81603-09-0Relevant articles and documents
Tridentate amido phosphine deriwatives of the nickel triad: Synthesis, characterization, and reactivity of nickel(II), palladlum(II), and platinum(II) amide complexes
Fryzuk, Michael D.,MacNeil, Patricia A.,Rettig, Steven J.,Secco, Anthony S.,Trotter, James
, p. 918 - 930 (2008/10/08)
Deprotonation of HN(SiMe2CH2PPh2)2 (4) with n-butyllithium generates LiN(SiMe2CH2PPh2)2 (5), a tridentate, uninegative ligand which contains both the hard amido donor and soft phosphine donors. The reaction of 5 with each of NiCl2·DME (DME = dimethoxyethane), PdCl2(PhCN)2 and K[PtCl3(C2H4)], generates the corresponding diamagnetic chioro amide derivatives [MClN(SiMe2CH2PPh2)2] (M = Ni, 6; M = Pd. 7; M = Pt, 8), The X-ray structure of the nickel derivative 6 (space group P (Ci1, No. 2) a = 10.091 (3), b = 10.224 (3), c = 17.234 (4) A?; α = 81.06 (2), β= 78.51 (2), γ = 65.93 (3)°; Z = 2; R = 0.029 (Rw = 0.040)) indicates a slightly distorted square-planar geometry with trans phosphine donors. The backbone of the ring is puckered generating near C2 symmetry in the solid state; however, the 1H NMR is consistent with C2v symmetry in solution which can be explained by a rapid conformational flipping of_the ligand backbone. The X-ray structure of the corresponding palladium derivative 7 (space group P1?; a = 11.539 (1), b = 15.368 (2), c = 10.949 (2) A?; α = 92.92 (1), β= 104.09 (1), γ = 84.74 (1)°; Z = 2; R = 0.022 (Rw = 0.031)) also indicates trans phosphines in a square-planar array but with no puckering of the backbone of the ligand. The neutral amine 4 acts as a bidentate ligand via donation through the phosphines to produce the dichloro derivatives [MCl2NH(SiMe2CH2PPh2)2] (M = Ni, 9; M = Pd, 10; M = Pt, 11). The X-ray structure of the nickel derivative 9 (space group P1; a = 10.2224 (1), b = 10.5719 (8), c = 17.770 (2) A?; α = 72.978 (6), β= 78.424 (6), γ = 61.864 (8)°; Z = 2; R = 0.031 (Rw = 0.039)) displays a distorted tetrahedral geometry with no evidence of interaction between the amine portion of the backbone and the metal. Both the palladium, 10, and platinum, 11, derivatives are assumed to be square-planar with cis disposed phosphine donors on the basis of 1 H FT NMR studies. All three dichloro derivatives, 9,10, and 11, are cleanly converted to the corresponding chloro amide complexes, 6, 7, and 8, by treatment with NEt3 in toluene; this reaction requires prior coordination of the phosphine donors in order to activate the distal N-H bond. Metathesis with a number of simple Grignard reagents occurs only for the nickel and palladium chloro amide derivatives, 6 and 7, to generate the metal-carbon bonded complexes [M-(R)N(SiMe2CH2PPh2)2] (M = Ni or Pd; R = CH3, CH=CH2, CH2CH=CH2, or C6H5). The platinum chloride bond of 8 does not undergo metathesis with Grignards and, in addition, is not abstracted with Ag+; consistent with this is the Pt-Cl stretching frequency of 317 cm -1 which is indicative of a weak trans influence for the -N(SiR3)2 ligand.
