Vinicius Caliman

Preparation and ligating properties of the first example of a 1,2,4-triphosphole, P3C2But2R [R = CH(SiMe3)2]: crystal and molecular structures of P3C2But2CH(SiMe3)2, trans-[PtCl2(PEt3){P3But2CH(SiMe3)2}]and[Fe2(CO)6{µ-P3C2But2CH(sime3)2}]

The first known triphosphole exhibits different modes of ligation to transition-metal centres.

Facile Graphene Oxide Preparation by Microwave-Assisted Acid Method

Few-layered graphene oxide (GO) was prepared using a fast and energy-saving method by microwave-assisted acid technique. The oxygenated groups existing on the GO surface were determined using UV-Vis, X-ray photoelectron and Fourier-transform infrared spectroscopies. An oxygenated group percentage of 30% in mass for the GO was observed by thermogravimetric analysis. The reduced few-layered graphene oxide (rGO) film annealed at 110 °C deposited onto a silicon/silica wafer showed expanded graphite-like structure with 0.70 nm between the rGO sheets, as determined by X-ray diffraction. This rGO film exhibited a relatively high electrical conductivity value of 7.36 × 102 S m-1 confirming the good restoration of the π-conjugated system. The prepared GO sample exhibited good stability in water from pH 4 to 12, as determined by its zeta potential, and contained 5 to 9 layers, as determined by atomic force microscopy (AFM) and transmission electron microscopy (TEM).

The first 2,3-dihydro-1H-(1,2,4) triphosphole

Abstract Protonation of the lithium triphospha-cyclopentenyl salt Li (P3C2But2RR′) (R=(Me3Si)2CH-, R′=Bun) with HCl affords the new 2,3-dihydro-1H-[1,2,4] triphosphole P3C2But2(H) (Bun)CH(SiMe3)2 which has been structurally characterised as its [W(CO)5] complex.

THE WIDE SYNTHETIC VERSATILITY OF FIVE MEMBERED RINGS CONTAINING PHOSPHORUS

The chemistry of cyclopentadiene rings has been widely studied. This review article deals with a similar chemistry of new compounds containing from 1 to 5 phosphorus atoms on the ring substituting the carbon atoms. The neutral rings containing one, two and three phosphorus atoms can be used as building blocks for the synthesis of new organic compounds containing phosphorus. These rings plus the anionic ones also show great potential as ligands in coordination chemistry. The aim of this article is to show how important this new area is and how diverse the chemistry related to a single type of ring can be.

Synthesis, Characterization and Theoretical Calculations of Novel Five Membered Rings Containing Phosphorus and Arsenic Atoms

The synthesis of two new arsadiphospholes of formula (AsP2C2But2 )CH(SiMe3)2, from 4-arsa-1,2-diphosphacyclopentadienyl and 2-arsa-1,4-diphosphacyclopentadienyl ring anions are reported together with their characterization by 31P NMR. Ab initio calculations at the MP2/6-31G(d) level of theory were carried out to investigate the energy barrier for pyramidal inversion about the pyramidal P and As atoms, relative stability and aromaticity character of all possible isomers in the gas phase. The thermodynamic isomers distribution is in agreement with the experimental results. The inversion barrier at the sp3 phosphorus compared to the inversion barrier found for the arsenic atom is low. This fact is directly related with the aromaticity of the rings and shows the preference of the side group for the phosphorus atom, which leads to a more aromatic ring structure. The aromaticity character found for three isomers containing a sp3-phosphorus is greater if compared with that of 1,2,4-triphosphole synthesized previously. The effects of bulky R substituents on the aromaticity and on the energy barrier for pyramidal inversion are also discussed.

Polímeros com condutividade iônica: desafios fundamentais e potencial tecnológico

Polimeros condutores ionicos ou eletrolitos polimericos constituidos por um sistema de sal dissolvido em uma matriz polimerica solida sao materiais que apresentam interesse cientifico e potencial tecnologico. A dissolucao de sais em uma matriz polimerica amorfa ou semicristalina solida leva a estudos sobre intrigantes aspectos estruturais, que podem ser abordados por tecnicas fisico-quimicas diversas tais como RMN, Raman e Espectroscopia de Vida Media de Positrons. Os estudos estruturais sao correlacionados com propriedades eletroquimicas visando a utilizacao desses materiais em dispositivos tais como baterias, supercapacitores e celulas solares. Grupos brasileiros tem gradativamente ampliado os estudos e aplicacoes de eletrolitos polimericos solidos.

Novel Organophosphorus Cage Compound Produced by an Unexpected Oxidative Coupling of 1,2,4-Triphosphole: Crystal and Molecular Structures of Two Isomers of Formula P6C4Bu t4 CHSiMe3

Li(P3C2But2) reage com BrCH(SiMe3)2, via adicao oxidativa, formando um novo composto organofosforado de formula molecular P6C4But4 CHSiMe3 (1). O composto 1 foi caracterizado espectroscopicamente e sua estrutura molecular determinada atraves de difracao de raios X de monocristais. Juntamente com 1, foi caracterizado outro composto (2) com a mesma formula molecular, mas apresentando uma estrutura completamente saturada.

Remarkable ‘edge’ ligation of a triphosphacyclopentenylring system. Synthesis, crystal and molecular structure of[Ni(η5-P3C2But2){η2-P3C2But2CH(SiMe3)2Me}]

In the nickel(II) complex [Ni(η 5 -P 3 C 2 Bu t 2 )(η 2 -P 3 C 2 Bu t 2 CH(SiMe 3 ) 2 Me}] the triphosphacyclopentenyl ring P 3 C 2 Bu t 2 CH(SiMe 3 ) 2 Me is unexpectedly coordinated to the metal exclusively via the two adjacent saturated ring phosphorus atoms, rather than via the 2-phosphaallyl fragment.

First syntheses, structural and theoretical studies ofη5-1,2,4-triphosphole metal tricarbonyl complexes of Cr, Moand W

Evidence for an η 5 -ligated 1,2,4-triphosphole ring system which exhibits some aromatic character is presented via the first syntheses, structural and theoretical studies of η 5 -1,2,4-triphosphole metal tricarbonyl complexes of zerovalent Cr, Mo and W.

Synthesis and coordination chemistry of 1,3,5-triphosphabicyclo[2.1.0]- pent-2-ene

Room temperature electrocyclisation of the 1,2,4-triphosphole P3C2But2CH(SiMe3)2 affords the new 1,3,5-triphosphabicyclo[2.1.0]pent-2-ene which undergoes a very rapid [1,3]-phosphorus migration which can be stopped by coordination of [W(CO)5]; the two isomeric phosphorus compounds react differently with [PtCl2(PEt3)]2, the latter via an insertion of the metal into the P–P bond and a chlorine migration reaction to afford trans-[PtCl(PEt3)P2C2- But2PClCH(SiMe3)2], the molecular structure of which has been determined by a single crystal X-ray diffraction study.