Coordination chemistry of 1,1′-bis(2-pyridyl)ferrocene in palladium(II) and platinum(II) complexes and reaction of (BPF)Pd(Me)Cl with CO. X-ray structure of (1,1′-bis(2-pyridyl)ferrocene)Pd(Me)Cl and (1,1′-bis(2-pyridyl)ferrocene)[PtCl 2(CH 2  CH 2)] 2

Abstract

The coordination chemistry of the ligand 1,1′-bis(2-pyridyl)ferrocene (BPF) towards palladium and platinum has been studied. The very stable complexes (BPF)Pd(Me)Cl and BPF[PtCl 2(CH 2  CH 2)] 2 have been synthesized from (COD)Pd(Me)Cl and Zeise's salt respectively and characterized by 1H-, 13C-NMR, elemental analysis and single crystal X-ray determination. The crystals of (BPF)Pd(Me)Cl crystallize in he monoclinic space group C2 c (No.15) with a = 17.4681(9), b = 9.1112(6), c = 27.598(2) A ̊ , β= 92926(5)° V = 4360.3(5) A ̊ 3, Z = 8 . The structure refinement converged to R 1 = 0.042 for 3541 F 0 > 4 σ( F 0) and wR 2 = 0.084 for all 4982 unique reflections. The X-ray structure shows a square planar palladium complex with the ligand coordinated in a bidentate way with a relatively large bite angle of 84.48(13)°. The crystals of BPF[PtCl 2(CH 2  CH 2)] 2 have the space group P2 1 n with a = 13.8584(9), b = 13.128(3), c = 14.807(1) A ̊ and β = 90.13(1)°, V = 2693.9(7) A ̊ 3, Z = 4 . The structure refinement converged to R = 0.043 for 4310 observed reflections. This structure contains two PtCl 2(CH 2  CH 2) fragments bridged by one BPF ligand. A fast CO insertion occurs into the palladium-methyl bond of the complex (BPF)Pd(Me)Cl. When the product of this reaction, (BPF)Pd(C(O)Me)Cl, is kept under an atmosphere of 13CO, low temperature NMR and IR measurements show the presence of four complexes, which are (BPF)Pd(C(O)Me)Cl and probably (BPF)Pd(C(O)Me)(CO)Cl, cis- and trans-Pd 2(CO) 2(C(O)Me) 2Cl 2. Both the complexes (BPF)Pd(Me)Cl and (BPF)Pd(C(O)Me)Cl show a fluxional behaviour of the coordinated PBF ligand in solution on the NMR time scale, which involves the interconversion of two enantiomers of the complexes and the exchange of the two pyridyl groups of the ligand. BPF(PtCl 2(CH 2  CH 2)] 2, in which the ethylene is tightly coordinated to the metal centre, reacts with an additional BPF ligand to give the four-coordinated complex (BPF)PtCl 2(CH 2  CH 2).