Unusual coordination of tetraphenylborate to silver(I): synthesis and X-ray crystal structure of the complex N,N'-bis[3-(2-nitrophenyl)allylidene]ethane-1,2 diamine(tetraphenylborato)silver(I)

Abstract

[Ag(nca 2 en)(BPh 4 )], foi sintetizado e caracterizado por análise elementar e por espectroscopias de RMN de 1 H, de absorção no infravermelho e UV-vis. Sua estrutura cristalina e molecular foi determinada por difratometria de raios X (monocristal). O centro de prata(I) no complexo está em um ambiente tetraédrico distorcido e faz ligações covalentes com os dois átomos de nitrogênio da base de Schiff e com dois átomos de carbono do tetrafenilborato. No complexo, o tetrafenilborato apresenta um comportamento não-usual, agindo como um ligante bidentado. The complex N,N'-bis[3-(2-nitrophenyl)allylidene]ethane-1,2-diamine(tetraphenylborato)silver(I), [Ag(nca 2 en)(BPh 4 )], has been synthesized and characterized by CHN analyses and 1 H-NMR, IR and UV-vis spectroscopies. Its crystal and molecular structure was determined by X-ray diffractometry from single-crystal data. The coordination geometry about silver(I) is best described as a distorted tetrahedron. The Ag center is covalently bonded to two N atoms of the Schiff base and two C atoms of tetraphenylborate. In the complex, tetraphenylborate shows an unusual behavior and acts as a bidentate ligand.

Transmetalation of Unsaturated Carbon Nucleophiles from Boron-Containing Species to the Mid to Late d-Block Metals of Relevance to Catalytic C−X Coupling Reactions (X = C, F, N, O, Pb, S, Se, Te)

“…In general, the three ligands for which this scenario can occur are boroxides ( O -bonded, deprotonated organoborinic or organoboronic acid derivatives), O -bonded hydroxyborates (ligands of general type HOBAr 3 − ), and tetraorganylborates ( C -bonded, where most frequently all four organic groups are aryl groups). In the case of tetraorganylborates, the π-face of the arene ring serves as the ligand with hapticity η x , where x = 1, 2, 3, 4, 5, or 6. − Typically, neither tetraorganylborates nor hydroxyborates are strongly binding ligands, being readily displaced by ligands that in and of themselves are not strongly binding. For example, in one mechanistic study of the Suzuki−Miyaura cross-coupling reaction, Crociani and co-workers detected an arylborate-ligated Pd complex ( 205 ) as an intermediate that was stable enough to isolate .…”

Dissecting Transmetalation Reactions at the Molecular Level: Phenyl Transfer in Metal Borate Complexes

“…Besides the evidence of the occurrence of transmetalation from boron to silver from these synthetic studies, several stages of this reaction have been intercepted and characterized structurally, thus making the boron/silver system one of the best studied models for transmetalation . A survey of the Cambridge Crystal Structure database on products of the reactions of silver salts with tetraaryl borates reveals various structures from the transmetalation continuum, including the solvent-separated ion pair (Scheme F), the so-called arrested transmetalation adduct formed by coordination of silver to the aromatic rings (Scheme G) and the final organosilver product of transmetalation (Scheme H) …”

Synthesis, characterization and crystal structures of the bidentate Schiff baseN,N′-bis(2-nitrocinnamaldehyde)ethylenediamine and its complex with CuNCS and triphenylphosphane

“…In this paper, we report the synthesis, spectroscopic characterization and crystallographic structural study of the Schiff base N,N 0 -bis-(trans-2-nitrocinnamaldehyde)ethylenediamine (Nca 2 en), (1), and its Cu I complex, (2), containing also triphenylphosphane and isothiocyanate as ligands (see Scheme 1), and compare this complex with others containing the same ligand and its analogue without nitro groups. Although the structures of 11 complexes of (1) as a ligand with cobalt, nickel, copper, zinc and silver have been reported (Kirchner et al, 1987;Dehghanpour, Mahmoudi, Sepaveh & Ng, 2006;Dehghanpour & Mahmoudi, 2007;Habibi, Montazerozohori et al, 2007;Dehghanpour, Mahmoudi & Haghighatseresht, 2006;Dehghanpour, Kempe et al, 2006;Habibi, Lalegani et al, 2007a,b,c;Dehghanpour et al, 2008), the crystal structure of (1) itself has been obtained now for the first time (with the aid of synchrotron radiation because of the very small crystal size and twinning). The analogous Schiff base without nitro groups, N,N 0 -bis(trans-cinnamaldehyde)ethylenediamine, (3), has previously been crystallographically characterized (Khalaji & Weil, 2007), as have 18 of its complexes with cobalt, nickel, copper, zinc and silver (Meghdadi et al, 2002;Kickelbick et al, 2002Kickelbick et al, , 2003Khalaji, Aoki & Amirnasr, 2007;Amirnasr et al, 2003Amirnasr et al, , 2006Khalaji et al, 2006;Khalaji, Amirnasr & Schenk, 2007;Cai et al, 2008).…”