Synthesis and characterization of tris(heteroleptic) Ru(II) complexes bearing styryl subunits

We have developed and optimized a well-controlled and refined methodology for the synthesis of substituted π-conjugated 4,4'-styryl-2,2'-bipyridine ligands and also adapted the tris(heteroleptic) synthetic approach developed by Mann and co-workers to produce two new representative Ru(II)-based complexes bearing the metal oxide surface-anchoring precursor 4,4'-bis[E-(p-methylcarboxy-styryl)]-2,2'-bipyridine. The two targeted Ru(II) complexes, (4,4'-dimethyl-2,2'-bipyridine)(4,4'-di-tert-butyl-2,2'-bipyridine)(4,4'-bis[E-(p-methylcarboxy-styryl)]-2,2'-bipyridine) ruthenium(II) hexafluorophosphate, [Ru(dmbpy)(dtbbpy)(p-COOMe-styryl-bpy)](PF(6))(2) (1) and (4,4'-dimethyl-2,2'-bipyridine)(4,4'-dinonyl-2,2'-bipyridine)(4,4'-bis[E-(p-methylcarboxy-styryl)]-2,2'-bipyridine) ruthenium(II) hexafluorophosphate, [Ru(dmbpy)(dnbpy)(p-COOMe-styryl-bpy)](PF(6))(2) (2) were obtained as analytically pure compounds in high overall yields (>50% after 5 steps) and were isolated without significant purification effort. In these tris(heteroleptic) molecules, NMR-based structural characterization became nontrivial as the coordinated ligand sets each sense profoundly distinct magnetic environments greatly complicating traditional 1D spectra. However, rational two-dimensional approaches based on both homo- and heteronuclear couplings were readily applied to these structures producing quite definitive analytical characterization and the associated methodology is described in detail. Preliminary photoluminescence and photochemical characterization of 1 and 2 strongly suggests that both molecules are energetically and kinetically suitable to serve as sensitizers in energy-relevant applications.     

cis-Bis(bipyridine)ruthenium Imidazole Derivatives: A Spectroscopic, Kinetic, and Structural Study

The ruthenium bis(bipyridine) complexes cis-[Ru(bpy)(2)Im(OH(2))](2+), cis-[Ru(bpy)(2)(Im)(2)](2+), cis-[Ru(bpy)(2)(N-Im)(2)](2+), cis-[Ru(dmbpy)(2)Im(OH(2))](2+), cis-[Ru(dmbpy)(2)(N-Im)(OH(2))](2+)(bpy = 2,2'-bipyridine, dmbpy = 4,4'-dimethyl-2,2'-bipyridine, Im = imidazole, N-Im = N-methylimidazole), have been synthesized under ambient conditions in aqueous solution (pH 7). Their electrochemical and spectroscopic properties, absorption, emission, and lifetimes were determined and compared. The substitution kinetics of the cis-[Ru(bpy)(2)Im(OH(2))](2+) complexes show slower rates and have lower affinities for imidazole ligands than the corresponding cis-[Ru(NH(3))(4)Im(OH(2))](2+) complexes. The crystal structures of the monoclinic cis-[Ru(bpy)(2)(Im)(2)](BF(4))(2), space group = P2(1)/a, Z = 4, a = 11.344(1) ?, b = 17.499(3) ?, c = 15.114(3) ?, and beta = 100.17(1) degrees, and triclinic cis-[Ru(bpy)(2)(N-Im)(H(2)O)](CF(3)COO)(2).H(2)O, space group = P&onemacr;, Z = 2, a = 10.432(4) ?, b = 11.995(3) ?, c = 13.912(5) ?, alpha = 87.03(3) degrees, beta = 70.28(3) degrees, and gamma = 71.57(2) degrees, complexes show that these molecules crystallize as complexes of octahedral Ru(II) to two bidentate bipyridine ligands with two imidazole ligands or a water and an N-methylimidazole ligand cis to each other. The importance of these molecules is associated with their frequent use in the modification of proteins at histidine residues and in comparisons of the modified protein derivatives with these small molecule analogs.     

Electrochemical and luminescent properties of new mononuclear ruthenium(II) and binuclear iridium(III)-ruthenium(II) terpyridine complexes.

