Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
2.
J Am Chem Soc ; 131(25): 8989-99, 2009 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-19480461

RESUMO

Room temperature photolysis of aminoborylene complexes, [(CO)(5)M=B=N(SiMe(3))(2)] (1: M = Cr, 2: Mo) in the presence of a series of alkynes and diynes, 1,2-bis(4-methoxyphenyl)ethyne, 1,2-bis(4-(trifluoromethyl)phenyl)ethyne, 1,4-diphenylbuta-1,3-diyne, 1,4-bis(4-methoxyphenyl)buta-1,3-diyne, 1,4-bis(trimethylsilylethynyl)benzene and 2,5-bis(4-N,N-dimethylaminophenylethynyl)thiophene led to the isolation of novel mono and bis-bis-(trimethylsilyl)aminoborirenes in high yields, that is [(RC=CR)(mu-BN(SiMe(3))(2)], (3: R = C(6)H(4)-4-OMe and 4: R = C(6)H(4)-4-CF(3)); [{(mu-BN(SiMe(3))(2)(RC=C-)}(2)], (5: R = C(6)H(5) and 6: R = C(6)H(4)-4-OMe); [1,4-bis-{(mu-BN(SiMe(3))(2)(SiMe(3)C=C)}benzene], 7 and [2,5-bis-{(mu-BN(SiMe(3))(2) ((C(6)H(4)NMe(2))C=C)}-thiophene], 8. All borirenes were isolated as light yellow, air and moisture sensitive solids. The new borirenes have been characterized in solution by (1)H, (11)B, (13)C NMR spectroscopy and elemental analysis and the structural types were unequivocally established by crystallographic analysis of compounds 6 and 7. DFT calculations were performed to evaluate the extent of pi-conjugation between the electrons of the carbon backbone and the empty p(z) orbital of the boron atom, and TD-DFT calculations were carried out to examine the nature of the electronic transitions.

3.
Chem Commun (Camb) ; (4): 497-8, 2008 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-18188480

RESUMO

The first catalytic application of the Group VI metal borylene complexes [(CO)(5)M[double bond]BN(SiMe(3))(2)] involves the demercuration reaction of bis(alkynyl)mercurials, [Hg(C[triple bond]CR)(2)], with formation of a series of buta-1,3-diynes.

5.
Chemistry ; 13(25): 7171-6, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17594710

RESUMO

A series of platinum(II) boryl complexes of general formula trans-[(Cy(3)P)2Pt(Br)(BX2)], including the rare dibromoboryl species trans-[(Cy(3)P)2Pt(Br)(BBr2)], were synthesized by oxidative addition of the B-Br bond of a number of bromoboranes to [Pt(PCy3)2]. X-ray diffraction studies were performed on several such compounds. Comparison of the Pt--Br bond lengths allowed an empirical assessment of the trans-influence of different boryl ligands. A trans-influence scale was thus deduced and the results were compared with those previously computed for compounds of the type trans-[(Me(3)P)2Pt(Cl)(BX2)].

6.
Chemistry ; 13(17): 4770-81, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17366491

RESUMO

Transition-metal-borylene complexes of the type [(OC)(5)M=BR] {M=Cr, Mo, W; R=N(SiMe(3))(2), 1a-3a, Si(SiMe(3))(3), 4a} and [(OC)(4)Fe=B=N(SiMe(3))(2)] (8) were prepared by salt elimination reactions. Synthesis of the latter complex was accompanied by the formation of substantial amounts of an unusual dinuclear iron complex [Fe(2){mu-C(2)O(2)(BN(SiMe(3))(2))}(2)(CO)(6)] (9). The aminoborylene complexes of Group 6 metals were converted to trans-[(Cy(3)P)(CO)(4)M=B=N(SiMe(3))(2)] (5a-7a) by irradiation in the presence of PCy(3). Structural and spectroscopic parameters were discussed with respect to the trans-effect of the borylene ligand and the degree of M-B d(pi)-p(pi)-backbonding. Computational studies were performed on Group 6-borylene complexes. The population and topological analyses as well as the molecular orbital composition are consistent with the presence of both sigma-and pi-type interactions. There are, however, indications that the d(pi)-p(pi)-backbonding in the silylborylene complex is significantly more pronounced than in the aminoborylene complexes.

7.
Angew Chem Int Ed Engl ; 45(32): 5254-74, 2006 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-16826611

RESUMO

Since the publication of the last review in 1998, the transition-metal chemistry of boron has continued to raise unceasing interest. Boryl complexes, representing the most extensive subclass, have remained a focus of intense research, particularly for their implication in the metal-mediated functionalization of organic substrates. Absolute novelties such as borane complexes and terminal borylene complexes have been structurally authenticated. Upon further elaboration of these compounds, the known coordination modes of boron-based ligands have grown considerably. Combined structural and theoretical investigations have contributed to elucidate the fundamental electronic characteristics of the transition-metal-boron bond and are leading to applications of these compounds. The most useful synthetic strategies for the generation of transition-metal-boron bonds are highlighted here, and the most recent and intriguing compounds that have been reported are outlined and discussed.

13.
J Am Chem Soc ; 127(5): 1386-7, 2005 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-15686366

RESUMO

Heterodinuclear bridged borylene complexes are synthesized via oxidative addition of the B-Br bond of bromoboryl complex precursors to an electron-rich palladium species. The synthetic protocol grants access to the first compound featuring the reactive bromoborylene ligand.

15.
Chemistry ; 10(16): 3970-8, 2004 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-15317061

RESUMO

The late-transition-metal parent amido compound [Ir(Cp*)(PMe3)(Ph)(NH2)] (2) has been synthesized by deprotonation of the corresponding ammine complex [Ir(Cp*)(PMe3)(Ph)(NH3)][OTf] (6) with KN(SiMe3)2. An X-ray structure determination has ascertained its monomeric nature. Proton-transfer studies indicate that 2 can successfully deprotonate p-nitrophenylacetonitrile, aniline, and phenol. Crystallographic analysis has revealed that the ion pair [Ir(Cp*)(PMe3)(Ph)(NH3)][OPh] (8) exists as a hydrogen-bonded dimer in the solid state. Reactions of 2 with isocyanates and carbodiimides lead to overall insertion of the heterocumulenes into the N--H bond of the Ir-bonded amido group, demonstrating the ability of 2 to act as an efficient nucleophile. Intriguing reactivity is observed when amide 2 reacts with CO or 2,6-dimethylphenyl isocyanide. eta4-Tetramethylfulvene complexes [Ir(eta4-C5Me4CH2)(PMe3)(Ph)(L)] (L=CO (15), CNC6H3-2,6-(CH3)2 (16)) are formed in solution through displacement of the amido group by the incoming ligand followed by deprotonation of a methyl group on the Cp* ring and liberation of ammonia. Conclusive evidence for the presence of the Ir-bonded eta4-tetramethylfulvene moiety in the solid state has been provided by an X-ray diffraction study of complex 16.


Assuntos
Amidas/síntese química , Irídio/química , Compostos Organometálicos , Amidas/química , Cristalografia por Raios X , Ciclopentanos/química , Ligantes , Modelos Moleculares , Conformação Molecular , Compostos Organometálicos/síntese química , Compostos Organometálicos/química , Fosfinas/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA