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Five new gold complexes 4-RO[C.sub.6][H.sub.4]C = CAuN = C[C.sub.6][H.sub.4]-4-OR' (R/R' = C[H.sub.3]/[C.sub.9][H.sub.19] ([C.sub.1][N.sub.9]), [C.sub.15][H.sub.31]/[C.sub.9][H.sub.19] ([C.sub.15][N.sub.9]), [C.sub.6][H.sub.13]/[C.sub.15][H.sub.31] ([C.sub.6][N.sub.15]), [C.sub.9][H.sub.19]/[C.sub.15][H.sub.31] ([C.sub.9][N.sub.15]), [C.sub.12][H.sub.25]/[C.sub.15][H.sub.31] ([C.sub.12][N.sub.15])) were synthesized and characterized and [.sup.13]C NMR, IR, Raman spectroscopy, and high resolution mass spectrometry). Their organized smectic phases were investigated by TGA, DSC, powder XRD, and polarized light optical microscopy, and the solids are found to have crystalline and amorphous domains. No evidence for Au... Au interactions was observed. The steady state and time-resolved absorption and emission properties at 298 and 77 K were examined, and surprisingly, the excited lifetime of the triplet excited state in the solid state is extremely short-lived ( Key words: gold complexes, gold nanoparticles, photochemistry, photophysics, mesogens. Nous avons synthétisé cinq nouveaux complexes d'or de formule 4RO[C.sub.6][H.sub.4]C = CAuN=C[C.sub.6][H.sub.4]-4OR (/) (R/R' = C[H.sub.3]/[C.sub.9][H.sub.19] ([C.sub.1][N.sub.9]), [C.sub.15][H.sub.31]/[C.sub.9][H.sub.19] ([C.sub.15][N.sub.9]), [C.sub.6][H.sub.13]/[C.sub.15][H.sub.31] ([C.sub.6][N.sub.15]), [C.sub.9][H.sub.19]/[C.sub.15][H.sub.31] ([C.sub.9][N.sub.15]) et [C.sub.12][H.sub.25]/[C.sub.15][H.sub.31] ([C.sub.12][N.sub.15])) que nous avons caractérisés par spectroscopic RMN [H.sub.1]/[C.sub.13], IR et Raman et par spectrométrie de masse à haute résolution. Nous avons étudié leurs phases smectiques organisées par analyse thermogravimétrique (ATG), calorimétrie différentielle à balayage (DSC), diffraction des rayons X (DRX) sur poudre et micro s copie optique en lumière polarisée, pour en déduire que le solide comporte des domaines cristallins et amorphes. Aucun signe de la présence d'interactions Au... Au n'a été observé. Nous avons examiné leurs propriétés d'absorption et d'émission à l'état d'équilibre et à résolution temporelle à 298 K et à 77 K et, étonnamment, la durée de vie de l'état triplet excité à l'état solide est extrêmement courte ( Mots-clés : complexes d'or, nanoparticules d'or, photochimie, photophysique, mésogènes., Introduction Since the early report of the organometallic ([[êta].sup.1]-ethynyl)-gold(I)-isocyanide synthon, [Au], in 1962, (1) the design of materials based on this motif has been the topic of a long-standing interest. [...]

Plants and photosynthetic bacteria obtain their energy from sunlight or surrounding radiation. Their photosynthetic membranes are composed of a much elaborated series of antenna molecules based on chlorophylls or bacteriochlorophylls, carotenoids playing multiple roles, various electron transport accessories, and central special pairs. The latter components are the most difficult to mimic with exactitude because the structure-property relationship depends on many factors including interplanar distance, slip angle, substituents, metal, and axial ligand. To this list of factors to control with quasi-perfection, one should also add the thermal activation (i.e., temperature). Over the past 15 years or so (2001-2013), an intensive collaboration with Professor Roger Guilard (Universite de Bourgogne, Dijon) dealt with elucidating the role of each parameter to provide the best design of artificial special pairs capable of responding or behaving like the natural special pairs, namely with regards with the antenna effect. The latest feature is one of the defence mechanisms slowing down the rate for the primary electron transfer from the special pair to the electron transport accessories. This review highlights the advances in this challenging area of mimicry of the photophysical events in biological systems, namely the artificial special pairs designed in our laboratory for the antenna processes. Key words: chlorophyll, porphyrin, energy transfer, excitation energy migration, Forster fluorescence energy transfer, special pair, fluorescence, phosphorescence, transient absorption spectroscopy. Resume: Les vegetaux et les bacteries photosynthetiques puisent leur energie dans la lumiere du soleil ou les rayonnements environnants. Leurs membranes photosynthetiques sont composees d'une serie complexe d'antennes, systemes molecules formes de chlorophylles ou bacteriochlorophylles, de carotenoides aux roles multiples, de divers dispositifs de transport electronique et de paries centrales speciales. Ces derniers composants sont les plus difficiles a reproduire avec precision car la relation entre structure et propriete depend de nombreux facteurs parmi lesquels la distance interplanaire, l'angle de glissement, les substituants, le metal et le ligand axial. A cette liste de facteurs a controler avec quasi-perfection, il faut ajouter l'activation thermique (c.-a-d. la temperature). Au cours des 12 dernieres annees (plus exactement entre 2001 et 2013), une collaboration active avec le professeur Roger Guilard (de l'Universite de Bourgogne, a Dijon) a eu pour objectif d'elucider le role de chacun des parametres afin de concevoir, de facon optimale, des paires speciales artificielles capables de reagir ou de se comporter comme les paires speciales naturelles, notamment en ce qui concerne l'effet produit par les antennes. La derniere caracteristique est l'un des mecanismes de defense qui diminue le taux du transfert electronique primaire de la paire speciale vers les dispositifs de transport electronique. La presente etude les avancees realisees dans le domaine de la reproduction des phenomenes photophysiques presents dans les systemes biologiques, en particulier la conception, dans notre laboratoire, de paires speciales artificielles destinees a etre utilisees dans les processus qui ont lieu au niveau des antennes. [Traduit par la Redaction] Mots-cles: chlorophylle, porphyrine, transfert d'energie, migration de l'energie d'excitation, transfert d'energie de fluorescence de type Forster, paire speciale, fluorescence, phosphorescence, spectroscopie d'absorption transitoire., Introduction The special pair plays a central role for the photosynthesis of plants and photosynthetic bacteria. (1) It is located inside a protein called the reaction center surrounded by antenna [...]

The unsaturated redox-active cluster [[[Pd.sub.3][(dppm).sub.3](CO)].sup.n+] (n = 0,1, or 2) reacts with ethylene dicarboxylic esters and a variety of terminal acetylenes (but not PhC ≍ CPh) in all three charge states. In particular, the radical cations [[[[Pd.sub.3][(dppm).sub.3](CO)(RC ≍ CR')]'.sup.??+] can be produced by several routes: one-electron electrochemical reduction of the dication adducts, comproportionation of the neutral and dicationic adducts, as well as the direct complexation of alkyne to the known radical cation [[[Pd.sub.3][(dppm).sub.3](CO)].sup.??+]. Compared with the latter, each of the adducts have significantly extended lifetimes and classify as persistent radicals in solution. The alkyne adducts have been characterized by voltammetry (cyclic and rotating disk electrode), by UV - vis titrations and by MALDI-TOF mass spectra from dithranol matrices. Isotropic solution EPR spectra of the adducts with R = R'= MeOC(O) and EtOC(O), as well as those with R'= H and R = [C.sub.6][H.sub.5], F[C.sub.6][H.sub.4], HC ≍ CC6H4, and EtO have been obtained. Full line shape fitting simulations demonstrate that all display coupling to six different [sup.31]P (I = 1/2) and to one to three [sup.106]Pd (I = 5/2) nuclei. The A([sup.31]P) values range from a low of 3.0 x [10.sup.4] to a high of 180.5 x [10.sup.4] [cm.sup.-1]; this variation is caused by changes in the contribution of P s orbitals to the SOMO resulting from structural distortions of the [Pd.sub.3][P.sub.6] core upon alkyne coordination. Key words: electrochemistry, redox state, electron paramagnetic resonance, catalytic model, palladium, bridging phosphine. Le cluster insature [[[Pd.sub.3][(dppm).sub.3](CO)].sup.n+] (n = 0,1, ou 2) reagit, quelle que soit sa charge, sur des derives acetyleniques de formule generale RCCR' comme des di-esters acetyleniques et sur une variete de derives acetyleniques vrais R'CCH mais pas sur PhC ≍ CPh pour conduire aux adduits [[[Pd.sub.3][(dppm).sub.3](CO)(RCCR')].sup.n+] (n = 0,1,2). En particulier les radicaux cations [[[Pd.sub.3][(dppm).sub.3](CO)(RC ≍ CR')].sup.??+] peuvent etre generes par plusieurs voies : soit par reduction mono-electronique de l'adduit dicationique correspondant [[[Pd.sub.3][(dppm).sub.3](CO)(RC ≍ CR'].sup.2+] soit par une reaction d' antidismutation entre l'adduit neutre et l'adduit dicationique et enfin par la complexation directe de l'alcyne sur l'espece monocationique paramagnetique electrogenere [[[Pd.sub.3][(dppm).sub.3](CO)].sup.??+]. Compare a ce dernier, chacun des adduits paramagnetiques obtenus sont beaucoup plus stables et peuvent donc etre plus facilement caracterises en solution. Les differentes methodes mises en oeuvre pour la caracterisation des adduits reposent sur la voltammetrie cyclique et sur electrode tournante, la spectroscopie UV - visible, la spectrometrie de masse (MALDI-TOF) et par analyse RPE, methode pour laquelle des spectres des adduits [[[Pd.sub.3][(dppm).sub.3](CO)(RC ≍ CR')].sup.??+] avec R = R'= MeOC(O) and EtOC(O) d'une part et avec R'= H, R = [C.sub.6][H.sub.5], F[C.sub.6][H.sub.4], HC ≍ C[C.sub.6][H.sub.4] et EtO d'autre part, ont ete obtenus avec une bonne resolution. La simulation des spectres a permis de tirer toutes les constantes de couplage aux six atomes de phosphore [sup.31]P (I = 1/2) et avec un, deux ou trois des atomes de palladium 106Pd (I = 5/2). Pour expliquer la variation importante des differentes valeurs des constantes A([sup.31]P) qui correspond a 3.0 x [10.sup.4] pour la valeur la plus faible a 180.5 x [10.sup.4] [cm.sup.-1] pour celle la plus elevee, un changement de la contribution de l'orbitale s du phosphore a l'orbitale SOMO, est retenue qui resulte d'une distorsion structurale du coeur [Pd.sub.3][P.sub.6] par coordination de l'alcyne. Mots-cles : electrochimie, etat redox, resonance paramagnetique electronique, modele catalytique, palladium, cluster, diphosphine., Introduction Puddephatt and co-workers (1-3) first reported a convenient synthetic route to trifluoracetate and hexafluorophosphate salts of the cyclic tripalladium cluster [[[Pd.sub.3][(dppm).sub.3]([μ.sub.3]-CO)].sup.2+] in which each diphenylphosphinomethane (dppm) ligand bridges two [...]

Electrochemical methods are used to study the reactivity of the cluster [[[Pd.sub.3][(dppm).sub.3]([[mu].sup.3]-CO)].sup.n+], ([[[Pd.sub.3].sup.n+], n = 2, 1, ) with the low-valent metal-metal-bonded [Pd.sub.2][(dppm).sub.2][Cl.sub.2] dimer ([Pd.sub.2][Cl.sub.2]). The nature of the species formed from [Pd.sub.2][Cl.sub.2] can be regulated by changing the state of charge of the title cluster.

The synthesis and characterization of a new series of relatively flexible cofacial donor-acceptor dyads for singlet-singlet energy transfer with the corrole or etio-porphyrin free base and zinc porphyrin is described, as the acceptor and donor. The results show that the presence of a bulky group located between the acceptor and the donor moiety influences the energy transfer rate.

[[[Pd.sub.3][(dppm).sub.3](CO)].sup.2+], [[[Pd.sub.3]].sup.2+], reacts with N[O.sub.3.sup.-] to form the host-guest adduct [[[Pd.sub.3][(dppm).sub.3] (CO)(N[O.sub.3])].sup.+], [[[Pd.sub.3](N[O.sub.3])].sup.+]. The presence of N[O.sub.3.sup.-] inside the cavity is confirmed by X-ray crystallography. Using a qualitative relationship between [λ.sub.max] (UV-vis) and the association constant of various adducts, the relative binding between N[O.sub.3.sup.-] and [[[Pd.sub.3]].sup.2+] is in the same order of magnitude of that between C[F.sub.3]C[O.sub.2] and [[[Pd.sub.3]].sup.2+]. Based on Pd ... O distances, the N[O.sub.3.sup.-] ion is relativity more weakly associated to [[[Pd.sub.3]].sup.2+] in comparison with the known [[[Pd.sub.3](C[F.sub.3]C[O.sub.2])].sup.+]. Using variation of [N[O.sub.3.sup.-]] in the presence of [[Pd.sub.3]][(P[F.sub.6]).sub.2] and variation of scan rates, the resulting cyclic voltammogramms (CV) were simulated to extract both kinetic and thermodynamic constants associated to a square scheme. Both the anodic and cathodic scans of the title cluster exhibits ECE mechanisms (E = electrochemical process; C = chemical process). For the anodic scan, the EEC event is not ruled out, at least as a minor process. Key words: nitrate, palladium cluster, adduct, electrochemistry, X-ray structure, rate constant, equilibrium constant. Le [[[Pd.sub.3][(dppm).sub.3](CO)].sup.2+], [[[Pd.sub.3]].sup.2+] reagit avec l'anion N[O.sub.3.sup.-] pour former l'adduit hote-invite [[[Pd.sub.3][(dppm).sub.3](CO) (N[O.sub.3])].sup.+], [[[Pd.sub.3](N[O.sub.3])].sup.+]. La presence de l'anion N[O.sub.3.sup.-] dans la cavite est confirmee par diffraction des rayons X. Utilisant une relation qualitative entre [λ.sub.max] (UV-vis) et la constante d'association de divers adduits, on a determine que les fixations relatives entre N[O.sub.3.sup.-] et [[[Pd.sub.3]].sup.2+] sont du mame ordre de grandeur que celles entre C[F.sub.3]C[O.sub.2] et [[[Pd.sub.3]].sup.2+]. Sur la base des distances Pd ... O, l'ion N[O.sub.3.sup.-] est associe relativement plus faiblement au [[[Pd.sub.3]].sup.2+] que dans le produit connu [[[Pd.sub.3](C[F.sub.3] C[O.sub.2])].sup.+]. Utilisant une variation de la concentration de N[O.sub.3.sup.-] en presence de [[Pd.sub.3]][(P[F.sub.6]).sub.2] et une variation des vitesses de balayage, on a pu simuler les voltamperogrammes cycliques pour en tirer les constantes cinetiques ainsi que thermodynamiques associees a un schema carre. Les balayages tant anodique que cathodique de l'agregat mentionne dans le titre presentent tous les deux des mecanismes ECE (E = processus electrochimique; C = processus chimique). Pour le balayage anodique, il n'est pas possible d'eliminer la possibilite d'un processus EEC, au moins comme processus mineur. Mots cles: nitrate, agregat de palladium, adduit, electrochimie, determination de structure par diffraction des rayons X, constante de vitesse, constante d'equilibre. [Traduit par la Redaction], Introduction The use of N[O.sub.3.sup.-] in electrosynthesis is well-known (1-3) and involves the electrochemical one-electron oxidation to generate the highly reactive intermediate N[O.sub.3.sup.*] via the reaction, N[O.sub.3.sup.-] → N[O.sub.3.sup.*] + [...]

The synthesis of bisporphyrins and estimation of the efficient surface of the chromophores for O(sub 2) interactions are presented. It is concluded that there is a diffusion mechanism of O(sub 2) towards the chromophore contrasting with a static mechanism and it is possible for the preparation of effective O(sub 2) sensing porphyrins at an extreme price.

A study was carried out on the free base and biszinc(II) complexes of 5,17-bis[5(2,8,13,28-tetramethy-porphyrin0]-25,26,27,28-tetrapropoxycalix[4]arene that was obtained in four and five steps respectively. Details of the photophysical data and variable-temperature (super 1)H NMR that shows an open geometry of the two porphyrin macrocyles at 298 K are discussed.

