FORMATION OF LUMINESCENT, METAL METAL BONDED, 3/5 COMPLEXES USING PALLADIUM(II) OR PLATINUM(II) AND IRIDIUM(I) THROUGH CHELATE RING OPENINGS

Treatment of Pd(NCC6H5)2Cl2 or K2PtCl4 with 2 equiv of dpmp (dpmp is bis((diphenylphosphino)methyl)phenylphosphine) and ammonium hexafluorophosphate yields yellow [Pd(dpmp)2](PF6)2 or colorless [Pt(dpmp)2](PF6)2, respectively. [Pd(dpmP)2](PF6)2 crystallizes in two forms; yellow crystals of [Pd(dpmp)2](PF6)2.0.5CH2Cl2 form in thc monoclinic space group P2(1)/n (No. 14) with a = 12.494 (3) angstrom, b = 36.639 (15) angstrom, c = 13.912 (5) angstrom, and beta = 90.05 (3)-degrees at 130 K with Z = 4. Refinement of 5487 reflections and 448 parameters gave R = 0.085 and R(w) = 0.10. Apricot colored crystals of [Pd(dpmp)2](PF6)2.(CH3CH2)20 form in the monoclinic space group C2/c (No. 15) with a = 48.88 (2) angstrom, b = 13.731 (4) angstrom, c = 21.387 (7) angstrom, and beta = 95.79 (3)-degrees at 130 K with Z = 8. Refinement of 7502 reflections and 466 parameters gave R = 0.085 and R(w) = 0.114. Both structures consist of the nearly identical cation, [Pd(dpmp)2]2+. The cation contains a square-planar palladium ion with the two dpmp ligands forming both a four-membered and a six-membered chelate ring. Treatment of [Pd(dpmp)2](PF6)2 with either Ir(CO)Cl(AsPh3)2 or Ir(CO)Cl(PPh3)2 yields the 3:5 complex [PdIr(CO)Cl(mu-dpmp)2](PF6)2. Red/orange crystals of [PdIr(CO)Cl(mu-dpmp)2](PF6)2.CHCl3.CH3OH form in the chiral space group P2(1) (No. 4) with a = 13.043 (3) angstrom, b = 19.214 (4) angstrom, c = 14.052 (3) angstrom, and beta = 90.78 (3)-degrees at 130 K with Z = 2. Refinement of 2821 reflections and 424 parameters gave R = 0.050 and R(w) = 0.061. The cation consists of an 18e- Ir center bonded to a 16e- Pd center at a distance of 2.694 (2) k. A dichloromethane solution of [PdIr(CO)Cl(mu-dpmp)2] (PF6)2 shows a strong absorbance at 458 nm (epsilon = 11000 M-1 cm-1) which is assigned to the sigma(M-M) --> sigma*M-M transition. Excitation into this band results in a moderate emission at 520 nm (fluorescence) at 25-degrees-C. Freezing to -196-degrees-C produces emission at 665 nm (phosphorescence). The phosphorescent lifetime was measured at 5-mu-s while the fluorescent lifetime was <350 ns. Similarly addition of Ir(CO)Cl(AsPh3)2 or lr(CO)Cl(PPh3)2 to [Pt(dpmp)2](PF6)2 leads to the formation of yellow [PtIr(CO)Cl(mu-dpmp)2](PF6)2. Yellow crystals of [PtIr(CO)Cl(mu-dpmpp2](PF6)2.0.75CH2Cl2 form in the monoclinic space group P2(1)/c (No. 14) with a = 18.620 (14) angstrom, b = 18.195 (13) angstrom, c = 20.539 (7) angstrom, and beta = 94.03 (5)-degrees at 130 K with Z = 4. Refinement of 9071 reflections and 506 parameters yielded R = 0.069 and R. = 0.080. The Ir-Pt single bond distance is 2.730 (2) angstrom. The structure of [PtIr(CO)Cl(mu-dpmp)2](PF6)2 differs from that of [PdIr(CO)Cl(mu-dpmp)2](PF6)2 in the relative orientation of the dpmp ligands. The absorption spectrum of [PtIr(CO)Cl(mu-dpmp)2](PF6)2 shows a band at 382 nm (epsilon = 19000 M-1 cm-1). At 25-degrees-C there is a moderate emission at 443 nm (fluorescence), and upon freezing to -196-degrees-C, the 443-nm emission disappears, and a new emission at 670 nm (phosphorescence) appears. The phosphorescent lifetime is 27-mu-s while the 443-nm emission is <350 ns.