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

Abstract

The reaction of NP(3) (tris[2-(diphenylphosphino)ethyl]amine and PP(3) (tris[2-(diphenylphosphino)ethyl]phosphine) with the five-coordinate complexes [PdCl(NP(3))]Cl (1) and [MX(PP(3))]X [M = Pd: X = Cl(2), Br(3), I(4); M = Pt: X = Cl(5), Br(6), I(7)], respectively, followed by (31)P{(1)H}NMR when X = Cl, led to the formation of unprecedented four-coordinate halides in a 1 : 2 metal to ligand ratio, [M(AP(3))(2)]X(2) [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(ONO(2))(PP(3))](NO(3))], the interaction between the heteronuclear species [MAg(NO(3))(3)(PP(3))] [M = Pd(15), Pt(16)] and PP(3) was explored. It was found that the addition of 1 equivalent of phosphine afforded [MAg(NO(3))(PP(3))(2)](NO(3))(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(PP(3))(2)](NO(3))(2) [M = Pd (17), Pt (18)] in coexistence with [Ag(2)(mu-PP(3))(2)](NO(3))(2). The fate of Ag(I) on the reaction of the mixed metal compounds with excess PP(3) 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 PP(3) and from solutions of 10 in chloroform coexisting with red crystals of 3, respectively. The structures revealed the presence of dications [M(PP(3))(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 (NO(3)(-)) A from M(II) above and below its coordination, MP(4), 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 PP(3) bound to Cu(I) or Ag(I) (structure III) and complexes bearing distorted square-planar (P(2)MCl(2)) and presumably tetrahedral (AuP(4)+ P(2)AuCl(2)) arrangements (structure IV). The processes with Ag(I) salts also gave mixtures of I+III (chloride and nitrate) or II+III (nitrate).

Dibismuthates as Linking Units for Bis-Zwitterions and Coordination Polymers

“…On the other hand, the number of bond critical points representing the interactions suggests a coordination number of 5. In analogy with the limited number of reported examples with 5-coordinated silver centers, − we therefore describe the silver centers in the [Ag­( PS 3 )] 2 2+ units as 5-coordinated. The structural parameter value of τ 5 = 0.47 indicates that the coordination around the silver atom is intermediate between trigonal bipyramidal and square pyramidal. , …”

Tuneable reactivity with PPh3 and SnX2 of four- and five-coordinate Pd(ii) and Pt(ii) complexes containing polyphosphines

“…5, 66.3, 30.5 and δ 53.3, 42.7, 29.7, respectively, with an 1 : 1.2 integration ratio attributed to P D : P E : P F (Scheme S1 †). The 1 J( 10 The reaction of iodides 5a and 6a with two equivalents of SnI 2 proceeds in air in the presence or absence of PPh 3 giving the unusual neutral compounds 9•3H 2 O and 10•3H 2 O, where PP 3 is acting as a bidentate ligand through the central and one terminal P with the remaining two P being oxidised and bound to SnI 2 moieties. The conductivity measurements for 9•3H 2 O in DMF (0.2 ohm −1 cm 2 mol −1 ) confirm the non-electrolyte behaviour.…”

“…S5, Scheme S1 †) confirms the same structure in solution with 1 J( 31 P D -195 Pt) = 2254 Hz < 1 J( 31 P E -195 Pt) = 2402 Hz in the expected range. 10 The rare neutral iodo complex 9 was also afforded in solution in coexistence with the unexpected oxidised forms [PdI 2 (PP(PO) 2 )] ( 9…”