The half-lantern compound [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)]·Me(2)CO (1) was obtained by reaction of equimolar amounts of potassium 2-mercaptobenzothiazolate (KC(7)H(4)NS(2)) and [Pt(bzq)(NCMe)(2)]ClO(4). The Pt(II)···Pt(II) separation in the neutral complex [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)] is 2.910 (2) Å, this being among the shortest observed in half-lantern divalent platinum complexes. Within the complex, the benzo[h]quinoline (bzq) groups lie in close proximity with most C···C distances being between 3.3 and 3.7 Å, which is indicative of significant π-π interactions. The reaction of 1 with halogens X(2) (X(2) = Cl(2), Br(2), or I(2)) proceeds with a two-electron oxidation to give the corresponding dihalodiplatinum(III) complexes [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)X}(2)] (X = Cl 2, Br 3, I 4). Their X-ray structures confirm the retention of the half-lantern structure and the coordination mode of the bzq and the bridging ligand μ-C(7)H(4)NS(2)-κN,S. The Pt-Pt distances (Pt-Pt = 2.6420(3) Å 2, 2.6435(4) Å 3, 2.6690(3) Å 4) are shorter than that in 1 because of the Pt-Pt bond formation. Time dependent-density functional theory (TD-DFT) studies performed on 1 show a formal bond order of 0 between the metal atoms, with the 6p(z) contribution diminishing the antibonding character of the highest occupied molecular orbital (HOMO) and being responsible for an attractive intermetallic interaction. A shortening of the Pt-Pt distance from 2.959 Å in the ground state S(0) to 2.760 Å in the optimized first excited state (T(1)) is consistent with an increase in the Pt-Pt bond order to 0.5. In agreement with TD-DFT calculations, the intense, structureless, red emission of 1 in the solid state and in solution can be mainly attributed to triplet metal-metal-to-ligand charge transfer ((3)MMLCT) [dσ*(Pt-Pt) → π*(bzq)] excited states. The high quantum yields of this emission measured in toluene (44%) and solid state (62%) at room temperature indicate that 1 is a very efficient and stable (3)MMLCT emitter, even in solution. The high luminescence quantum yield of its red emission, added to its neutral character and the thermal stability of 1, make it a potential compound to be incorporated as phosphorescent dopant in multilayer organic light-emitting devices (OLEDs).
Soils in ice-free areas of Livingston Island have been forming since the last deglaciation in a maritime warmer climate that is more humid than in interior Antarctica. A soil survey was carried out on Byers and Hurd peninsulas to characterize the soils and investigate the processes. Soils were sampled on two different substrates, mudstones and volcanic rocks in Byers Peninsula and greywackes in Hurd Peninsula. Sampling sites were located on raised beaches, platforms, and on volcanic outcrops across an altitudinal range from few m to 150 m a.s.l. The pH, electrical conductivity, carbonates and organic matter showed similar patterns in each geomorphic unit but their values differed between bedrocks. The sand, silt and clay contents differed greatly in the soils on mudstones and volcanic rocks. The elemental composition was closely related to mineralogy of parent materials. Mg, K, Zn, Mn, and Fe were similar in the soils on all bedrocks. The Al content was highest on the volcanic rocks. The largest difference in the Ca content was between the soils on greywackes and mudstones. The Na, Pb, and Ba contents in soils on the mudstones differed greatly from the rest of bedrocks. Geochemical and mineralogical characteristics suggest that the main process involved in soil development was the mechanical disintegration of bedrock although there was also some leaching. Cryogenic processes play a key role in soil development but chemical weathering processes were also involved in soil evolution although limited in extent due to the restriction of water circulation to summer.
The synthesis of the trinuclear phosphido complexes [NBu 4 ] 2 [(C 6 F 5 ) 2 M(µ-PPh 2 ) 2 M′(µ-PPh 2 ) 2 M′′(C 6 F 5 ) 2 ] (M, M′, M′′ ) Pd(II), Pt(II), 1-5) is described. A study of the electrochemical behavior of these complexes is reported. The chemical oxidation of the homonuclear platinum derivative involving two electrons yields the complex [(C 6 F 5 ) 2 Pt(µ-PPh 2 ) 2 Pt(µ-PPh 2 ) 2 Pt(C 6 F 5 ) 2 ] (6), which contains Pt in average formal oxidation state 2.67. The structure of the complexes has been established by spectroscopic means, and X-ray diffraction studies have been carried out on 1 and 6. Quantum chemical calculations at the B3LYP level of theory, using the LANL2DZ basis set, provide a satisfactory description of the structural, bonding, energetic, and electronic properties of these phosphido-bridged trinuclear M 3 (II) compounds modeled as [(CF 3 ) 2 M(µ-PH 2 ) 2 M′(µ-PH 2 ) 2 M′′(CF 3 ) 2 ] 2-(M, M′, M′′ ) Pd(II), Pt(II), 1M-5M) and the oxidation product [Pt 3 (µ-PH 2 ) 4 (CF 3 ) 4 ] (6M).a The symmetry transformation used to generate equivalent P(2′) atom is -x, -y, -z.
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