Trinuclear Derivatives Research Articles

Synthesis and Characterisation of Some New Mono- and Trinuclear Mixed-Ligand Derivatives of Aluminium

Synthesis and Characterisation of Some New Mono- and Trinuclear Mixed-Ligand Derivatives of Aluminium

Reactivity of Alkynes Containing α‐Hydrogen Atoms with a Triruthenium Hydrido Carbonyl Cluster: Alkenyl versus Allyl Cluster Derivatives

The reactions of the hydrido-triruthenium cluster complex [Ru3(mu-H)(mu3-kappa(2)-HNNMe2)(CO)9] (1; H2NNMe2 = 1,1-dimethylhydrazine) with alkynes that have alpha-hydrogen atoms give trinuclear derivatives containing edge-bridging allyl or face-capping alkenyl ligands. Under mild conditions (THF, 70 degrees C) the isolated products are as follows: [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-1-syn-Me-3-anti-EtC3H3)(mu-CO)2(CO)6] (2) and [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-1-syn-Me-3-syn-EtC3H3)(mu-CO)2(CO)6] (3) from 3-hexyne; [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-3-anti-PhC3H4)(mu-CO)2(CO)6] (4), [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(2)-MeCCHPh)(mu-CO)2(CO)6] (5) and [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-PhCCHMe)(mu-CO)2(CO)6] (6) from 1-phenyl-1-propyne; [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(2)-3-anti-PrC3H4)(mu-CO)2(CO)6] (7), [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-BuCCH2)(mu-CO)2(CO)6] (8), and [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-HCCHBu)(mu-CO)2(CO)6] (9) from 1-hexyne; [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-HOH2CCCH2)(mu-CO)2(CO)6] (10) from propargyl alcohol; and [Ru3(mu3-kappa(2)-HNNMe2)(mu3-kappa(2)-MeOCH2CCH2)(mu-CO)2(CO)6] (11) from 3-methoxy-1-propyne. The regioselectivity of these reactions depends upon the nature of the alkyne reagent, which affects considerably the kinetic barriers of important reaction steps and the stability of the final products. It has been established that the face-capped alkenyl derivatives are not precursors to the allyl products, which are formed via edge-bridged alkenyl intermediates. At higher temperature (toluene, 110 degrees C), the complexes that have allyl ligands with an anti substituent are isomerized into allyl derivatives with that substituent in the syn position, for example, 4 into [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(3)-3-syn-PhC3H4)(mu-CO)2(CO)6] (14). The diene complex [Ru3(mu-H)(mu3-kappa(2)-HNNMe2)(mu-kappa(4)-trans-EtC4H5)(CO)7] (13) has been obtained from the thermolysis of compounds 2 and 7 at 110 degrees C (3 and [Ru3(mu3-kappa(2)-HNNMe2)(mu-kappa(2)-3-syn-PrC3H4)(mu-CO)2(CO)6] (12) are also formed in these reactions). A DFT theoretical study has allowed a comparison of the thermodynamic stabilities of isomeric compounds and has helped rationalize the experimental results. Mechanistic proposals for the synthesis of the allyl complexes and their isomerization processes are also provided.

Electronic interactions in oligoferrocenes with cationic, neutral and anionic four-coordinate boron bridges