The strong Lewis acid tungsten oxo complex of calix[4]arene can be obtained in both hydrated and nonhydrated forms. This complex coordinates a water molecule inside the cavity via strong O ... W interactions with relatively short distances of 2.284(4) and 2.329(2) [Angstrom] for the tungsten oxo complex of calix[4]arene*[H.sub.2]O *aniline (1), and the tungsten oxo complex of calix[4]arene*[H.sub.2]O *toluene (2*toluene), respectively. The strong interactions are also deduced by the relatively high [H.sub.2]O elimination temperature observed by TGA and DSC (above 200 [degrees]C). The coordinated water molecule inside the calix[4]arene cavity is characterized by a strong IR absorption at 3616 [cm.sup.-1], and a narrow resonance at ~1.2 ppm (the chemical shifts of the uncoordinated water are 1.55 and 1.60 ppm in [C.sub.6][D.sub.6] and CD[Cl.sub.3], respectively). This water molecule gives rise to H-bonds with aniline in 1. The tungsten oxo complex of 5,11,17,23-tetrabromocalix[4]arene (4), also binds [H.sub.2]O as the characteristic signatures are observed. The successful removal of [H.sub.2]O in 2, is performed under mild conditions using bis(tetrahydrofuran)-uranyl nitrate as a competitive Lewis acid. When this reaction is performed in acetonitrile, butyronitrile or tert-butylnitrile, the corresponding tungsten oxo complexes of calix[4]arene*acetonitrile (3), *butyronitrile (5), and *tert-butylnitrile (6) are obtained. The use of uranyl as a [H.sub.2]O abstractor is unprecedented. The X-ray structure of 3 consists of a tungsten oxo complex of calix[4]arene coordinated by an acetonitrile molecule (d(W ... N = 2.412(2) [Angstrom]). The tetra-5,11,17, 23-choromethyl-25,26,27,28-tetrahydroxycalix[4]arene reacts with M(O) [Cl.sub.4] (M = Mo, W) in a 1:1 stoichiometry, via a tetra Friedel--Crafts addition of benzene or toluene, followed by a lower-rim complexation of the metal oxide, to form "flower-shaped" calix[4]arenes. This "one pot" double functionalization is unprecedented. Key words: calix[4]arene, tungsten, molybdenum, X-ray, host-guest, Friedel--Crafts, Lewis acid, uranyl, DSC, TGA.

The 5,11- and 5,17-diisocyano-25,26,27,28-tetra-n-propoxycalix[4]arene bridging ligands [(calix(NC).sub.2]) have been prepared in four steps with 34 and 30% global yields, respectively. Their corresponding Ag(I) complexes have been prepared from the direct reaction of the ligand with AgB[F.sub.4] and are characterized from various spectroscopic and physical techniques. The MALDI-TOF spectra indicate the presence of polymers or oligomers of the type {Ag(calix[(NC).sub.2])(B[F.sub.4])}n. The compounds have been characterized further from TGA, DSC, and XRD and compared with the oligomeric species 5,11,17,23-tetraisocyano-25,26, 27,28-tetra-n-propoxycalix[4]arene silver(I) (as a B[F.sup.-.sub.4] salt). Key words: silver, calix[4]arene, polymer, isocyanide, photosensitive, thermal gravimetric analysis.

Research has been conducted on the dicationic palladium cluster Pd (sub)3 (dppm) (sub)3 (CO) (super)2+, where dppm is bis(diphenylphosphino)methane. The reaction of this cluster with acid chlorides performed to afford chloride adduct Pd (sub)3 (dppm) (sub)3 (CO)(Cl) (super)+ and acyl cation as organic counterpart is described.

Research has been conducted on the {Ag(dmb) (sub)2 (super)+} (sub)n oligomers (dmb= 1,8-diisocyano-p-methane). The optical and photophysical properties of these materials and their oligomeric nature in solution have been investigated and the details are presented.

Research has been conducted on the Pd (sub)3 (dppm) (sub)3 (CO)(I) (super)+ cluster. The reduction mechanism of this cluster has been studied via the use of cyclic voltammetry, coulometry and rotating disk electrode and the results indicate that the mechanism depends on the halide and the solvents.

Research has been conducted on the platinum-cobalt carbonyl clusters. The synthesis and characterization of these clusters carried out via the use of IR, (super)31 P{(super)1 H} NMR spectroscopy and X-ray diffraction and the details are reported.

Research has been conducted on the macrocyclic molecule calix[4]arene. The preparation of the mono- and tetraisocyanocalix[4]arene and their gold(II) chloride complexes is reported.

The regioselective upper-rim functionalization of calix[4]arene have been performed to prepare all the multisubstituted diphenylphosphine derivatives. In addition, the X-ray structures of 5,17-dibromo-11, 23-bis(diphenylphosphino)-25,26,27,28-tetra-n-propoxycalix[4]arene and 5,11,17,23-tetrakis(diphenylphosphino)-25,26,27,28-tetra-i-propoxy -calix[4]arene have been determined. Regioselective functionalizations have been achieved using methods that involve appropriate choices of bases, alkyllithium--solvent systems, stoichiometry, and reaction times. A new and convenient method for selectively preparing derivitized calix[4]arenes at proximal positions in relative large scale quantity has been developed and involves a transesterification of the distal diester derivative into the proximal isomer. Key words: calix[4]arenes, phosphine, upper-rim, X-ray structure, transesterification.

