Synthesis and structural characterization of ferrocene phosphines modified with polar pendants and their palladium(II) complexes. Part I: N-aminocarbonyl and N-acyl phosphinoferrocene carboxamides
Abstract
Acylation of 1'-(diphenylphosphino)-1-(aminocarbonyl)ferrocene, Ph(2)PfcCONH(2) (1; fc = ferrocene-1,1'-diyl), afforded a series of acyl-ureas including Ph(2)PfcCONHCONHEt (1a), Ph(2)PfcCONHCONHPh (1b), and Ph(2)PfcCONHCONMe(2) (1c) as well as the acetyl derivative Ph(2)PfcCONHAc (1d). Compounds 1a-d were converted to the corresponding phosphine oxides (2a-d) and further examined as ligands in Pd(II) complexes.
The reactions of 1a-d with PdCl2(cod)] (cod = cycloocta-1,5-diene) at a 2:1 ligand-to-metal ratio gave the bis(phosphine) complexes [PdCl2(L-κP)(2)] (3a-d; L = 1a-d), whereas the reactions with [Pd(L-NC)Cl](2) (L-NC = [2-(dimethylamino-κN)methyl]phenyl-κC-1) produced the bridge-cleavage products, [PdCl(L-NC)(L-κP)] (4a-d). Removal of the Pd-bound halide from 4a-d with Ag[SbF6] furnished the corresponding cationic bis-chelate complexes [Pd(L-NC)(L-κ(2)O,P)][SbF6] (5a-d).
All compounds were characterized by NMR and IR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. The crystal structures of la, 2a-c, 3a.2CHCl(3), 3b.2CHCl(3), 3d.2CHCl(3), 4a-3CHCl(3), 4b.2.5CHCl(3), 5a.CHCl3, 5b.2CH2Cl(2), and 5d were determined by single-crystal X-ray diffraction analysis, which revealed that the hydrogen-bonded arrays formed in the crystals of free ligands are often preserved in the structures of their complexes.