The diplatinum(II1) complex [Pt2(p-P0,H)4(H20)2]2-reacts with halide ions X-(X = CI, Br) to give first [Pt2(p-PO4H),X(H20I3-and then [Pt2(p-P0,H)4X2]4-. The reaction establishes an equilibrium situation between the three complexes:Using pseudo-first-order conditions in halide ion at 25 "C, we have used a biphasic analysis to evaluate the rate constants. The values are k , = 0.9 (2) M-' s-,, k2 = 5 ( I ) X s-' (X = CI) and k , = 0.3 (1) M-I s-l, k2 = 1.5 (3) X s-' (X = Br). Under comparable conditions of temperature (25 "C), pH (3.0), and ionic strength (0.1 M), we have measured the equilibrium constants as K , = 19 (2) M-I, K2 = 11 ( I ) M-' (X = CI) and K2 = 21 (2) M-', K2 = 22 (2) M-' (X = Br). In all cases, k , > k2 and k , > k,, and
The title complex was isolated as a red solid from the reaction of 4-(salicylaldiminato)antipyrine, HL, and cobalt (II) acetate in ethanol. The complex has been characterized by elemental analysis, FTIR, UV-Vis, and X-ray single crystal diffraction. Two crystallographically different cationic units, A and B, of the title complex are found. Both units are essentially isostructural; nevertheless, small differences exist between them. Both units contain four cobalt atoms arranged at the corners of distorted cubane-like core alternatively with phenoxy oxygen of the Schiff base. In both cases, one cobalt binds to three coordinated sites from the corresponding tridentate Schiff base ligand, and the fourth one was bonded by the acetate oxygen, and the fifth and the sixth donor sites come from the phenolate oxygen of another Schiff base ligand.
The mixed Co(II)/Ni(II) complex, [Co2.67Ni1.33L4(CH3COO)2][BPh4]2·0.75H2O where HL = 4-(salicylaldimine)antipyrine, was isolated as an orange solid from the reaction of 4-(salicylaldimine)antipyrine, with mixed cobalt(II) acetate and nickel(II) acetate in ethanol. The complex was characterized by Frustrated Total Internal Reflection (FTIR), UltraViolet Visible spectroscopy (UV-Vis), X-ray single crystal diffraction, and by elemental analysis. The complex is composed of two symmetry independent cationic units, A and B. The two units are essentially isostructural; nevertheless, small differences exist between them. The units contain four metal atoms, arranged at the corners of a distorted cubane-like core alternately with phenoxy oxygen of the Schiff base. The overall eight corners occupied by metal ions in the asymmetric unit are shared between cobalt and nickel in a 5.33:2.67 ratio. Each metal divalent cation binds three coordinated sites from the corresponding tridentate Schiff base ligand, the fourth one is bound by the acetate oxygen, the fifth and the sixth donor sites come from the phenolate oxygens of other Schiff base ligands. Intermolecular hydrogen bonds join the complexes to the water molecules present in the crystal packing. The magnetic characterization was carried out for this new complex and for its isostructural counterpart containing only cobalt ions. The magnetic measurements for the cobalt(II)/nickel(II) mixed compound indicate either antiferromagnetic interactions among the two cubanes or an anisotropic contribution, whereas a ferromagnetic interaction is observed within the cubane, for both the complexes, as expected by geometrical considerations. A comparison between the magnetic properties of the pure cobalt(II) derivative and similar systems discussed in literature, is presented.
The labile water molecules in the diplatinum(III) complex 2(µ-04 )4( 20)21 2" are sequentially replaced by halide, amine, thioether, and thiolato ligands. The products can be identified by chromophore shifts in the intense da -» da* transitions. These binuclear complexes Pt2(u-P04H)4L22" and 2(µ-04 )4 24" (L = uncharged ligand, X = anionic ligand) show a pseudoquintet (1:8:18:8:1) pattern in the 31P NMR spectrum. The X-ray structure of (Ph4As)2[Pt2(M-P04H)4(S(CH2)4)2]'2H3P04 shows the crystals to be triclinic with space group Pi and Z = 1. The unit cell dimensions are as follows: a = 10.584 (1) Á; b = 11.373(1) A; c = 15.138 (2) A; a = 77.23 (1)°; ß = 70.72 (1)°; 7 = 75.23 (1)°; V= 1644.4 (4) A3. The Pt-Pt distance is 2.525 (1) A, and the Pt-S distances are 2.462 (1) A. All the nonlinear angles about platinum are close to 90°.
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