Hexafluorophosphate salts of mononuclear complexes [Ru(II)Cl(L)(terpy)]+ (L = dmbpy (1); dpbpy (2), sambpy (3), and dpp (7), and binuclear complexes [Ru(II)2Cl2(dpp)(terpy)2]2+ (8) and [Ir(III)Ru(II)Cl2(dpp)(terpy)2]3+ (9) were prepared and characterized. Abbreviations of the ligands are bpy = 2,2'-bipyridine, dmbpy = 4,4'-dimethyl-2,2'-bipyridine, dpbpy = 4,4'-diphenyl-2,2'-bipyridine, dpp = 2,3-bis(2-pyridyl)pyrazine, sambpy = 4,4'-bis((S)-(+)-alpha-1-phenylethylamido)-2,2'-bipyridine, and terpy = 2,2':6',2'-terpyridine. The absorption spectra of 8 and 9 are dominated by ligand-centered bands in the UV region and by metal-to-ligand charge-transfer bands in the visible region. The details of their spectroscopic and electrochemical properties were investigated. In both binuclear complexes, it has been found that the HOMO is based on the Ru metal, and LUMO is dpp-based. [Ir(III)Ru(II)Cl2(dpp)(terpy)2]3+, indicating intense emission at room temperature, and a lifetime of 154 ns. The long lifetime of this bimetallic chromophore makes it a useful component in the design of supramolecular complexes.     

Syntheses, structures, and optical properties of novel zinc(ii) complexes with multicarboxylate and N-donor ligands

Five novel coordination polymers [Zn(2)(OA)(4,4'-bipy)(H(2)O)].0.5(4,4'-bipy), [Zn(2)(OA)(dib)(H(2)O)].H(2)O, [Zn(2)(OA)(bbi)(2)].3H(2)O, [Zn(2)(OA)(phen)(2)(H(2)O)] and [Zn(4)(OA)(2)(2,2'-bipy)(2)(H(2)O)].2H(2)O were obtained by hydrothermal reactions of Zn(NO(3))(2).6H(2)O with a V-shaped multicarboxylate ligand 3,3',4,4'-oxydiphthalic acid (H(4)OA) and a series of N-donor ligands, namely 4,4'-bipyridine (4,4'-bipy), 1,4-di(1-imidazolyl)benzene (dib), 1,1'-(1,4-butanediyl)bis(imidazole) (bbi), 1,10-phenanthroline (phen), 2,2'-bipyridine (2,2'-bipy). The structures of the complexes were established by single-crystal X-ray diffraction analysis. Complex exhibits a robust 3D porous structure with uncoordinated 4,4'-bipy molecules filling the cavities. Complexes and show a complicated 3D framework, while complexes and have a 2D network and a 1D helical chain structure, respectively. The results indicate that the multicarboxylate OA(4-) ligand can adopt varied coordination modes in the formation of the complexes and the influence of the N-donor ligand on the structure of the complexes is discussed. The photoluminescence properties of H(4)OA and were studied in the solid state at room temperature. Moreover, nonlinear optical measurements showed that displayed a second-harmonic-generation (SHG) response of 0.5 times of that for urea. The results suggested that the configuration and flexibility of the ligands play a key role in directing the related properties of the complexes.     

Synthesis, Characterization, Spectroscopic and Electro-chemical Properties of New Mono- and Binuclear Copper(I) Complexes with Substituted 2,2''''-Bipyridine

Introduction Copper(I) complexes have received much attention for their being less expensive and environmentally friendly, various coordination geometry, rich photo-chemical and photophysical properties.1-7 It is well known that copper complexes with diimine (2,2'-bipy- ridine, 1,10-phenanthroline and their substituted deriva-tives designated as diimine) generally exhibit low en-ergy metal-to-ligand charge-transfer (MLCT) states lo-cated in the regions of 350650 nm (e ≈ 103—104 dm3昺ol-1昪…     

Synthesis and structural,electrochemical, and optical properties of Ru(II) complexes with azobis(2,2'-bipyridine)s

