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Palladium(II) and Platinum(II) Complexes of the Heterodifunctional Ligand Ph 2 PNHP(O)Ph 2

1996; American Chemical Society; Volume: 35; Issue: 12 Linguagem: Inglês

10.1021/ic951247d

1520-510X

Pravat Bhattacharyya, Alexandra M. Z. Slawin, Martin B. Smith, J. Derek Woollins,

Metal complexes synthesis and properties

The noncomplexed ligand Ph2PNHP(O)Ph2 (HL) has been prepared, for the first time, from Ph2PNHPPh2 (dppa) and H2O2 in moderate yield. On further treatment with H2O2 the phosphine oxide Ph2P(O)NHP(O)Ph2 (1) can be formed. Reaction of [MCl2(COD)] (M = Pt or Pd; COD = cycloocta-1,5-diene) with 2 molar equiv of HL affords [MCl2(HL)2] (4, 5) in which both ligands are monodentate P-bound. The analogous dibromo and diiodo derivatives [MX2(HL)2] (6−9) were prepared from either [MX2(COD)] (M = Pt or Pd; X = Br or I) and HL or treatment of [MCl2(HL)2] with an excess of NaI. Facile base deprotonation of the amine proton in 4 or 5 affords a new class of metallacycles [M(L)2] [L- = Ph2PNP(O)Ph2-] (10, 11) incorporating two five-membered M−P−N−P−O rings. Compound 10 was independently made from [Pt(CH3)2(COD)] and 2 equiv of HL in toluene at ambient temperature whereas the reaction of [Pt(CH3)Cl(COD)] with 2 equiv of HL affords solely trans-[Pt(CH3)Cl(HL)2] (13). Protonation of the neutral compound 10 with HCl in ethanol regenerates the ring-opened cis complex 4. In contrast, addition of HBF4·OEt2 to 10 (or 11) results in exclusive protonation at the nitrogen atom of the chelating ligands to give cis-[M{Ph2PNHP(O)Ph2-P,O}2][BF4]2 (15, 16); both chelate rings remain intact. The dicationic compounds 15, 16 can also be synthesized from 4, 5 in dichloromethane using Ag[BF4] as a chloride abstractor. All new compounds described have been characterized by a combination of multinuclear NMR spectroscopy, IR spectroscopy, and elemental analyses. The molecular structures of Ph2PNHP(O)Ph2, cis-[PtBr2{Ph2PNHP(O)Ph2-P}2], cis-[Pt{Ph2PNP(O)Ph2-P,O}2], trans-[Pt(CH3)Cl{Ph2PNHP(O)Ph2-P}2] and cis-[Pt{Ph2PNHP(O)Ph2-P,O}2][BF4]2 have been determined by single-crystal X-ray diffraction. Crystals of HL are triclinic, space group P1̄, with a = 10.410(2) Å, b = 12.083(2) Å, c = 9.036(4) Å, α = 103.05(2)°, β = 99.09(2)°, γ = 72.98(1)°, V = 1054 Å3, and Z = 2. The final R and Rw values were 0.061 and 0.047, respectively. Crystals of 6 are triclinic, space group P1̄, with a = 13.113(4) Å, b = 15.996(4) Å, c = 13.011(4) Å, α = 102.65(3)°, β = 117.39(2)°, γ = 101.03(2)°, V = 2225 Å3, and Z = 2. The final R and Rw values were 0.039 and 0.031, respectively. Crystals of 10 are monoclinic, space group P21/a, with a = 17.600(13) Å, b = 13.498(10) Å, c = 18.641(9) Å, β = 105.13(1)°, V = 4274 Å3, and Z = 4. The final R and Rw values were 0.041 and 0.036, respectively. Crystals of 13 are triclinic, space group P1̄, with a = 14.686(2) Å, b = 18.735(2) Å, c = 9.018(3) Å, α = 91.71(2)°, β = 102.27(2)°, γ = 68.54(1)°, V = 2253 Å3, and Z = 2. The final R and Rw values were 0.041 and 0.044, respectively. Crystals of 15 are orthorhombic, space group P21212, with a = 14.100(2) Å, b = 19.002(1) Å, c = 9.145(2) Å, V = 2450 Å3, and Z = 2. The final R and Rw values were 0.052 and 0.057, respectively. The P-bound monodentate complexes contain ligands with similar bond lengths to the neutral compound, while deprotonation/chelation results in lengthening of the P−O and shortening of the P−N bond length as a result of electronic delocalization.