Research describes synthesis of a new series of heterobimetallic cofacial diporphyrins containing luminescent Ga(III) centers. The reduction of dioxygen by cofacial cobalt(II) diporphyrins is studied by photophysical and spectroscopic methods.

[sup.1]H NMR, vibrational, and UV-vis spectroscopic measurements for [Pd.sub.2][(dppm).sub.2][Cl.sub.2] (dppm = [Ph.sub.2]PC[H.sub.2]P [Ph.sub.2]), [[Pd.sub.4][(dppm).sub.4][(X).sub.2]][(B[F.sub.4]).sub.2] (X = Cl, H), and [[Pd.sub.4][(dmpm).sub.4][(H).sub.2]][(Br).sub.2] (dmpm = [Me.sub.2]PC[H.sub.2]P[Me.sub.2]) were performed to address the structure of the recently identified title cluster. Its dmpm analogue was prepared from the reaction between [Pd.sub.2] [(dmpm).sub.2][Br.sub.2] and NaB[H.sub.4] in methanol under inert atmosphere, and exhibits the expected nonet (rel. int. 1:8:28:56:70:56:28:8:1) at -5.21 ppm (in [(C[D.sub.3]).sub.2]CO), contrasting with that of [Pd.sub.4][(dppm).sub.4][(H).sup.2+.sub.2] ([delta] + 5.15 ppm, [(C[D.sub.3]).sub.2]CO). This significant difference is explained by the presence of the PdH residues in the deshielding region of the dppm-phenyl groups. The vibrational spectra in the low-frequency region are consistent with a centrosymmetric structure, and a scattering at 144 [cm.sup.-1] in the FT-Raman spectra is observed; a peak that is assigned to v([Pd.sub.2]) on the basis of a comparison with the well established [M.sub.2]-bonded [Pd.sub.2] [(dppm).sub.2][Cl.sub.2] data (([Pd.sub.2]) = 149 [cm.sup.-1]). On the basis of the qualitative temperature behavior of the band maxima and width, the two lowest energy absorption bands in the UV-vis spectra are assigned to d[sigma] [vector] d [sigma]* type transition. EHMO computations predict four well-isolated frontier MO levels, defined as d[sigma]*([Pd.sub.2])/d[sigma]*(PdH) (LUMO + 1), d[sigma]*([Pd.sub.2]) (LUMO), d[sigma]*([Pd.sub.2])/d[sigma]*(PdH) (HOMO), and d[sigma] ([Pd.sub.2]) (HOMO -1), and simple selection rules (u [left and right arrow] g) indicate that only two low-energy electronic transitions are orbitally allowed, consistent with the UV-vis findings. Computer modelings show the presence of large cavities above and under the [Pd.sub.4] plane, described by inner-cavity nonbonded H ... H distances of ~5-8 [Angstrom]. Key. words: cluster, palladium, hydride, structure, spectroscopy.

Research has been conducted on a compound prepared from the Pt (sub)2 (dba) (sub)3 and [Au-(PPh (sub)3) (sub)2](PF (sub)6) reaction. The use of the X-ray crystallography is described.

The synthesis and characterization of the binuclear Ag2(dmb)Y2 complexes, where dmb = 1,8-diisocyano-p-methane; Y = NO3-, ClO4-, CH3CO2-, are presented. The synthesis involves the direct reactions of the AgY salts with dmb in a 1:1 stoichiometric amount. The results of X-ray crystal analysis showed that the structure of the complex consists of two Ag+ atoms bridged by two dmb ligands forming a 20-membered ring and by two counterions via one of the O-atoms, forming a four-membered ring.

The reactions Pt2(dba)3*CHCl3 + 2dmb + 2PPh3 and Pt2(dba)3*CHCl3 + 2dmb + diphos were observed to produce the unprecedented linear [Pt4(dmb)4(PPh3)2]Cl2 cluster (cluster valence electron count = 58) and the polymeric {[Pt4(dmb)4(diphos)](Cl)2}n materials (MW approximately 203,000 (diphos = dppb), approximately 307,000 (dppp) and approximately 84,000 (dpph)), respectively. These new materials were found to be luminescent at 77 K and were studied through electronic and Raman spectroscopy and EHMO calculation.