Two new ditopic ligands, 5,5"-azobis(2,2'-bipyridine) (5,5"-azo) and 5,5"-azoxybis(2,2'-bipyridine) (5,5"-azoxy), were prepared by the reduction of nitro precursors. Mononuclear and dinuclear Ru(II) complexes having one of these bridging ligands and 2,2'-bipyridine terminal ligands were also prepared, and their properties were compared with previously reported Ru(II) complexes having 4,4"-azobis(2,2'-bipyridine) (4,4"-azo). The X-ray crystal structure showed that 5,5"-azo adopts the trans conformation and a planar rodlike shape. The X-ray crystal structure of [(bpy)(2)Ru(5,5"-azo)Ru(bpy)(2)](PF(6))(4) (Ru(5,5"-azo)Ru) showed that the bridging ligand is in the trans conformation and nearly planar also in the complex and the metal-to-metal distance is 10.0 A. The azo or azoxy ligand in these complexes exhibits reduction processes at less negative potentials than the terminal bpy's due to the low-lying pi level. The electronic absorption spectra for the complexes having 5,5"-azo or 5,5"-azoxy exhibit an extended low-energy metal-to-ligand charge-transfer absorption. The ligands, 5,5"-azo and 5,5"-azoxy, and the mononuclear complex, [(bpy)(2)Ru(5,5"-azo)](2+), isomerize reversibly upon light irradiation. The low-energy MLCT state sensitizes the isomerization of the azo moiety in this complex. While [(bpy)(2)Ru(4,4"-azo)Ru(bpy)(2)](PF(6))(4) exhibits light switch properties, namely, significant electrochromism and a large luminescence enhancement, upon reduction, Ru(5,5"-azo)Ru does not show these properties. The radical anion formation upon reduction of these complexes has been confirmed by ESR spectroscopy.     

Syntheses, structures, and characterizations of four new lead(II) 5-sulfosalicylate complexes with both chelating and bridging neutral ligands

Four structurally diverse complexes, {[Pb(Hssal)(2,2'-bipy)](4,4'-bipy)0.5}n (1), [Pb2(Hssal)2(2,2'-bipy)2(4,4'-bipy)(H2O)2] (2), [Pb(Hssal)(phen)(4,4'-bipy)0.5]n (3), and [Pb(Hssal)(2,2'-bipy)(bpe)0.5]n (4), have been synthesized and characterized by elemental analyses, IR, thermogravimetric analyses, fluorescent spectra, and single-crystal X-ray analyses, where Hssal2- is doubly deprotonated 5-sulfosalicylate, 2,2'-bipy is 2,2'-bipyridine, phen is 1,10-phenanthroline, 4,4'-bipy is 4,4'-bipyridine, and bpe is trans-1,2-bis(4-pyridyl)ethylene. The structure of complex 1 possesses a one-dimensional ladderlike chain with guest 4,4'-bipy molecules, while the molecular structure of complex 2 is a dimeric species with a coordinating 4,4'-bipy ligand. Complex 3 consists of a one-dimensional ladderlike chain with monodentate 4,4'-bipyridine but somewhat different from that of complex 1. Complex 4 is a two-dimensional layer structure. In 1-4, all 5-sulfosalicylates are doubly deprotonated, and all carboxylate groups of Hssal2- chelate to PbII ions; however, the coordination modes of sulfonyl groups are different: syn-syn bridging in 1, noncoordinating in 2, syn-skew bridging in 3, and one-atom bridging in 4. The noncoordinating mode of sulfonate in PbII complexes containing 5-sulfosalicylate is first reported in this presentation. The 4,4'-bipy ligands act as guest molecules in 1, dimeric linkers in 2, and monodentates in 3. The pi-pi stacking interactions can be observed in complexes 1-3, whereas there is no such interaction in complex 4. The coordination spheres of PbII ions in 1-4 are controlled by three factors: the activity of a lone pair of electrons, weak Pb-O interactions, and pi-pi stacking interactions. The PbII lone pair in 4 is inactive, whereas in 1-3, they are stereochemically active. The thermal stability and fluorescent property of complexes 1-4 are different from those of PbII complexes only containing chelating ligands, [Pb(Hssal)(2,2'-bipy)(DMF)]n (5), and [Pb(Hssal)(2,2'-bipy)(H2O)]n (6), and [Pb(Hssal)(phen)(DMF)]n (7).     