Dinuclear and trinuclear ferrocene complexes {[Fc2BMe2]Li, [Fc-BMe2-fc-BMe2-Fc]Li2, Fc2B(pyind), [Fc2B(bipy)]PF6, [Fc-B(bipy)-fc-B(bipy)-Fc](PF6)2} bearing anionic, uncharged, and cationic four-coordinate boron bridges have been synthesized (Fc: ferrocenyl; fc: 1,1'-ferrocenylene; pyind: 5-fluoro-2-(2'-pyridyl)indolyl; bipy: 2,2'-bipyridyl). The molecular structures of [Fc2BMe2]Li(12-crown-4)2, [Fc-BMe2-fc-BMe2-Fc](Li(12-crown-4)2)2, Fc2B(pyind), and [Fc2B(bipy)]PF6 were determined by X-ray crystallography. The anionic aggregates [Fc2BMe2]- and [Fc-BMe2-fc-BMe2-Fc]2- are very sensitive to air and moisture whereas bromide salts of their cationic counterparts [Fc(2)B(bipy)]+ and [Fc-B(bipy)-fc-B(bipy)-Fc]2+ may be dissolved in water without decomposition. Cyclic voltammograms of the diferrocene species show two well-resolved one-electron transitions separated by 0.21 V ([Fc2BMe2]Li; Eo' = -0.43 V, -0.64 V; vs. FcH/FcH+), 0.18 V (Fc2B(pyind); Eo' = -0.03 V, -0.21 V), and 0.16 V ([Fc2B(bipy)]PF6; Eo' = +0.23 V, +0.07 V), which indicates electronic interactions between the two ferrocenyl substituents. Two redox waves with an intensity ratio of 1:2 are observed in the cyclic voltammograms of the trinuclear derivatives [Fc-BMe2-fc-BMe2-Fc]Li2 and [Fc-B(bipy)-fc-B(bipy)-Fc](PF6)2. In the case of the BMe(2)-bridged species, the electrochemically unique central ferrocenylene unit is oxidized at a much more cathodic potential value (Eo' = -1.21 V) than the two terminal ferrocenyl substituents (Eo' = -0.51 V). The opposite is true in the case of the B(bipy)-bridged trimer where oxidation of the terminal ferrocenyl groups (Eo' = +0.03 V) precedes oxidation of the internal iron atom (Eo' = +0.26 V). The Fe(II)/Fe(III) redox potentials of the mono- and dianionic species differ to a much larger extent from the redox potential of parent ferrocene (Eo' = 0 V) than the Eo' values of the corresponding mono- and dicationic derivatives. Apart from electrostatic interactions, the electrochemical properties of BMe2- and B(bipy)-bridged oligoferrocenes are determined by the pronounced positive inductive effect of triorganoborate substituents together with positive sigma/pi* hyperconjugation on the one hand and ferrocene-to-B(bipy) charge transfer on the other.

Cobalt and nickel complexes of a tetradentate phthalazine ligand – mononuclear, dinuclear and trinuclear derivatives

Examples of mononuclear (Ni(II)), dinuclear (Ni(II), Co(III)) and trinuclear (Ni(II)) complexes of the ligand 1,4-di-2 ′-pyridylaminophthalazine (pap) are reported. In the dinuclear complexes two metal ions are bridged by phthalazine (N–N) groups and two water molecules (Ni(II)), and two hydroxide ions (Co(III)). A novel Ni 3(μ 3-OH) 2 central core exists in the trinuclear example, with additional phthalazine (N–N) bridges linking the Ni(II) centers. The polynuclear nickel complexes exhibit antiferromagnetic exchange through combinations of diazine (N–N) and water and hydroxide bridges ( J(Ni 2)=−4.9, −5.25 cm −1; J(Ni 3)=−15.7 cm −1). The Co(III) complex is diamagnetic.

Synthesis, structures and photophysics of novel luminescent platinum–copper complexes

