Selective Formation of Rhodium Diacyl or Acyl Hydrido Hemiaminal Complexes in the Reaction of o-(Diphenylphosphino)benzaldehyde with Rhodium 2-Aminopyridine or 2-(Aminomethyl)pyridine Compounds
详细信息 查看全文
- 作者：Marí ; a A. Garralda ; Ricardo Herná ; ndez ; Lourdes Ibarlucea ; Elena Pinilla ; M. Rosario Torres ; Malkoa Zarandona
- 刊名：Organometallics
- 出版年：2007
- 出版时间：October 22, 2007
- 年：2007
- 卷：26
- 期：22
- 页码：5369 - 5376
- 全文大小：172K
- 年卷期：v.26,no.22(October 22, 2007)
- ISSN：1520-6041
文摘
[RhCl(COD)]2 (COD = 1,5-cyclooctadiene) reacts with PPh2(o-C6H4CHO) in the presence of2-aminopyridine (apy) to give the diacyl [RhCl(PPh2(o-C6H4CO))2(apy)] (1) with evolution of hydrogen.1 is a mixture of two isomers, 1a with trans P atoms and cis acyl groups and 1b with cis P atoms andtrans acyl groups. In solution fast exchange between phosphorus atoms of the two isomers and alsodecreasing of the 1a:1b ratio occur on raising the temperature. This behavior can be due to intramolecularopening of the acyl-phosphine chelate. Complex 1 reacts with bidentate N-donor ligands to afford cationicdiacyl derivatives [Rh(PPh2(o-C6H4CO))2(NN)]+ (NN = 2,2'-bipyridine, 2; glyoxaldihydrazone, 3; 1,2-phenylenediamine, 4; ethylenediamine, 5; 2-(aminomethyl)pyridine (ampy), 6, 7; 8-aminoquinoline (aqui),8) with high stereoselectivity depending on the N-donor ligand employed. Diimine ligands give onlycomplexes with trans phosphorus atoms (2, 3), diamine ligands give only derivatives containing cisphosphorus atoms (4, 5), and ligands containing amino-imine functionalities afford both types of isomers.Ampy allows the isolation of both complexes 6 and 7. Complex 6, with trans phosphorus atoms, is thekinetic product of the reaction, and 7, with cis phosphorus atoms, is the most stable thermodynamicisomer. The rate of the isomerization reaction of 6 into 7 depends on the solvent and also on the counterion,suggesting that this reaction may be assisted by ion-pair formation via hydrogen bonding. The reactionof [RhCl(COD)]2 with PPh2(o-C6H4CHO) in the presence of ampy or the reaction of the phosphine-aldehyde complex [RhClH(PPh2(o-C6H4CO))(2-PPh2(o-C6H4CHO))] (10) with ampy leads to [RhH(PPh2(o-C6H4CO))(PNN)]Cl (9) (PNN = 3-PPh2(o-C6H4CHOH-NH-CH2-C5H4N)), containing a hemiaminal group (>CH(OH)NH-) formed by the reaction of the aldehyde with the amino group. Complex10 reacts with aqui to afford [RhH(PPh2(o-C6H4CO))(PPh2(o-C6H4CH=N-C9H6N))]+ (11), containing aPNN ligand with an imine functionality. The hemiaminal stability seems to be favored by the presenceof a single sp3 carbon atom in 9. All the complexes were fully characterized spectroscopically. Single-crystal X-ray diffraction analysis was performed on 1a and 7.