Ni(ii), Pd(ii) and Pt(ii) complexes of PNP and PSP tridentate amino–phosphine ligands

Abstract

The ligands D((CH₂)₂NHPiPr₂)₂ (D = NH 1, S 2) react with (dme)NiCl₂ or (PhCN)₂MCl₂ (M = Pd, Pt) to give complexes of the form [D((CH₂)₂NHPiPr₂)₂MX]X (X = Cl, I; M = Ni, Pd, Pt) which were converted to corresponding iodide derivatives by reaction with Me₃SiI. Reaction of 1 or 2 with (COD)PdMeCl affords facile routes to [κ³P,N,P-NH((CH₂)₂NHPiPr₂)₂PdMe]Cl (8a) and [κ³P,S,P-S((CH₂)₂NHPiPr₂)₂PdMe]Cl (9a) in high yields. An alternative synthetic approach involves oxidative addition of MeI to a M(0) precursor yielding [κ³P,N,P-HN(CH₂CH₂NHPiPr₂)₂NiMe]I (10), [κ³P,N,P-HN(CH₂CH₂NHPiPr₂)₂MMe]I (M = Pd 8b Pt 11) and [κ³P,S,P-S(CH₂CH₂NHPiPr₂)₂MMe]I (M = Pd 9b, Pt 12). Alternatively, use of NEt₃HCl in place of MeI produces the species [κ³P,N,P-HN(CH₂CH₂NHPiPr₂)₂MH]X (X = Cl, M = Ni 13a, Pd 14a, Pt 16a). The analogs containing 2; [κ³P,S,P-S((CH₂)₂NHPiPr₂)₂MH]X (M = Pd, X = PF₆15: M = Pt, X = Br, 17a, PF₆17b) were also prepared in yields ranging from 74–93%. In addition, aryl halide oxidative addition was also employed to prepare [κ³P,N,P-HN(CH₂CH₂NHPiPr₂)₂MC₆H₄F]Cl (M = Ni 18, Pd 19) and [κ³P,S,P-S((CH₂)₂NHPiPr₂)₂Pd(C₆H₄F)]Cl (20). Crystal structures of 3a, 4a, 5a, 6a, 8a, 9a, 14b and 16b are reported.