Square Planar (SP-4) and Octahedral (OC-6) Complexes of Platinum(II) and -(IV) with Predetermined Chirality at the Metal Center

cis-Bis-homoleptic platinum(II) complexes, with predetermined helical chirality at the metal center, can be obtained by using strongly sterically interacting ligands. With this aim, two new ligands, (8R,10R)-2-(2'-thienyl)-4,5-pinenopyridine, th4,5ppy (2), and (8R,10R)-2-(2'-thienyl)-5,6-pinenopyridine, th5,6ppy (4), were synthesized and coordinated to platinum. The structures of the resulting complexes, Pt(th4,5ppy)(2) (5) and Pt(th5,6ppy)(2) (6), were determined by X-ray diffraction, and it was found that they both crystallize with a Delta-cis configuration. Thermal oxidative additions (TOA) of alkyl halides were performed with both complexes leading, in the case of 5, to a mixture of isomers and, in the case of 6, to isomerically pure products. The predetermination of chirality at the metal center is therefore preserved in the octahedral (OC-6) platinum(IV) complexes. Crystals of Pt(th4,5ppy)(2) (5) are orthorhombic, of space group P2(1)2(1)2(1), with a = 12.973(1) ?, b = 13.619(2) ?, c = 17.665(2) ?, alpha = beta = gamma = 90 degrees, and Z = 4. Final R = 0.0268 and R(w) = 0.0424 for 3101 observed reflections. Crystals of Pt(th5,6ppy)(2) (6) are hexagonal, of space group P6(1), with a = 11.5465(4) ?, b = 11.5465(4) ?, c = 35.356(3) ?, alpha = beta = 90 degrees, gamma = 120 degrees, and Z = 6. Final R = 0.0424 and R(w) = 0.0845 for 2660 observed reflections. Neither molecule possesses a crystallographic C(2) symmetry.     

Novel synthetic routes to several new, differentially substituted ruthenium tris(4,4 disubstituted-2,2-bipyridine) complexes

The stepwise synthesis of several novel Ru(tris(pp)) complexes (pp = 4,4'-disubstituted-2,2'-bipyridine; substituent = H, Me, chiral ester, or chiral amide) is described, where the pp ligands may be the same, or different, in each complex. All of the complexes detailed have been resolved into their pure delta- and lambda-enantiomers or diastereomers. The complexes, which are prepared starting from RuCl3, contain novel ligand architectures, with a range of chiral esters and amides attached to the 4,4'-positions of the bpy ligands. It was postulated that these chiral groups would be capable of inducing chirality at the metal center, but our investigations have shown this not to be the case, and in all reactions completely racemic products were formed. Resolution by chiral HPLC, and the subsequent characterization of the products through NMR, UV-vis, and circular dichroism (CD) spectroscopy, has been carried out; the characteristics of the CD spectra have been discussed with respect to the electron-donating/ withdrawing ability of the groups at the 4,4'-positions. The X-ray crystal structure of the optically pure complex lambda-[Ru(dmbpy)2(4,4'-bis((R)-(+)-alpha-phenylethylamido)-2,2'-bipyridine)] x 2PF6 x 2CHCl3 was obtained and solved using direct methods. This result, in conjunction with the CD spectra, enabled the complete and unambiguous assignment of the stereocenters of all of the novel Ru(tris(bpy)) complexes prepared in this investigation.     

New synthetic routes to biscarbonylbipyridinerhenium(I) complexes cis,trans-[Re(X2bpy)(CO)2(PR3)(Y)n+ (X2bpy = 4,4'-X2-2,2'-bipyridine) via photochemical ligand substitution reactions, and their photophysical and electrochemical properties

Photochemical ligand substitution of fac-[Re(X2bpy)(CO)3(PR3)]+ (X2bpy = 4,4'-X2-2,2'-bipyridine; X = Me, H, CF3; R = OEt, Ph) with acetonitrile quantitatively gave a new class of biscarbonyl complexes, cis,trans[Re(X2bpy)(CO)2(PR3)(MeCN)]+, coordinated with four different kinds of ligands. Similarly, other biscarbonylrhenium complexes, cis,trans-[Re(X2bpy)(CO)2(PR3)(Y)]n+ (n = 0, Y = Cl-; n = 1, Y = pyridine, PR'3), were synthesized in good yields via photochemical ligand substitution reactions. The structure of cis,trans-[Re(Me2bpy)(CO)2[P(OEt)3](PPh3)](PF6) was determined by X-ray analysis. Crystal data: C38H42N2O5F6P3Re, monoclinic, P2(1/a), a = 11.592(1) A, b = 30.953(4) A, c = 11.799(2) A, V = 4221.6(1) A3, Z = 4, 7813 reflections, R = 0.066. The biscarbonyl complexes with two phosphorus ligands were strongly emissive from their 3MLCT state with lifetimes of 20-640 ns in fluid solutions at room temperature. Only weak or no emission was observed in the cases Y = Cl-, MeCN, and pyridine. Electrochemical reduction of the biscarbonyl complexes with Y = Cl- and pyridine in MeCN resulted in efficient ligand substitution to give the solvento complexes cis,trans-[Re(X2bpy)(CO)2(PR3)(MeCN)]+.     

