Phosphine-Based Platinum(II) Hydroxo and Oxo Complexes¹

The platinum(II) hydroxo complexes, [L2Pt(μ-OH)]2(BF4)2 (1), have been prepared from the reaction of L2PtCl2 with AgBF4 for L2 = dppm, dppp, dppb, 2PMe2Ph, and But2bpy (dppm = bis(diphenylphosphino)methane, dppe = bis(diphenylphosphino)ethane, dppp = bis(diphenylphosphino)propane, dppb = bis(diphenylphosphino)butane, But2bpy = 4,4‘-di-tert-butyl-2,2‘-bipyridine). The trifluoroacetate (L2 = dppp) and the nitrate (L2 = But2bpy) salts were also prepared. Two of these new hydroxo complexes, as well as the previously known PPh3 complex, were structurally characterized. Crystals of [(PPh3)2Pt(μ-OH)]2(BF4)2 from CH2Cl2/ether are monoclinic (C2/m) with a = 17.183(5) Å, b = 18.243(4) Å, c = 13.539(4) Å, β = 130.66(2)°, and Z = 2. Crystals of [(dppm)Pt(μ-OH)]2(BF4)2·2DMF from DMF/Et2O are monoclinic (P21/n) with a = 17.193(6) Å, b = 9.341(5) Å, c = 18.666(7) Å, β = 98.73(2)°, and Z = 2. Crystals of [(dppb)Pt(μ-OH)]2(BF4)2·4MeOH from MeOH/Et2O are triclinic (P1̄) with a = 12.547(13) Å, b = 12.858(14) Å, c = 13.039(20) Å, α = 62.89(11)°, β = 63.05(11)°, γ = 60.87(12)°, and Z = 1. The structures of the binuclear dications are all similar, having planar P2Pt(μ-OH)2PtP2 cores with pseudo-D2h symmetry. For all but the dppm complex, addition of 2 equiv of LiN(SiMe3)2 results in deprotonation of the hydroxo groups and formation of the oxo complexes [L2Pt(μ-O)]2. The isolated oxo complexes are associated with one (L = PPh3) or two (L = PMe2Ph; L2 = dppe, dppp, dppb, But2bpy) LiX units (X = BF4 or CF3CO2) by interaction of the oxo ligands with the Li cations. The structure of [(PPh3)2Pt(μ-O)]2·LiBF4 (2) was determined. Crystals of 2·0.5C7H8 from toluene are monoclinic (C2/c), with (173 K) a = 20.469(8) Å, b = 18.085(9) Å, c = 18.152(8) Å, β = 90.34(6)°, and Z = 4. The structure consists of two edge-shared square planar Pt atoms folded at the edge with cis-phosphines and bridging oxygen atoms. The bridging oxo oxygen atoms are coordinated to the Li cation of a LiBF4 contact ion pair. Two fluorine atoms of the BF4 ion also coordinate to the Li cation, resulting in a flattened tetrahedral environment about the Li cation. The oxo complex [(PMe2Ph)2Pt(μ-O)]2·(LiBF4)2 is unstable in solution and converts to the μ3-oxo complex [(L2Pt)3(μ3-O)2](BF4)2 (5) (L = PMe2Ph). Crystals of 5 from THF are orthorhombic (Pbna), with (173 K) a = 16.792(4) Å, b = 17.710(5) Å, c = 19.648(6) Å, and Z = 4. The core structure of the dication consists of a dioxo-bicapped Pt3 triangle. Deprotonation of the dppm hydroxo complex 1 (L2 = dppm) occurs at the dppm methylene group and not at the hydroxo group. The resulting neutral hydroxo complex [(dppm-H)Pt(μ-OH)]2 (6) (dppm-H = bis(diphenylphosphino)methanide) is further deprotonated in THF at the OH group, giving the structurally characterized anionic oxo complex [(dppm-H)Pt(μ-O)]2[Li(THF)2]2 (7). Crystals of 7·4THF from THF are monoclinic (P21/c), with (173 K) a = 10.534(2) Å, b = 21.016(2) Å, c = 18.402(4) Å, β = 103.41(1)°, and Z = 2. The structure has a planar core with the deprotonation of the dppm ligand evident from a shortening of the P−C distances. The Li ions are associated with the oxo groups, not the dppm-H groups, and are each coordinated by two THF molecules, giving a trigonal planar Li coordination geometry

Phosphine-Based Dinuclear Platinum(II) Diamido, Amido−Hydroxo, Oxo−Amido, Oxo−Imido, Diimido, and Dihydrazido Complexes¹