The novel hexanuclear platinum–copper complex [Pt 2Cu 4(C 6F 5) 4(CC t Bu) 4(acetone) 2] ( 1) and the polynuclear derivative [PtCu 2(C 6F 5) 2(CCPh) 2] x ( 2), which crystallises in acetone as [Pt 2Cu 4(C 6F 5) 4(CCPh) 4(acetone) 4] ( 2) ·(acetone) 4, have been prepared using [ cis-Pt(C 6F 5) 2(THF) 2] and the corresponding copper–acetylide [Cu(CCR)] x (molar ratio 1:2) as starting materials. Treatment of 1 and 2 with 2,2′-bipyridine (molar ratio Cu–bipy 1:1), afforded the new trinuclear derivatives [{ cis-Pt(C 6F 5) 2(μ-CCR) 2}{Cu(bipy)} 2] (R= t Bu 3, Ph 4), in which the dianionic 3-platina-1,4-diyne acts as a didentate bridging ligand to two different cationic Cu(bipy) units through η 2-side-on coordination of the alkynyl fragments. While similar treatment of 1 with dppe (Cu–dppe 1:1) yielded [{ cis-Pt(C 6F 5) 2(μ-CC t Bu) 2}{Cu(dppe)} 2] ( 5), the analogous reaction of 2 with dppe afforded a mixture of complexes containing [Pt(C 6F 5)(CCPh)(dppe)] as the main platinum compound. The crystal structures of 1, 2·(acetone) 4, 3 and 4 and the luminescent behaviour of all complexes have been determined. A comparison of the photoluminescent spectra of 1 and 2 with those of the related platinum–silver species [PtAg 2(C 6F 5) 2(CCR) 2] x and the monomeric [ cis-Pt(C 6F 5) 2(CCR) 2] 2− suggests the presence of emitting states bearing a large cluster [PtM 2] x -to-ligand (alkynide) charge transfer (CLCT).

Beryllium(II) complexes of the Kläui tripodal ligand cyclopentadienyltris(diethylphosphito-p)cobaltate(-).

The interactions of the beryllium(II) ion with the cyclopentadienyltris(diethylphosphito-P)cobaltate monoanion, L(-), have been investigated, in aqueous solution, by synthetic methods, potentiometry, ESMS, and (1)H, (31)P, and (9)Be NMR spectroscopy. L(-) has been found able to displace either two or three water molecules in the beryllium(II) coordination sphere, to form mononuclear, dinuclear, and trinuclear derivatives, in which the metal ion is pseudotetrahedrally coordinated. The species [BeL(H(2)O)](+) and [Be(2)L(2)(mu-OH)](+) have been identified in solution while complexes of formula BeL(2) and [Be(3)L(4)](ClO(4))(2) have been isolated as solid materials. The species [BeL(OPPh(2))](+), closely related to [BeL(H(2)O)](+), has been characterized in acetone solution and isolated as tetraphenylborate salt. The structure of the unusual trimeric complex [Be(3)L(4)](2+) has been elucidated by an unprecedented 2D (9)Be-(31)P NMR correlation spectrum showing the presence of a single central beryllium nucleus and two equivalent terminal beryllium nuclei. The three beryllium centers are held together by four cobaltate ligands, which display two different bonding modes: two ligands are terminally linked with all the three oxygen donors to one terminal beryllium, and the other two bridge two metal centers, sharing the oxygen donors between central and terminal beryllium atoms.

Copper(II) adducts with N, N, N′, N′-tetramethylethane-1,2-diamine and attempts to prepare trinuclear derivatives

We have attempted to prepare complexes of the type [M 3Cl 5(tmen) 3][BPh 4] (tmen=Me 2N(CH 2) 2NMe 2) with M=Cu. Such species are already known for M=Ti, V, Fe, Ni, and Co, but we have been unable to prepare any Cu analogues. The [BPh 4] − appears to reduce Cu II to Cu I and we isolated the known [Cu(tmen) 2][CuCl 2] from reaction mixtures that contained it. Attempts to obviate this reduction by using a different anion were successful, but no triangulo species were isolated. However, during this work we isolated and structurally characterised [{CuF(BF 4)(tmen)} 2] and [{Cu(OH)((BF 4)(tmen)} 2].

New conducting co-ordination polymers containing M(dmit)2 links

The reaction of [M(dmit)(P-P)] (P-P = dppm, dppe) (dmit = 1,3-dithiol-2-thione-4,5-dimercapto, dppe = bis-(diphenylphosphine)ethane, dppm = bis-(diphenylphosphine)methane) with gold, silver and copper salts provides trinuclear derivatives with the general formula [M'{M(dmit)(P-P)} 2 ] (M = Ni, Pd; M' = Cu, Ag, Au). The same type of reactions starting with [M(dmit) 2 ] n- (M = Ni, Au) gave conducting polymers with different stoichiometry depending on the metal and the reaction conditions.

