Carlos Díaz Valenzuela

Synthesis and spectroscopic properties of a new high molecular weight poly-spirophosphazene-oxypyridine copolymer and its complexes with W(CO)5 fragments

Abstract The polyspirophosphazene copolymer {[NP(O 2 C 12 H 8 )] 0.7 [NP(OC 5 H 4 N) 2 ] 0.3 } n ( 2 ); that carries pyridine side groups has been prepared from [NPCl 2 ] n , by reaction first with 2,2′-dihydroxybiphenyl and potassium carbonate in THF to give a solution of the partially substituted polymer {[NP(O 2 C 12 H 8 )] 0.7 [NPCl 2 ] 0.3 } n ( 1 ), followed by the reaction of the latter with 4-hydroxypyridine (HOC 5 H 4 N) also in the presence of potassium carbonate. The reaction of ( 2 ) with [W(HOMe)(CO) 5 ] in a CH 2 Cl 2 –MeOH mixture gave the polymeric complex {[NP(O 2 C 12 H 8 )] 0.7 [NP(OC 5 H 4 NW(CO) 5 ) 2 ] 0.3 } n ( 4 ), that, upon treatment with NCMe in THF produced derivatives with less metal carbonyl contents.

Synthesis and spectroscopic characterization of cyclic and polymeric phosphazenes bearing phosphine complexes

Abstract The reactions of the cyclic phosphazenes [N 3 P 3 Cl 6 ] and [N 3 P 3 (O 2 C 12 H 8 ) 2 Cl 2 ] (O 2 C 12 H 8 =2,2′-dioxybiphenyl) with the diphenylphosphine phenol complex {Mn(CO) 2 (η 5 -C 5 H 4 Me)[PPh 2 (C 6 H 4 OH)]} ( 1 ) and Cs 2 CO 3 in refluxing acetone gave, respectively the phosphazene–phosphine complexes {N 3 P 3 [OC 6 H 4 PPh 2 Mn(CO) 2 (η 5 -C 5 H 4 Me)] 6 } ( 2 ) and {N 3 P 3 (O 2 C 12 H 8 ) 2 [OC 6 H 4 PPh 2 Mn(CO) 2 (η 5 -C 5 H 4 Me)] 2 } ( 3 ), in good yields. The analogous reaction of the partially substituted clorophosphazene polymer {[NP(O 2 C 12 H 8 )] 0.6 [NPCl 2 ] 0.4 } n in THF gave the polymeric complex [{NP(O 2 C 12 H 8 )} 0.6 {NP[OC 6 H 4 PPh 2 Mn(CO) 2 (η 5 -C 5 H 4 Me)] 2 } 0.4 ·0.5[OC 4 H 8 ] n ( 4 ). Different spectroscopic data are provided for the new compounds that may be useful for the characterization of other more complex polymeric materials.

Solid state pathways to complex shape evolution and tunable porosity during metallic crystal growth.

Growing complex metallic crystals, supported high index facet nanocrystal composites and tunable porosity metals, and exploiting factors that influence shape and morphology is crucial in many exciting developments in chemistry, catalysis, biotechnology and nanoscience. Assembly, organization and ordered crystallization of nanostructures into complex shapes requires understanding of the building blocks and their association, and this relationship can define the many physical properties of crystals and their assemblies. Understanding crystal evolution pathways is required for controlled deposition onto surfaces. Here, complex metallic crystals on the nano- and microscale, carbon supported nanoparticles, and spinodal porous noble metals with defined inter-feature distances in 3D, are accomplished in the solid-state for Au, Ag, Pd, and Re. Bottom-up growth and positioning is possible through competitive coarsening of mobile nanoparticles and their site-specific crystallization in a nucleation-dewetted matrix. Shape evolution, density and growth mechanism of complex metallic crystals and porous metals can be imaged during growth.

