A total of 21 complexes of CuX (X = Cl, Br, I) with bridging ligand (B = 4,4'-dipyridyl (Bpy), pyrazine (Pyz), quinoxaline (Quin), phenazine (Phz), 1,4-diazabicyclo[2.2.2]octane (DABCO), and hexamethylenetetramine (HMTA)) have been synthesized. The products show two stoichiometries: [CuXB] (type 1) and [(CuX)2B] (type 2). Both types can be obtained for B = Bpy, depending on the conditions of preparation. In these cases, the type 2 stoichiometry is the kinetic product. Type 2 complexes only are found for B = Pyz (X = I), Quin, Phz, DABCO, and HMTA. Type 1 complexes form for Pyz (X = Cl, Br). Thermogravimetic analyses of the complexes reveal the general decomposition trend: 1 --> 2 --> [(CuX)2B(1/2)] --> CuX. The X-ray crystal structure of [CuBr(Pyz)] (type 1) features copper atoms bridged by Br and Pyz, forming 2D sheets of fused rectangular Cu4Br2(Pyz)2 units. The X-ray structure of [(CuI)2(Quin)] (type 2) shows 2D layers composed of [Cu2I2]infinity "stair step" chains which are cross-linked by Quin ligands. A total of 16 complexes of CuXL (L = P(OPh)3) with bridging ligand (B = those above and 1,4-dimethylpiperazine (DMP)) have also been prepared. All of these products, except those of HMTA, are of type 3 formulation, [(CuXL)2B]. The HMTA products have the formula [CuX(HMTA)], type 4. Thermal decomposition of the type 3 and 4 complexes occurs with initial loss of B, L, or both. The X-ray structures of [(CuBrL)2(Bpy)] and [(CuBrL)2(Pyz)] (type 3) reveal 1D chains formed from rhomboidal (LCu)2Br2 units linked by the B ligand. The type 4 structure of [CuBrL(HMTA)] is shown by X-ray to be a simple halide-bridged dimer.

Dipyridylquinoxaline (dpq), 4-cyanopyridine (4-CNpy), 4,4Ј-bipyridine (4,4Ј-bpy) and quinoxaline form n→ * charge-transfer complexes with iodine (I 2 ), in which the N ؒ ؒ ؒ I distance [2.532(3) Å for dpqؒI 2 ; 2.543(9) and 2.555(9) Å for 4-CNpyؒI 2 ; 2.406(7) Å for 4,4Ј-bpyؒ2I 2 ; 2.92(1) and 2.95(1) Å for quinoxؒI 2 ] is shorter than the sum of the van der Waals radii for nitrogen (1.55 Å) and iodine (1.98 Å). Donation of electron density into the antibonding orbital of iodine weakens the I᎐I bond resulting in elongation relative to the value observed in elemental iodine (2.715 Å). Dpq, 4-CNpy and 4,4Ј-bpy form molecular adducts, while quinoxaline forms a polymeric species in which there are interactions at both ends of the I 2 molecule. The type of complex which forms depends on the nucleophilic character of the donor (and its corresponding effect of the I 2 molecule) and on the lattice energy of the complex. The strength of the N ؒ ؒ ؒ I interaction in each of the reported complexes has been investigated by X-ray crystallographic analysis and vibrational spectroscopy (far-IR). All of the complexes undergo thermal decomposition involving loss of I 2 , and their lattice energy, as a function of thermal stability, has been explored.

The oxo-transfer catalyst (nitro)(pyridyl)cobalt(III) tetraphenylporphyrin has been reinvestigated by substitution of the distal pyridine ligand with 4-N,N-dimethylaminopyridine and 3,5-dichloropyridine. Differences in their structures and in the reactivity of the compounds toward catalytic secondary oxo transfer were investigated by FT-IR and UV-visible spectroscopy, cyclic voltammetry, X-ray diffraction, semiempirical calculations, and reactions with alkenes in dichloromethane solution. Very modest differences in the hexacoordinate compounds' structures were predicted and observed, but the secondary oxo-transfer reactivity at the nitro ligand varies markedly with the basicity of the pyridine ligand and the position of the coordination equilibrium. Oxo transfer occurs rapidly through the pentacoordinate species (nitro)cobalt(III) tetraphenylporphyrin that is generated by dissociation of the pyridine ligand and therefore is strongly related to the Hammett parameters of these nitrogenous bases. The reactive pentacoordinate species CoTPP(NO(2)) can be generated in solution by addition of lithium perchlorate to (py)CoTPP(NO(2)) by Lewis acid-base interactions or more simply by using the weaker Lewis base Cl(2)py instead of py as the distal ligand. In contrast to pentacoordinate (nitro)iron porphyrins, disproportionation reactions of CoTPP(NO(2)) compound are not evident. This pentacoordinate derivative, CoTPP(NO(2)), is reactive enough to stoichiometrically oxidize allyl bromide in minutes. Preliminary catalytic oxidation reaction studies of alkenes also indicate the involvement of both radical and nonradical oxo-transfer steps in the mechanism, suggesting formation of a peroxynitro intermediate in the reaction of the reduced CoTPP(NO) with O(2).

The reaction of iodine and 9-methylacridine in methylene chloride results not in the formation of a charge-transfer complex as with acridine, but in the iodine-rich salt [ICH 2 C 13 H 8 N-H] 4 (I 8 )(I 5 ) 2 , 8, where a proton on the methyl group has been replaced by an iodine. In toluene, the reaction produces both a charge-transfer complex ICH 2 C 13 H 8 N-I 2 , 9, and a salt [CH 3 -acridine(H)] 2 (I 7 )(I 5 ), 10. Polyiodide salt formation can be explained by the availability of a facile reaction pathway from the aryl radical cation which results from initial oxidation by I 2 .

The structure of a 1:1 pyrazine-iodine molecular complex has been determined at 203 K and that of a related complex, tetramethylpyrazine-iodine, at 203 and 294 K. Both structures consist of alternating linear chains of diazine and iodine molecules connected through an n-o-* donor-acceptor interaction.