The platinum(II) amido−hydroxo and diamido complexes [(L2Pt)2(μ-NHR)(μ-OH)](BF4)2 (1) (L = PPh3, R = Ph, p-tol, p-ButC6H4, p-NO2C6H4; L2 = dppp, R = Ph, p-tol) and [L2Pt(μ-NHR)]2(BF4)2 (2) (L2 = dppm, R = H, Ph, p-tol, NH2; L2 = dppe, R = H, Ph, p-tol; L2 = dppp, R = H, NH2; L2 = dppb, R = NH2; L = PMe2Ph, R = H) are prepared from the reaction of [L2Pt(μ-OH)]2(BF4)2 with NH2R. [(PPh3)4Pt2(μ-OH)(μ-NHR)](OTf)2 (R = p-NO2C6H4) (1a), the triflate analogue of 1 (L = PPh3, R = p-NO2C6H4), is similarly prepared from [L2Pt(OH2)2](OTf)2. Crystals of 1·CH2Cl2 (L = PPh3, R = p-tol) from CH2Cl2/ether are monoclinic (P21/n) with a = 16.331(5) Å, b = 23.908(5) Å, c = 19.233(6) Å, β = 99.01(1)°, and Z = 4. The cationic portion consists of two edge-shared square-planar Pt centers folded at the edge with cis-phosphines and bridging hydroxo and amido groups. LiN(SiMe3)2, LiNPri2, LiPh, or LiMe addition to 1 (L = PPh3, R = Ph, p-tol, p-ButC6H4) or 1a deprotonates the hydroxo group, forming the amido−oxo complexes [(L2Pt)2(μ-NHR)(μ-O)](BF4) (3) (L = PPh3, R = Ph, p-tol, p-ButC6H4) or [(PPh3)4Pt2(μ-O)(μ-NHR)](OTf) (L = PPh3, R = p-NO2C6H4) (3a). Deprotonation of the diamido complexes 2 (L2 = dppm, R = H, Ph, p-tol, NH2) with LiN(SiMe3)2 yields [(dppm-H)Pt(μ-NHR)]2 (4) (R = H, Ph, p-tol) or [(dppm-H)2Pt2(μ-NHNH2)2Li(THF)2]BF4 (5). Crystals of 4 (R = Ph) from CH2Cl2/ether are (183 K) orthorhombic (Pna21) with a = 38.272(2) Å, b = 9.2841(5) Å, c = 15.0099(7) Å, and Z = 4. The structure consists of two edge-shared square-planar Pt centers folded at the edge with syn-bridging amido groups and chelating dppm-H ligands. Crystals of 5·5THF from THF are (183 K) monoclinic (P21/n) with a = 17.669(5) Å, b = 31.884(3) Å, c = 14.686(4) Å, β = 105.03(1)°, and Z = 4. The structure of the cationic portion shows two edge-shared square-planar Pt centers folded at the edge with syn-bridging NHNH2 groups and chelating dppm-H ligands. The NHNH2 groups bridge the Pt centers through the NH portion. The NH2 portions coordinate to a Li(THF)2+ group in a “tweezers” fashion resulting in tetrahedral coordination about the Li atom. Further deprotonation of 4 with LiMe yields the anionic diimido complexes [(dppm-H)Pt(μ-NR)]2(Li)2 (6) (R = H, Ph, p-tol)

Associations (univariate analysis) between the prevalence of severe snoring and ocular and systemic parameters in the Beijing Eye Study 2011.

<p>Associations (univariate analysis) between the prevalence of severe snoring and ocular and systemic parameters in the Beijing Eye Study 2011.</p

Associations (multivariate analysis) between the prevalence of severe snoring and ocular and systemic parameters in the Beijing Eye Study 2011.

<p>Associations (multivariate analysis) between the prevalence of severe snoring and ocular and systemic parameters in the Beijing Eye Study 2011.</p

Fundus photograph showing the optic disc—fovea line (black line), outer border of parapapillary alpha zone (white arrows) and the outer border of parapapillary beta (gamma) zone (red arrows).

<p>Fundus photograph showing the optic disc—fovea line (black line), outer border of parapapillary alpha zone (white arrows) and the outer border of parapapillary beta (gamma) zone (red arrows).</p

Associations (Multivariate Analysis) between the Bruch’s Membrane Opening-Fovea-Distance and Ocular and Systemic Parameters in Non-Glaucomatous Individuals with an Axial Length of ≥23.5 mm in the Beijing Eye Study 2011.

<p>Associations (Multivariate Analysis) between the Bruch’s Membrane Opening-Fovea-Distance and Ocular and Systemic Parameters in Non-Glaucomatous Individuals with an Axial Length of ≥23.5 mm in the Beijing Eye Study 2011.</p

Associations (Univariate Analysis) between the Disc-Fovea-Angle and Ocular and Systemic Parameters in the Beijing Eye Study 2011.

<p>Associations (Univariate Analysis) between the Disc-Fovea-Angle and Ocular and Systemic Parameters in the Beijing Eye Study 2011.</p

Distribution of the Disc-Fovea Distance.

<p>Distribution of the Disc-Fovea Distance.</p

Histogram Showing the Distribution of the Optic Disc—Fovea Angle in the Beijing Eye Study 2011.

<p>Histogram Showing the Distribution of the Optic Disc—Fovea Angle in the Beijing Eye Study 2011.</p

Associations (Multivariate Analysis) between the Bruch’s Membrane Opening-Fovea-Distance and Ocular and Systemic Parameters in Non-Glaucomatous Individuals with an Axial Length of <23.5 mm in the Beijing Eye Study 2011.

<p>Associations (Multivariate Analysis) between the Bruch’s Membrane Opening-Fovea-Distance and Ocular and Systemic Parameters in Non-Glaucomatous Individuals with an Axial Length of <23.5 mm in the Beijing Eye Study 2011.</p