Results indicated that the d(super 10)-d(super 10) binuclear copper acetate complex, Cu(sub 2)(dppm)(sub 2)(O(sub 2)CCH(sub 3))(super +) dimer, exhibited luminescence at 77 K and dissociated in solution to form the bicoordinated and luminescent Cu(sub 2)(dppm)(O(sub 2)CCH(sub 3))(super +) complex. The dissociation was secondary to the weak Cu-Cu interactions. It was indicated that the emissive states were combined Cu -> phenylphosphine/acetate charge transfer states.

A series of new organometallic polymers of the type ((M(dmb)2)Y)n (dmb=1,8-diisocyano-p-menthane; Y=BF4-, NO3-, ClO4-, M=Cu; Y=BF4-, PF6-, NO3-, CH3CO2-, ClO40; M=Ag) has been found. These materials were characterized from single-crystal X-ray diffraction, X-ray powder diffraction, differential scanning calorimetry, solid-state magic spinning angle and solution 13C-NMR, and spin-lattice relaxation time measurements.

The lowest energy excited state of the luminescent Cu3(dppm)OH2+ host cluster has been examined. Density functional theory has been employed to obtain the molecular orbital diagram, electronic transitions and the evidence of the Cu...Cu interactions. These were confirmed experimentally by UV-visible, luminescence and polarized luminescence spectroscopy.

The ground and triplet excited state geometries of the complexes Pd2(CN-t-Bu)4Cl2, Pd2(tmb)2Cl2 (tmb = 2,5-dimethyl-2',5'-diisocyanohexane), and Pd3(dppm)3CO2+ (dppm = C6H5 2P 2CH2) are optimized by density functional theory. The ground state structural calculations are highly consistent with the X-ray crystallographic results indicating that in the excited state, the cavity size of Pd3(dppm)3CO2+ increases with Pd-Pd bond length. The increase is on the order of ~0.186 angstroms in the 3A2 excited state.

The structures of two isolated isomers of the phosphido-bridged platinum cluster Pt3(mu-PPH2)3Ph(PPh3)2 showed nearly equilateral 42-electron clusters and varying Pt-Pt distances determined by the number of electrons contributed by the different bridging ligands. Both clusters exhibited the first example of reversible core isomerism brought about by the presence or absence of the Pt-Pt bond. Interconversion of the two isomers can reportedly be done by replacing the crystallization solvent. The distortion of the Pt3 core due to the substition of a phosphine ligand with a better omega-donor ligand resulted to the formation of the two isomers.

X-ray crystallographic, UV-visible spectroscopic and molecular mechanistic studies of ground-state guest-host chemistry in the cavity of Pd3(dppm)3CO2+ cluster show the influence of substrate charge, ligand strength, substrate size and its hydrophobic properties on the strength of binding between substrate and bifunctional cavity. Benesi-Hildebrand, Scatchard and Scott techniques help estimate the binding constants for 20 substrates.

Nanosecond and picosecond flash photolysis spectroscopy and determination of emission lifetimes prove the excited-state interaction between clusters and the organic substrates in the cavity of unsaturated cyclic trinuclear clusters M3(dppm)3 CO2+. Moment band analysis of transitions helps determine the cavity sizes in the excited state and M-M distance is between 3.1 and 3.3 angstroms, in the excited state.

Theoretical and experimental studies are conducted on the characteristics of PdI-PdI bonds and the lowest energy excited states of Pd2(dmb)2X2 complexes (dmb = 1,8-diisocyano-p-menthane, X = Cl, Br). Unlike the usual 'almost pure' dz2 M2 interactions in the prototype M-M sigma-bonded compound M2(CO)10, M2 sigma-bonding interactions emerge primarily from interactions between dz2 and dx2-y2 orbitals, as is evident from extended Huckel molecular orbital calculations.

The X-ray diffraction structures of three Ag2(dmb)2X2 (X = Cl, Br, I) complexes and of the cis-Pd(CNC(CH3)3)2Cl2 complex were reported. The low-frequency solid-state vibrational spectra of these compounds and of four other related complexes containing Ag-Ag and Pd-Pd units were also reported. Using literature data for other M2 compounds, reparametrized Herschbach-Laurie type relationships applied to silver and palladium systems were designed.

Flash photolysis and emission spectroscopy measurements were conducted on cyclic unsaturated M3(dppm)3CO2+ clusters wherein M represented palladium or platinum atoms. Results indicated that solvent media and substrate interactions influenced the observed band shapes and adsorptivities for the bands. In addition, the excited-state chemistry, quantumyields and temperature measurements as a factor of luminescence were also derived.

A flash photolysis investigation of the complexes M2(dba)3, where M = Pd or Pt, is undertaken. The kinetics of the transient and excited-state deactivation of the complexes are also presented. The study is extended to include the photophysics of the free ligands dba, bis(2-methylbenzylidene)acetone and bis(2-methoxybenzylidene)acetone. Moreover, the lifetimes for triplet excited states and geometric isomers are also reported.

The Pd2(diiso)2X2 complexes, where diiso = dmb (1, 8-diisocyano-para-menthane) and tmb 2,5-dimethyl-2,5-diisocyanohexane and X = Cl and Br, were obtained from the reaction of Pd2(dba)3, where dba = dibenzylideneacetone, with Pd2(diiso)2X4 and diisocyanide bridging ligand. These complexes are air-stable, with structures expected to contain distortions. The Pd2 bond length in d9-d9 species range from 2.6 to 2.7 Angstrom. Molecular distortions are observed as a result of the dmb ligand accommodating a large change in bite distance. No isosbestic points were recorded during the photoreactions.

The absorption and emission spectra of the diimine dithiolate complexes of platinum(II) were investigated. The strong solvatochromic absorption band exhibited by all the complexes containing unsaturated and saturated dithiolates and by the bis(thiolate) complexes indicate that the lowest unoccupied molecular orbital of these complexes is pi*(diimine). The presence of the same solvatochromic transition in complexes with nonchelating thiolate ligands further supports this assignment. The broad asymmetric emission of all the complexes except those of mnt arises from 3(d Pt/p S -pi* diimine).

The two silver and gold dimers, Ag2(bis dimethylphosphino methane) (dmpm)2Br2 and (Au2 dmpm 2)(PF6)2, that have been prepared contain Ag2/Au2(dmpm)(sub 2)(super 2+) core structures with a ligand-bridged pair of metal atoms. The Ag2 compound features an eight-membered ring structure with an intra- and intermolecular r(Ag2) values of 3.605 and 3.916 angstroms, respectively, while the Au2 ring compound adopts a chair conformation with r(Au2) of 3.045 angstroms. Additionally, force constants, metal-metal separation and other measurements are determined using X-ray diffraction, far-infrared and Raman spectroscopic analyses.

Measurement of Rh2-stretching frequencies from complexes of known metal-metal separations, along with literature data, enable the derivation of Herschbach and Laurie type (H-L) relations for Rh2 systems. Raman spectroscopic measurements enable the determination of Rh2 force constants. Rh2-stretching frequency facilitates the determination of metal-metal separations and the uncertainty is for -0.05 angstroms.

The synthesis of conjugated rigid rod and nonconjugated flexible polymers and corresponding model compounds bearing the d(super 9)-d(super 9) M(sub 2)(dppm)(sub 2)(super 2+) fragments (where dppm=bis(diphenylphosphino)methane) is reported. The presence of pi-delocalization between the M(sub 2)(dppm)(sub 2) fragments is addressed using the comparison between aryl- and alkyl-diisocyanide assembling ligands.

Syntheses and characterization of the Pd2-bonded organometallic polymers of the type{[Pd2-(dmb)(sub 2)(diphos)](ClO4)(sub 2)} with diphos = dppb, dpppen, dpph, and dpa is discussed. The strategy to use metallic fragments that are only functionalizable at the axial positions in order to synthesize polymeric or oligomeric materials is presented.

The mixed-ligand polymers {[M(diphos)(CN-t-Bu)2]BF4}n (M = Cu, Ag; diphos = dppm, dppb, dpppen, dpph) and {[M(diphos)(dmb)]BF4}n(dmb = 1,8-diisocyano-p-menthane) are synthesized and characterized. TGA, DSC, XRD, and solid-state luminescence spectra and emission lifetimes are reported.

The tile bridging ligand has become an increasingly versatile building block over the past thirty years. A new strategy to synthesize organometallic oligomers is presented, which consists of using the title disocyanide and chelated metal fragments with bis(diphenylphosphine)alkanes.