The coordination behavior prior to C-M bond formation of the chelating aromatic PCP substrate DPPMH (3; DPPMH = l,3-bis((diphenylphosphino)methylene)mesitylene) has been studied in order to determine the factors which control the complex formation of such ligands. Reacting 3 with (RCN)2MCl2 (R = Me, Ph; M = Pd, Pt) and (COD)PtX2 (X = Cl, Me; COD = 1,5-cyclooctadiene) resulted in the formation of several 8- and 16-membered mono- and binuclear palladium(II) and platinum(II) macrocycles: trans-[(DPPMH)PdCl2]2 (5), trans-[(DPPMH)-PtCl2]2 (6), cis-(DPPMH)PtCl2 (7), cis-(DPPMH)PtMe2 (8), and cis-[(DPPMH)PtMe2]2 (9). Compounds 5-9 were fully characterized using NMR, FAB-MS, FD-MS, elemental analysis, and X-ray crystallography. Thermolysis of the bimetallic trans-[(DPPMH)PtCl2]2 (6) results in the formation of the monomeric cis-(DPPMH)PtCl2 (7). The product formation depends on the neutral- (nitriles or COD) and anionic ligands (Cl and CH3) of the metal precursor. The molecular structures of trans-[(DPPMH)PdCl2]2 (5) and cis-[(DPPMH)PtMe2]2 (9) have been determined by complete single-crystal diffraction studies. Crystal data for 5: monoclinic, space group P21 /n with a = 14.547(3) Å, b = 17.431(4) Å, c = 27.839 (5) Å, β= 99.56(2)°, V = 6961(3) Å3, and Z = 4. The structure converged to R = 0.048 and Rw = 0.049. Crystal data for 9: monoclinic, space group P21/n with a = 19.187(4) Å, b = 19.189(4) Å c = 20.705(2) Å, β= 103.41(3)°, V = 7415(3) Å3, and Z = 4. The structure refinement converged to R = 0.0977 and Rw = 0.2212.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry