- Reversible capture of small molecules on bimetallaborane clusters: Synthesis, structural characterization, and photophysical aspects
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Metallaborane compounds containing two adjacent metal atoms, [(PMe 2Ph)4MM′B10H10] (where MM′ = Pt2, 1; PtPd, 7; Pd2, 8), have been synthesized, and their propensity to sequester O2, CO, and SO 2 and to then release them under pulsed and continuous irradiation are described. Only [(PMe2Ph)4Pt2B 10H10], 1, undergoes reversible binding of O2 to form [(PMe2Ph)4(O2)Pt2B 10H10] 3, but solutions of 1, 7, and 8 all quantitatively take up CO across their metal-metal vectors to form [(PMe2Ph) 4(CO)Pt2B10H10] 4, [(PMe 2Ph)4(CO)PtPdB10H10] 10, and [(PMe2Ph)4(CO)Pd2B10H10] 11, respectively. Crystallographically determined interatomic M-M distances and infrared CO stretching frequencies show that the CO molecule is bound progressively more weakly in the sequence {PtPt} > {PtPd} > {PdPd}. Similarly, SO2 forms [(PMe2Ph)4(SO 2)Pt2B10H10] 5, [(PMe 2Ph)4(SO2)PtPdB10H10] 12, and [(PMe2Ph)4(SO2)Pd2B 10H10] 13 with progressively weaker binding of the SO 2 molecule. The uptake and release of gas molecules are accompanied by changes in their absorption spectra. Nanosecond transient absorption spectroscopy clearly shows that the O2 and CO molecules are liberated from the bimetallic binding site with high quantum yields of about 0.6. For 3, in addition to dioxygen release in the triplet ground state, singlet oxygen O2(1Δg) was also detected with a quantum yield 2 and CO molecules, from 3 and 4 respectively, is an ultrafast process taking place on a time scale of tens of picoseconds. For SO2, the release is even faster (2 and Pd 2 adducts, 5 and 13, the release of SO2 is significantly slower (>1 ns). All these compounds may have potential to serve as light-triggered local and instantaneous sources of the studied gases.
- Bould, Jonathan,Base, Tomas,Londesborough, Michael G. S.,Oro, Luis A.,MacIas, Ramon,Kennedy, John D.,Kubat, Pavel,Fuciman, Marcel,Polivka, Tomas,Lang, Kamil
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p. 7511 - 7523
(2011/10/03)
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- Ligand dependence of π-complex character in disilene-palladium complexes
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The synthesis and structures of new 16-electron disilene palladium complexes with 2,6-dimethylphenyl isocyanide and phenyldimethylphosphine ligands [L1L2Pd((t-BuMe2Si)2SiSi(SiMe 2Bu-t)2), where L1 = L2 = PhMe 2P; L1 = (cyclohexyl)3P, L2 = 2,6-dimethylphenyl isocyanide; L1 = L2 = 2,6-dimethylphenyl isocyanide] are described. Comparison of the X-ray structural parameters around the disilene moiety among these complexes and related bis(trimethylphosphine)(disilene)palladium and 14-electron (tricyclohexylphosphine)(disilene)palladium revealed that the π-complex character is sensitive to the residual ligands and increases with decreasing the strength of σ-donation from the ligands. The Royal Society of Chemistry 2006.
- Iwamoto, Takeaki,Sekiguchi, Yumiko,Yoshida, Naoki,Kabuto, Chizuko,Kira, Mitsuo
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p. 177 - 182
(2007/10/03)
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- Synthesis of heterobimetallic bis(diphenylphosphino)acetylene-bridged palladium-platinum complexes. Crystal and molecular structure of [PdPtCl4(Ph2PC≡CPPh2) 2]·2CHCl3
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Reaction of [(PMe2Ph)PdCl(μ-Cl)2PtCl(PMe2Ph)] (I) with 1,2-bis(diphenylphosphino)acetylene yields the heterobimetallic complex [Cl2Pd(Ph2PC≡CPPh2)2PtCl 2] (II). Solution studies using 31P and 195Pt NMR spectra reveal that II exists in an equilibrium of the type 2[Cl2Pd(Ph2PC≡CPPh2)2PtCl 2] ? [Cl2Pd(Ph2PC≡CPPh2)2PdCl 2] + [Cl2Pt(Ph2PC≡CPPh2)2PtCl 2]. Crystals of II [as the bis(chloroform) solvate] are monoclinic, space group P21/n with two formula units in a cell of dimensions a = 14.415 (3) A?, b = 12.149 (3) A?, c = 15.949 (3) A?, and β= 91.33 (2)°. The bimetallic complex lies about a crystallographic inversion center, and the Pd and Pt atoms are mutually disordered. The structure was solved by the heavy-atom method and refined by full-matrix least-squares calculations with anisotropic thermal parameters; R = 0.033 and Rw = (ΣwΔ2/ΣwF02)1/2 = 0.044 for 2407 observed reflections. The unique metal atom has slightly distorted square-planar geometry with mean M-Cl = 2.344 (2) A and mean M-P = 2.244 (2) A?. The strained 10-membered PtPdP4C4 ring system is nonplanar; there is significant bowing of the P-C≡C-P moiety [mean P-C ≡C = 172.2 (3)°] and enlargement of the M-P-C(acetylene) angles from tetrahedral [mean value 121.3 (2)°].
- Clark, Howard C.,Ferguson, George,Kapoor, Pramesh N.,Parvez, Masood
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p. 3924 - 3928
(2008/10/08)
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- CATIONIC η5-CYCLOPENTADIENYLPALLADIUM(II) COMPLEXES. COMPOUNDS OF TYPE 5-C5H5)L2>PF6 CONTAINING . TERTIARY PHOSPHINES, ARSINES, AND STIBINES. CRYSTAL AND MOLECULAR STRUCTURE OF η5-CYCLOPENTADIENYLBIS(TRIPHENYLSTIBINE)PALLADIUM(II) HEXAFLUOROPHOSPHATE-DICHLOROMETHANE (1/1)
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The complexes 5-C5H5)L2>PF6 have been prepared in high yield from the appropriate complexes and cyclopentadiene in Me2CO in the presence of AgPF6, or with AgNO3 followed by metathesis with NH4PF6.The brighly coloured compounds condudt as uni-univalent electrolytes in Me2CO and CH2Cl2 and have spectroscopic properties consistent with η5 co-ordination of the cyclopentadienyl moiety in solution.The molecular structure of 5-C5H5)(SbPh3)2>PF6*CH2Cl2 has been determined by a single crystal X-ray analysis.The crystals are monoclinic, space group P21/c with a=12.506(6), b=19.002(7), c=18.575(5) Angstoem, β=106.53(3) deg, and Z=4.The structure was solved by heavy-atom methods at 295(1) K and refined by least-squares methods to R=0.051 for 4383 observed reflections.The arrangement of two antimony atoms and the centre of the cyclopentadienyl ring about the palladium atom is approximately trigonal.The co-ordinated cyclopentadienyl moiety shows no significant deviations from planarity.
- Roberts, Nicholas K.,Skelton, Brian W.,White, Allan H.,Wild, Stanley, Bruce
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p. 2093 - 2098
(2007/10/02)
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