Synthesis,characterization, and polymerization activity of [bis(4,4'-bis(neophyldimethylsilylmethyl)-2,2'-bipyridyl)copper(I)]+CuBr2- and Implications for copper(I) catalyst structures in atom transfer radical polymerization

A series of 4,4'-disilyl-substituted-2,2'-bipyridine ligands were prepared using a metathesis reaction of the dianion of 4,4'-dimethyl-2,2'-bipyridine with several trialkylsilyl chlorides: 4,4'bis(tert-butyldimethylsilylmethyl)-2,2'-bipyridine (dTBDMSbipy), 4,4'-bis(dimethylthexylsilylmethyl)-2,2'-bipyridine (dTHEXbipy), and 4,4'-bis(neophyldimethylsilylmethyl)-2-2'-bipyridine (dNEObipy). It was observed that the side chain length correlated with the ability of the ligand to form hydrocarbon soluble complexes of copper(I) bromide, with dNEObipy forming the most soluble and easily crystallized complexes. The atom transfer radical polymerization (ATRP) of styrene using dNEObipy as the ligand displayed molecular weight control equivalent to other ATRP systems in which solubilizing ligands, such as 4,4'-di-5-nonyl-2,2'-bipyridine or 4,4'-di-n-heptyl-2,2'-bipyridine, were used. The one-to-one complex of dNEObipy with CuBr was prepared and its crystal structure was determined. The resulting complex had the ionic formulation [(dNEObipy)2Cu]+[CuBr2]- and displayed similar activities in styrene ATRP as the standard 2 dNEObipy/CuBr catalyst system. These and other polymerization results in addition to NMR experiments suggest that the predominant copper(I) species formed in ATRP solutions is the 2-to-1 ligand-to-copper(I) cation, [(dNEObipy)2Cu]+, with either a dihalocuprate or halide counteranion, depending upon the conditions.     

Syntheses,crystal structures,and physical properties of dinuclear copper(I) and tetranuclear mixed-valence copper(I,II) complexes with hydroxylated bipyridyl-like ligands

Four copper complexes with hydroxylated bipyridyl-like ligands, namely [Cu(2)(ophen)(2)] (1), [Cu(4)(ophen)(4)(tp)] (2), [Cu(4)(obpy)(4)(tp)] (3), and [Cu(4)(obpy)(4)(dpdc)].2H(2)O (4), (Hophen=2-hydroxy-1,10-phenanthroline, Hobpy=6-hydroxy-2,2'-bipyridine, tp=terephthalate, dpdc=diphenyl-4,4'-dicarboxylate) have been synthesized hydrothermally. X-ray single-crystal structural analyses of these complexes reveal that 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy) ligands are hydroxylated into ophen or obpy during the reaction, which provides structural evidence for the long-time argued Gillard mechanism. The dinuclear copper(I) complex 1 has three supramolecular isomers in the solid state, in which short copper-copper distances (2.66-2.68 A) indicate weak metal-metal bonding interactions. Each of the mixed-valence copper(i,ii) complexes 2-4 consists of a pair of [Cu(2)(ophen)(2)](+) or [Cu(2)(obpy)(2)](+) fragments bridged by a dicarboxylate ligand into a neutral tetranuclear dumbbell structure. Dinuclear 1 is an intermediate in the formation of 2 and can be converted into 2 in the presence of additional copper(II) salt and tp ligands under hydrothermal conditions. In addition to the ophen-centered pi-->pi* excited-state emission, 1 shows strong emissions at ambient temperature, which may be tentatively assigned as an admixture of copper-centered d-->s,p and MLCT excited states.     

Insertion reactions of SO2 into Pd-OR bonds: preparation of alkyl sulfito complexes of palladium(II)

Mononuclear palladium-hydroxo complexes of the type [Pd(N-N)(C6F5)(OH)][(N-N = 2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me2bipy), or N,N,N',N'-tetramethylethylenediamine (tmeda) react with SO2(1 atm) at room temperature in alcohol (methanol, ethanol, propanol or isopropanol) to yield alkyl sulfito palladium complexes [Pd(N-N)(C6F5)(SO2OR)](R = Me, Et, Pr or iPr). Similar alkyl sulfito complexes [Pd(N-N)(C6F5)(SO2OR)](N-N = bis(3,5-dimethylpyrazol-1-yl)methane); R = Me or Et) are obtained when [Pd(N-N)(C6F5)Cl] is treated with KOH in the corresponding alcohol ROH and SO2 is bubbled through the solution. The reaction of [Pd(bipy)(C6F5)(OH)] with SO2 in tetrahydrofuran gives [Pd(N-N)(C6F5)(SO2OH)]. The X-ray diffraction study of [Pd(tmeda)(C6F5)(SO2OPr)] has established the sulfur coordination of the propyl sulfito ligand.     

