MONONUCLEAR AND BINUCLEAR PALLADIUM(II) RHENIUM(I) COMPLEXES CONTAINING A STERICALLY HINDERED TRINUCLEATING LIGAND - 5-HEXAMETHYL-5,6,11,12,17,18-HEXAAZATRINAPHTHALENE (HHTN)

The trinucleating ligand 2,3,8,9,14,15-hexamethyl-5,6,11,12,17,18 (hht n), 1, has been obtained in an efficient one-pot synthesis. The reacti on of a yellow-green solution of 1 with 1 equiv of Pd(NCPh)(2)Cl-2 giv es orange PdCl2(hhtn), 2, which crystallizes with two independent PdCl 2(hhtn) molecules, a molecule of chlorobenzene, and two molecules of m ethanol in the triclinic space group P (1) over bar with a 12.949(3) A , b = 16.625(4) Angstrom, c 17.062(4) Angstrom, a 63.00(2)degrees, bet a = 71.39(2)degrees, and gamma = 79.78(2)degrees at 130 K with Z = 4. Refinement of 5551 reflections and 387 parameters yielded R = 0.059 an d R(w) = 0.060. The structure consists of a nearly square planar PdCl2 (N-2) complex in a highly-distorted hhtn framework. Unfavorable Cl... H interactions force the PdCl2 unit out of the hhtn plane by 28.1 degr ees. The structure indicates that there are pi-pi (ligand-ligand) inte ractions. Reaction of 2 with another equivalent of Pd(NCPh)(2)Cl-2 pro duces the binuclear species (PdCl2)(2)(hhtn), 5. Addition of Re(CO)(5) Cl to 1 in refluxing toluene affords deep red crystals of fac-Re(CO)(3 )Cl(hhtn), 3. Dark red needles of Re(CO)(3)Cl(hhtn) CH3OH form in the monoclinic space group P2/n with a 10.515(2) Angstrom, b = 27.123(6) A ngstrom, c 11.385(2) Angstrom, and beta = 110.95(2)degrees at 130 K wi th Z = 4. Refinement of 5451 reflections and 415 parameters yielded R = 0.052 and R(w) = 0.052. The structure features a nearly octahedral R e center that is deflected from the hhtn plane by 19.5 degrees. The hh tn in 3 is less distorted than in 2. Reaction of a dichloromethane sol ution of 3 with 1 equiv of Pd(NCPh)(2)Cl-2 produces the heterobinuclea r (Re(CO)(3)Cl)(PdCl2)(hhtn), 4. Red-brown blocks of 4 cocrystallize w ith 2.6 molecules of 1,2-dichlorobenzene in the triclinic space group P (1) over bar with a 14.540(4) Angstrom, b = 14.558(3) Angstrom, c 14 .671(4) Angstrom, alpha 64.72(2)degrees, 18 = 66.00(2)degrees, and gam ma = 63.30(2)degrees at 130 K with Z = 2. Refinement based on full-mat rix least squares on F-2 using 8481 reflections and 513 parameters yie lded R = 0.061 and R(2) = 0.135. The structure includes a nearly octah edral Re and a square planar Pd coordinated to a highly distorted hhtn ligand. The PdCl2 fragment is bent out of the ligand plane by 40.2 de grees, whereas the Re unit is distorted by only 10.4 degrees. Complex 4 forms pi-pi stacks exclusively with the 1,2-dichlorobenzene solvate molecules.