THE MASS SPECTRAL FRAGMENTATION OF N,N-DITHIOBISAMINES AND THEIR CYCLIC ANALOGUES 3,6-DIALKYL-1,2,4,5,3,6-TETRATHIADIAZINES

Abstract The mass spectra of the series of compounds R2NSSNR2 where and N(CH2-C6H5)2 and of its cyclic analogues RN(S2)2NR where R-CH3, C6H11 and CH2-C6H5 are presented and discussed. The major fragmentation modes of these compounds involves the cleavage of the C-N, S-N and S-S bonds. The nature of the fragments containing sulfur atoms, arising from S-N and S-40 rupture, is dependent on the cyclic or acyclic structure of the compounds.

SYNTHESIS, SPECTROSCOPIC AND ELECTROCHEMICAL STUDY OF CATIONIC CICLOPENTADIENYLIRON(DIPHOSPHINE) COMPLEXES SUPPORTED ON A HIGH MOLECULAR WEIGHT PHOSPHAZENE POLYMER THROUGH NITRILE LIGANDS

The high molecular weight phosphazene random copolymer {[NP(OC6H5)2]0.94 [NP(OC6H5)(OC6H4CNFe(dppe)Cp)]0.06[PF6]0.06}n (1), that carries [Fe(dppe)Cp] cationic fragments coordinated to nitrile side groups, has been synthesized from the copolymer {[NP(OC6H5)2]0.94[NP(OC6H5)(OC6H4CN)]0.06}n and the complex [Fe(CH3CN)(dppe)Cp][PF6] by the complete elimination of the acetonitrile from the equilibrium mixture that they form in dichloromethane solution. The new polymer has been fully characterized by a detailed discussion of the IR and NMR data that may be also useful for the study of other polymeric complexes with similar metal fragments. The cyclic voltammogram of (1) showed an oxidation process that is chemically irreversible but, rather unexpectedly, electrochemically reversible. All the results were interpreted by comparison with the data obtained for the new cyclic model complexes {N3P3(OC6H4-R)5[OC6H4CNFe(dppe)Cp]}[PF6] R=H (2a), But (2b), (see chart 1) that were synthesized by a similar method using the nitrile phosphazene ligands [N3P3(OC6H4-R)5(OC6H4CN)]

ROLE OF THE LINKING OF METALLIC CENTERS TO MACROMOLECULAR AND OLIGOMERIC SYSTEMS IN THE PYROLYTIC PRODUCTS

ABSTRACT Pyrolysis of the mixtures: [NP(O 2 C 12 H 8 )] n // AuCl(PPh 2 ) system (I) [NP(O 2 C 12 H 8 )] 0.8 [NP(OC 6 H 4 CH 2 CN.{Ru]) 2 ] 0.15 NP(OC 6 H 5 )1OC 6 H 4 CH 2 CN.[Ru] 0 . 05 ] n // t BuSiMe 2 Cl system (II) and N 3 P 3 [NH(CH 2 ) 3 Si(OEt) 3 ] 6 // N 3 3 [OC 6 H 4 CH 2 CN. TiCp 2 Cl] 6 (PF 6 6 system (III) were studied in air and at 800 °C, and their products characterized. Nanostructured Au foams; RuO 2 and Ti(PO 3 ) 3 islands deposited on SiP 2 O 7 / P 4 O 7 matrix respectively were obtained. System (I) affords similar results to the pyrolysis of the polyphosphazene having the AuCl(PPh 2 ) coordinated to the polymeric chain which can be attributed to a probable coordination of the Au fragments to the polymer during the heating process. In the system (II) the no presence of metallic nanostructures containing Si was attributed to the absence of Si ultraestructures due to the no cross-linking of the precursor by volatilization of the silicon molecular compound. In the system (III) the ciclic trimer acts each one as template for the formation of mesostructured products remaining separated at the micro level.Keywords: Polyphosphazenes, organometallic metallic, nanostructure. e-mail: cdiaz@uchile.cl.