. and strong polarization of the P-Sb bonds. The former explains the obsd. facility for reductive elimination to yield elemental antimony and the latter enabled activation of P-Cl and P-H bonds to give phosphinophosphonium cations, [Me3PPR'2]1+, including the first example of an H-phosphinophosphonium, [(Me3P)P(H)R']1+, and 2-phosphino-1,3-diphosphonium cations, [(Me3P)2PR']2+. Exchange of a phosphine ligand in [10(Me)]4+ with [nacnac]1- gives [(Me3P)3Sb4(nacnac)]3+, [15(Me)]3+, and with dmap gives [(Me3P)3Sb4(dmap)]4+, [16]4+. The lability of P-Sb or Sb-Sb interactions in [10(Me)]4+ has also been illustrated by characterization of heteroleptically substituted derivs. featuring PMe3 and PEt3 ligands. [on SciFinder(R)]
KW - cyclotetrastibinophosphonium tetracation prepn reactivity
KW - phosphine antimony complex prepn reactivity crystal mol structure
KW - phosphonium complex prepn crystal mol structure reactivity
U2 - 10.1039/C4SC03939D
DO - 10.1039/C4SC03939D
M3 - Article
SN - 2041-6520
VL - 6
SP - 2559
EP - 2574
JO - Chemical Science
JF - Chemical Science
IS - 4
ER -