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Issue 9, 2010
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Tripodal polyphosphine ligands as inductors of chelate ring-opening processes in mononuclear palladium(ii) and platinum(ii) compounds. The X-ray crystal structure of two derivatives containing dangling phosphorus

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Abstract

The reaction of NP3 (tris[2-(diphenylphosphino)ethyl]amine and PP3 (tris[2-(diphenylphosphino)ethyl]phosphine) with the five-coordinate complexes [PdCl(NP3)]Cl (1) and [MX(PP3)]X [M = Pd: X = Cl(2), Br(3), I(4); M = Pt: X = Cl(5), Br(6), I(7)], respectively, followed by 31P{1H}NMR when X = Cl, led to the formation of unprecedented four-coordinate halides in a 1 : 2 metal to ligand ratio, [M(AP3)2]X2 [A = N, M = Pd: X = Cl(8); A = P, M = Pd: X = Cl(9), Br(10), I(11); A = P, M = Pt: X = Cl(12), Br(13), I (14)], containing reactive dangling phosphorus. Given the non characterised precursors [M(ONO2)(PP3)](NO3)], the interaction between the heteronuclear species [MAg(NO3)3(PP3)] [M = Pd(15), Pt(16)] and PP3 was explored. It was found that the addition of 1 equivalent of phosphine afforded [MAg(NO3)(PP3)2](NO3)2 [M = Pd(15*), Pt(16*)] containing Ag(I) bound to two dangling phosphorus while the reaction with 2 equivalents led to the complexes [M(PP3)2](NO3)2 [M = Pd (17), Pt (18)] in coexistence with [Ag2(μ-PP3)2](NO3)2. The fate of Ag(I) on the reaction of the mixed metal compounds with excess PP3 consisted of preventing dissociation, observed in solution for halides, and acting as an assistant for crystallization. Colourless single crystals of 18 and 10, studied by X-ray diffraction, were afforded by reaction of 16 with 4 equivalents of PP3 and from solutions of 10 in chloroform coexisting with red crystals of 3, respectively. The structures revealed the presence of dications [M(PP3)2]2+ that show two five-membered chelate rings to M(II) in a square-planar arrangement and four uncoordinated phosphine arms with the counter anions being symmetrically placed at 4.431 (Br) and 13.823 (NO3) Å from M(II) above and below its coordination, MP4, plane. Complexes 9 and 12 were shown to undergo an interesting reactivity in solution versus group 11 monocations. The reactions consisted of conversions of the two five-membered chelate rings to M into three (structure I) or two (structure II) fused five-membered chelate rings, formation of species where Pt(II) retained its square-planar environment with the two dangling phosphine arms of each PP3 bound to Cu(I) or Ag(I) (structure III) and complexes bearing distorted square-planar (P2MCl2) and presumably tetrahedral (AuP4+ P2AuCl2) arrangements (structure IV). The processes with Ag(I) salts also gave mixtures of I+III (chloride and nitrate) or II+III (nitrate).

Graphical abstract: Tripodal polyphosphine ligands as inductors of chelate ring-opening processes in mononuclear palladium(ii) and platinum(ii) compounds. The X-ray crystal structure of two derivatives containing dangling phosphorus

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Article information


Submitted
26 Jun 2009
Accepted
20 Nov 2009
First published
18 Jan 2010

Dalton Trans., 2010,39, 2327-2336
Article type
Paper

Tripodal polyphosphine ligands as inductors of chelate ring-opening processes in mononuclear palladium(II) and platinum(II) compounds. The X-ray crystal structure of two derivatives containing dangling phosphorus

D. Fernández-Anca, M. I. García-Seijo and M. E. García-Fernández, Dalton Trans., 2010, 39, 2327
DOI: 10.1039/B912678C

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