3H-1,3-Azaphospholo[4,5-b]pyridines - novel heterocyclic P,N-bridging or hybrid ligands: synthesis and first d(8)-transition metal complexes

作者：Adam Mohamed Shaker S; Kindermann Markus K; Jones Peter G; Heinicke Joachim W

来源：Dalton Transactions, 2016, 45(5): 2261-2272.

DOI：10.1039/c5dt04073f

The first 3H-1,3-azaphospholo-pyridines 2a-c were synthesized as racemic mixtures in modest to medium yield by the reaction of N-(2-chloropyrid-3-yl)-trimethylacetimidoyl chloride 1 with RPLi2 (R = Ph, n-Bu, i-Bu), generated from RPH2 and BuLi in THF at -70 degrees C, and studied with respect to their suitability as ligands (L) in transition metal complexes. Reactions of 2a with group 6 metal(0) pentacarbonyls led to P-coordinated LM(CO)(5) complexes 3a-5a (Cr, Mo, W) and the reaction of 2c with (norbornadiene)Mo(CO)(4) surprisingly to 4c. [Rh(1,5-COD)Cl](2) and 2a,b, in metal/ligand ratio 1 : 1, furnished LRh(1,5-COD)Cl complexes 6a,b with P-coordination, 6b accompanied by a minor contamination by the bis-coordinated L[Rh(COD)Cl](2) complex 7b. Reactions of 2a,b with [(allyl)PdCl](2) proceeded in THF with dismutation of N-coordinated (allyl)PdCl and formed with 2a a labile crude product [(2a){(allyl)PdCl}(1.2)(PdCl2)(0.8)]center dot C4H8O, with the composition close to L[Pd(allyl)Cl]PdCl2 THF (8a center dot THF), which converted during crystallization to 9a, whereas 2b directly formed the N,N'-PdCl2-bridged bis[LPd(allyl)chloride] complex 9b. Conversion of 2b with equimolar amounts of Pd(CH3CN)(2)Cl-2 in THF, or Na2PdCl4 in methanol, gave rise to the dimeric P,N-bridging complex 10b. Crystal structure analyses of 6a (rac), 9b center dot 2CDCl(3) (meso), 10b center dot 4.5THF and 10b center dot 2D(6)-acetone (rac) provided detailed structural information. 10b, but more efficiently complexes formed in situ from 2a, b and Pd-2(DBA)(3) or Pd(OAc)(2), catalysed the arylamination of 2-bromopyridine with 2,4,6-trimethylaniline.

• 出版日期2016