New ruthenium(II) complexes functionalized with coumarin derivatives: synthesis, energy-transfer-based sensing of esterase, cytotoxicity, and imaging studies

Two new bichromophoric ruthenium(II) complexes, [Ru(bpy)(2)(bpy-CM)](PF(6))(2) and [Ru(bpy)(2)(bpy-CM343)](PF(6))(2) (bpy=2,2'-bipyridine, CM=coumarin) with appended coumarin ligands have been designed and synthesized. The energy-transfer-based sensing of esterase by the complexes has been studied by using UV/Vis and luminescence spectroscopic methods. The cytotoxicity and the cellular uptake of one of the complexes have also been investigated.     

Electrochemical and phosphorescent properties of new mixed-ligand Ir(II) complexes coordinated with both terpyridine and various bipyridine derivatives.

Seven useful mixed-ligand complexes in the form of [Ir(terpy)(L)Cl]2+ were prepared and their spectroscopic and electrochemical properties were investigated. The ligands used were terpy = 2,2':6',2'-terpyridine, L = 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 4,4'-diphenyl-2,2'-bipyridine, 1,10-phenanthroline, 5-phenyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, 2,3-bis(2-pyridyl)pyrazine. Synthetic methods were developed by a sequential ligand-replacement which occurred in the reaction vessel using a microwave oven. All complexes showed that LUMOs are based on the pi-system contribution of the terpyridine ligand for [Ir(terpy)(bpy)Cl]2+, [Ir(terpy)(dmbpy)Cl]2+, [Ir(terpy)(dpbpy)Cl]2+, [Ir(terpy)(phen)Cl]2+, [Ir(terpy)(dpphen)Cl]2+ and [Ir(terpy)(phphen)Cl]2+. On the other hand, the LUMO in the [Ir(terpy)(bppz)Cl]2+ complex is localized on the pi-system of the bppz ligand, whereas the HOMOs in the iridium complexes are localized on the terpyridine ligand. It was found that Ir(terpy)(L)Cl emits in a fluid solution at room temperature. The ancillary ligands, such as terpy and bpy, have been explored to extend the lifetime of the triplet 3(pi-pi') excited states of Ir(III) terpyridine complexes. Ir(III) terpyridine units with an electron donor (dmbpy) or electron acceptor substituents (terpy, dpbpy, phphen, dpphen and bppz) are found to decrease the energy of the 3LC states for use as photosensitizer molecular components in supramolecular devices. The spectroscopic and electrochemical details are also reported herein.     

Synthesis of heteroleptic bis(diimine)carbonylchlororuthenium(II) complexes from photodecarbonylated precursors

The reactions of bidentate diimine ligands (L2) with binuclear [Ru(L1)(CO)Cl2]2 complexes [L1 not equal to L2 = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (4,4'-Me2bpy), 5,5'-dimethyl-2,2'-bipyridine (5,5'-Me2bpy), 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (4,7-Me2phen), 5,6-dimethyl-1,10-phenanthroline (5,6-Me2phen), di(2-pyridyl)ketone (dpk), di(2-pyridyl)amine (dpa)] result in cleavage of the dichloride bridge and the formation of cationic [Ru(L1)(L2)(CO)Cl]+ complexes. In addition to spectroscopic characterization, the structures of the [Ru(bpy)(phen)(CO)Cl]+, [Ru(4,4'-Me2bpy)(5,6-Me2phen)(CO)Cl]+ (as two polymorphs), [Ru(4,4'-Me2bpy)(4,7-Me2phen)(CO)Cl]+, [Ru(bpy)(dpa)(CO)Cl]+, [Ru(5,5'-Me2bpy)(dpa)(CO)Cl]+, [Ru(bpy)(dpk)(CO)Cl]+, and [Ru(4,4'-Me2bpy)(dpk)(CO)Cl]+ cations were confirmed by single crystal X-ray diffraction studies. In each case, the structurally characterized complex had the carbonyl ligand trans to a nitrogen from the incoming diimine ligand, these complexes corresponding to the main isomers isolated from the reaction mixtures. The synthesis of [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)(NO3)]+ from [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)Cl]+ and AgNO3 demonstrates that exchange of the chloro ligand can be achieved.     