Reactivity of Diynes with a 1-Azavinylidene-Bridged Triruthenium Carbonyl Cluster. Insertion Reactions of Diynes into Ru−H, Ru−C, and Ru−N Bonds

The reactivity of the 1-azavinylidene cluster complex [Ru3(μ-H)(μ-NCPh2)(CO)10] (1) with diynes has been studied. The nonconjugated diyne 1-trimethylsilyl-1,4-pentadiyne affords the binuclear ynenyl derivative [Ru2(μ-NCPh2)(μ-η2-CH2CCH2C⋮CSiMe3)(CO)6] (2), which results from cluster fragmentation and from the insertion of the terminal alkyne fragment of the diyne into a Ru−H bond. The reactions of 1 with the internal conjugated diynes 1,6-diphenoxy-2,4-hexadiyne, 2,4-hexadiyne, and diphenylbutadiyne have allowed the isolation of the trinuclear derivatives [Ru3{μ-η2-NCPh(C6H4)}(μ3-η4-PhOCH2CHCCCHCH2OPh)(CO)8] (3), [Ru3{μ3-η4-NCPh(C6H4)CH(Me)CHCCMe}(CO)9] (4), [Ru3{μ-η2-NCPh(C6H4)}(μ3-η4-PhCHCHC⋮CPh)(CO)8] (5), and [Ru3{μ3-η4-PhCHCHC(CPh)NCPh(C6H4)}(CO)9] (6). The four compounds have been characterized by X-ray diffraction methods. They all arise from the orthometalation of a phenyl ring of the 1-azavinylidene ligand and from the transfer of two hydride ligands (the original plus that coming from the orthometalation) to the coordinated diyne. This hydrogenation process can proceed as a 1,4-addition to give a 1,2,3-triene fragment (as occurs in 3) or as a 1,2-addition to give an enyne fragment (as occurs in 5). In the cases of 4 and 6, a 1,2-addition of hydrogen is accompanied by the insertion of the unsaturated hydrocarbon fragment into the Ru−C bond associated with the orthometalated ring (4, 6) and into a Ru−N bond (6). The precise order by which these processes lead to the corresponding products has not been established. The reactions involved in the formation of compounds 2−6 represent excellent examples of insertion of diynes into M−H, M−C, and M−N bonds of metal clusters and have allowed the characterization of substituted 1-yn-3-enyl (in 2), 1,2,3-triene (in 3), 1,2-dienyl (in 4), 1-en-3-yne (in 5), and 2-(N-imido)-1,2,3-allyl-1-yl (in 6) ligands.

Pt(C⋮CR)4]2- as Double Alkynylation Reagents: Facile Formation of Binuclear Bis(μ-alkynide) (M−Pt) and Unsymmetrical Trinuclear Double Bis(μ-alkynide) (M−Pt−Pt) Complexes

Treatment of (NBu4)2[Pt(C⋮CR)4]·2H2O (R = t-Bu, 1a; SiMe3, 1b; Ph, 1c) with 1 equiv of the dicationic solvento species [Cp*M(PEt3)(acetone)2](ClO4)2 (M = Rh, Ir) results in double alkynyl transfer to give the binuclear compounds [(PEt3)Cp*M(μ-1κCα:η2-C⋮CR)2Pt(C⋮CR)2] (M = Rh, 2; Ir, 3), in which the organometallic unit “cis-Pt(C⋮CR)2” is unusually stabilized by η2-bis(alkyne) interactions, as has also been confirmed for the related binuclear complex [(PPh3)Cp*Rh(μ-1κCα:η2-C⋮CSiMe3)2Pt(C⋮CSiMe3)2], 4b, which has been prepared analogously. These binuclear tetraalkynyl complexes can be used as precursors to unusual bis(double-alkynide)-bridged trinuclear derivatives [(PEt3)Cp*M(μ-1κCα:η2-C⋮CR)2Pt(μ-2κCα:η2-C⋮CR)2Pt(C6F5)2] (M = Rh, 5; Ir, 6) by displacement reactions of thf from [cis-Pt(C6F5)2(thf)2]. An X-ray diffraction study confirms that in complex 5b (R = SiMe3) the mononuclear rhodium fragment “Cp*Rh(C⋮CSiMe3)2(PEt3)” acts as a chelating bidentate ligand toward the alkynyl-bridged diplatinum organometallic unit Pt(μ-1κCα:η2-C⋮CSiMe)2Pt(C6F5)2.

