128389-47-9

The bis(chelate) complexes O)2>2 (3a-e) react with methylmagnesium chloride with a concomitant cleavage of two weak Pd-O bonds to give the methyl complexes trans-ClPd(PO)2(CH3) (4a-e) (PO: η1-P-coordinated; PO: η2-O,P-chelated; Scheme 1).Diffusion of pentane into the reaction mixture of 4a-e in the presence of the formed magnesium salts yields the cationic complexes trans-O)-(PO)> (6a, c).The reaction of 3a-e with benzylmagnesium chloride affords the cationic benzyl complexes cis-O)(PO)> (8a-e) inwhich only one Pd-O bond has been cleaved.In the presence of carbon monoxide 4a-e and 6a, c are transformed into the corresponding acyl complexes CH3C(O)Pd(PO)2Cl (5a-e) and O)(PO)> (7a, c).Whereas at 183 K variable-temperature 31P-NMR measurements of 6a, c, 7a, c indicate a non-rigid behavior of the two differently bound ether-phosphanes, the dynamic process is frozen out for 8a-e.By a line-shape analysis of the spectra the thermodynamic parameters ΔG(excit.), ΔH(excit.), and ΔS(excit.) are obtained.According to a crystal structure analysis 3d and 6c crystallize in the monoclinic space group P21/c with Z = 4.Key Words: Palladium complexes, alkyl- and acyl- / Ether phosphanes / Fluxional behavior

Cl2Pd(COD) (1) (COD = 1,5-cyclooctadiene) reacts with 1 equiv. of the (ether-phosphine) ligand Ph2P-D (2a-c) to give the dimeric complexes 2 (3a-c) (P-D = η1-P-coordinated).According to the field-desorption mass spectra which show only one peak for the monomeric moieties ClPd(Ph2P-D), 3a-c have a very weak Pd2Cl2 bridge. trans-Cl2Pd(Ph2P-D)2 (4a-c) is obtained either from 3a-c and 2a-c by cleaving the Pd2Cl2 bridge or from 1 and 2 equiv. of the ligands 2a-c. 4c crystallizes in the monoclinic spacegroup P21/c with Z = 2.AgClO4 selectively abstracts one Cl- ligand from 4a-c which results in the formation of the cationic complexes D)(Ph2P-D)PdCl>+ (5a-c) (PD = η2-D,P-coordinated) containing one chelated and one η1-P-bonded (ether-phosphine) ligand. 5a-c show fluxional behavior which is demonstrated by temperature-dependent 31P-NMR investigations.The coalescence points have been determined and are at 253 (5a), 303 (5b), and 283 K (5c).The activation enthalpies ΔGexcit. are estimated at 48, 58, and 54 kJ/mol.The abstraction of the second Cl- ligand from 5a-c succeeds only in the presence of AgSbF6 yielding the dicationic bis(chelate) complexes D)2Pd>2+ (6a-c).The latter are also obtained from 4a-c and AgSbF6.The hydrogenating properties of 3a-c and 4a-c toward 1-hexyne are investigated in comparison with trans-Cl2Pd(Ph2PCH2CH2CH3)2.