Crystal Structures and Luminescence Properties of Platinum(II) Complexes Containing 3,3'-Biisoquinoline

Three new platinum complexes containing 3,3'-biisoquinoline (i-biq), [Pt(CN)(2)(i-biq)] (1), [PtCl(2)(i-biq)] (2), and [Pt(i-biq)(2)](PF(6))(2) (3), have been synthesized as orange-red, yellow, and colorless crystals, respectively. Their crystal structures and luminescence properties are reported. Crystal data: for 1.0.5H(2)O, PtO(0.5)N(4)C(20)H(13), orthorhombic, Pbcm, a = 13.989(2) ?, b = 18.304(1) ?, c = 6.682(3) ?, V = 1710.9(6) ?(3), Z = 4, and final R = 0.039 (R(w) = 0.033) for 970 independent reflections; for 2.DMF.H(2)O, PtCl(2)O(2)N(3)C(21)H(21), triclinic, P&onemacr;, a = 11.047(1) ?, b = 12.397(3) ?, c = 8.000(2) ?, alpha = 106.56(1) degrees, beta = 100.15(1) degrees, gamma = 76.15(1) degrees, V = 1012.8(3) ?(3), Z = 2, and final R = 0.058 (R(w) = 0.077) for 4219 independent reflections; for 3.2DMF, PtP(2)F(12)O(2)N(6)C(42)H(38), triclinic, P&onemacr;, a = 10.795(2) ?, b = 13.511(2) ?, c = 8.281(1) ?, alpha = 105.22(1) degrees, beta = 112.17(1) degrees, gamma = 85.02(1) degrees, V = 1079.2(3) ?(3), Z = 1, and final R = 0.038 (R(w) = 0.042) for 3606 independent reflections. Square-planar complexes of 1 are stacked in the crystal to form a columnar structure with the Pt-Pt distance of 3.34 ?. The crystal emits strongly, even at room temperature, and the emission spectrum is similar to that for the [Pt(CN)(2)(bpy)] crystal (bpy = 2,2'-bipyridine), which is due to a (3)dpi[dsigma(Pt) --> pi(i-biq)] transition. The single crystal emission spectrum at 77 K is, however, observed as a superposition of broad (3)dpi and sharp (3)pipi(i-biq) emissions. The crystal structure of 2 has a completely different stacking structure from that of 1. The stacking occurs on the i-biq ligands, and the Pt atoms are separated more than 6 ?. The complex exhibits only a structured emission component assigned to the (3)pipi(i-biq) transition in the crystal at 77 K, in agreement with the crystal structure with no Pt-Pt interaction. In the crystal of 3, the [Pt(i-biq)(2)](2+) complexes are stacked but offset, being in close contact between parts of adjacent i-biq ligands. There is no Pt-Pt interaction also in this case. Two i-biq ligands in the complex are distorted to adopt the bowed conformation due to the steric crowding of the alpha-hydrogens on opposite ligands. Nevertheless, 3 provides almost the same (3)pipi emission spectrum as 1 and 2 in dilute glassy solution at 77 K. The (3)pipi emission spectra observed in the crystals of these Pt(II) complexes are red-shifted compared with those in dilute glassy solution. The fact is attributable to the pi-pi intermolecular interactions between the ligands in the crystals. The factors controlling the crystal structures for these complexes are also discussed.     

Combined effects of diamines and carboxylate bridges on structural and magnetic properties of a series of polynuclear copper(II) complexes with 1,1-cyclobutanedicarboxylic acid

Six new copper(II) complexes of formula [Cu(mu-cbdca)(H2O)]n (1) (cbdca = cyclobutanedicarboxylate), [Cu2(mu-cbdca)2(mu-bipy)2]n (2) (bipy = 4,4'-bipyridine), [Cu(mu-cbdca)(mu-bpe)]n (3) (bpe = 1,2-bis(4-pyridyl)ethane), [Cu(mu-cbdca)(bpy)]2 (4) (bpy = 2,2'-bipyridine), [Cu(terpy)(ClO4)]2(mu-cbdca).H2O (5) (terpy = 2,2':6',2' '-terpyridine), and [Cu(cbdca)(phen) (H2O)].2H2O (6) (phen = 1,10-phenanthroline) were obtained and structurally characterized by X-ray crystallography. Complex 1 is a two-dimensional network with a carboxylate bridging ligand in syn-anti (equatorial-equatorial) coordination mode. Complexes 2 and 3 are formed by chains through syn-anti (equatorial-apical) carboxylate bridges, linked to one another by the corresponding amine giving two-dimensional nets. Complexes 4 and 5 are dinuclear, with the copper ions linked by two oxo (from two different carboxylate) bridging ligands in 4 and with only one carboxylate showing the unusual bis-unidentate mode in complex 5. Complex 6 is mononuclear, with the carboxylate linked to copper(II) in a chelated form. Intermolecular hydrogen bonds and pi-pi stacking interactions build an extended two-dimensional network. Magnetic susceptibility measurements of complexes 1-5 in the temperature range 2-300 K show the occurrence of weak ferromagnetic coupling for 1 and 4 (J = 4.76 and 4.44 cm(-1), respectively) and very weak antiferromagnetic coupling for 2, 3, and 5 (J = -0.94, -0.67, and -1.61 cm(-1), respectively). Structural features and magnetic values are compared with those reported for the similar copper(II) malonate and phenylmalonate complexes.     

Dinuclear gold(I) isocyanide complexes with luminescent properties, and displaying thermotropic liquid crystalline behavior

Dinuclear gold(I) complexes [mu-(4,4'-CN-R-NC){Au(C6F4OC4H9)}2] [R = 1,4-phenylene, n = 8; R = 4,4'-biphenylene, 2,2'-dichloro-4,4'-biphenylene, 2,2'-dimethyl-4,4'-biphenylene, n = 4,6,8,10] have been prepared and their liquid crystal behavior and optical properties studied. Although the free ligands are not mesomorphic, all the gold(I) derivatives described, except the phenylisonitrilegold(I) derivative [mu-(1,4-CN-C6H4-NC){Au(C6F4OC8H17)}2], display liquid crystal behavior, giving rise to a nematic mesophase. The transition temperatures decrease in the order 4-4'-biphenylene > 2,2'-dichloro-4-4'-biphenylene > 2,2'dimethyl-4-4'-biphenylene. All compounds show photoluminescence in the solid state and in solution. The single-crystal X-ray diffraction structures of [mu-(4,4'-CN-R-NC){Au(C6F4OCnH2n+1)}2] (R = 4-4'-biphenylene and 2,2'-dichloro-4-4'-biphenylene) have been determined confirming the rodlike structure of the molecule, with a linear coordination around the gold atoms. There are Au...Au interactions in the 2,2'-dichlorobiphenyl derivative but not in the 4-4'-biphenyl compound.     

Mono- and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes

We report the synthesis of free 1,6,7,12-tetraazaperylene (tape). Tape was obtained from 1,1'-bis-2,7-naphthyridine by potassium promoted cyclization followed by oxidation with air. Mono- and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes of the general formulas [Ru(L-L)(2)(tape)](PF(6))(2), [1](PF(6))(2)-[5](PF(6))(2), and [{Ru(L-L)(2)}(2)(μ-tape)](PF(6))(4), [6](PF(6))(4)-[10](PF(6))(4), with{L-L = phen, bpy, dmbpy (4,4'-dimethyl-2,2'-bipyridine), dtbbpy (4,4'-ditertbutyl-2,2'-bipyridine) and tmbpy (4,4'5,5'-tetramethyl-2,2'-bipyridine)}, respectively, were synthesized. The X-ray structures of tape·2CHCl(3) and the mononuclear complexes [Ru(bpy)(2)(tape)](PF(6))(2)·0.5CH(3)CN·0.5toluene, [Ru(dmbpy)(2)(tape)](PF(6))(2)·2toluene and [Ru(dtbbpy)(2)(tape)](PF(6))(2)·3acetone·0.5H(2)O were solved. The UV-vis absorption spectra and the electrochemical behavior of the ruthenium(ii) tape complexes were explored and compared with the data of the analogous dibenzoeilatin (dbneil), 2,2'-bipyrimidine (bpym) and tetrapyrido[3,2-a:2',3'-c:3',2'-h:2',3'-j]phenazin (tpphz) species.