Dithiocarbamate Ligands as Building-Blocks in the Coordination Chemistry of Gold.

The monodentate dithiocarbamate complexes [Au(2)(S(2)CNR(2))(2){&mgr;-(PPh(2))(2)C=CH(2)}] (R = Me (1), Et (2), Bz (3)) are obtained by reaction of [Au(2)Cl(2){&mgr;-(PPh(2))(2)C=CH(2)}] with NaS(2)CNR(2). The free sulfur atoms in complex 2 can subsequently be used to coordinate a third metal center, giving the trinuclear derivatives [Au(2)M(&mgr;-S(2)CNEt(2))(2){&mgr;-(PPh(2))(2)C=CH(2)}]X (X = ClO(4), M = Au (5), Ag (6); X = PF(6), M = Cu (7)). The dinuclear tricoordinate gold(I) complexes [Au(2)(&mgr;-S(2)CNEt(2)){&mgr;-(PPh(2))(2)C=CH(2)}(2)]ClO(4) (8) and [Au(2)(&mgr;-S(2)CNEt(2)){&mgr;-(PPh(2))(2)C=CH(2)}(PPh(3))(2)]ClO(4) (9) are obtained by reaction of [Au(2)(&mgr;-S(2)CNEt(2)){&mgr;-(PPh(2))(2)C=CH(2)}]ClO(4) (4) with (PPh(2))(2)C=CH(2) or PPh(3). The former is also obtained by reaction of [Au(2){&mgr;-(PPh(2))(2)C=CH(2)}(2)](ClO(4))(2) with sodium N,N-diethyldithiocarbamate (1:1). The crystal structures of complexes 2 and 8 are established by X-ray crystallography.

Chemistry of Palladium and Platinum with Selenium and Tellurium Ligands

Reactions of NaER (E = Se, Te; R = Ph, substituted Ph or 2-pyridyl) with a number of mono- and bi-nuclear palladium and platinum complexes have been investigated. Complexes of the type [M(Sepy)2], [M(ER)2(PR3)2], [M2Cl2(μ-ER)2(PR3)2] and [M2Cl2(μ-Cl)(μ-ER)(PR3)2] (M = Pd, Pt) were isolated. They were characterized by elemental analysis, NMR (1H, 13C, 31P, 77Se, 125Te, 195Pt) data and in a few cases by X-ray diffraction studies. The [M(Sepy)2(PPh3)2] dissociates into PPh3 and [M(Sepy)(η2-Sepy)(PPh3)] in solution. 2-Selenopyridine in its complexes acts in a monodentate (bonding through selenium) as well as in chelating (Se⌢N) or bridging fashion. The mononuclear complexes [M(ER)2(PR3)2] are useful precursors for stepwise synthesis of cationic bi- and tri-nuclear derivatives.

Chemistry of Palladium and Platinum with Selenium and Tellurium Ligands

Reactions of NaER (E = Se, Te; R = Ph, substituted Ph or 2-pyridyl) with a number of mono- and bi-nuclear palladium and platinum complexes have been investigated. Complexes of the type [M(Sepy)2], [M(ER)2(PR3)2], [M2Cl2(μ-ER)2(PR3)2] and [M2Cl2(μ-Cl)(μ-ER)(PR3)2] (M = Pd, Pt) were isolated. They were characterized by elemental analysis, NMR (1H, 13C, 31P, 77Se, 125Te, 195Pt) data and in a few cases by X-ray diffraction studies. The [M(Sepy)2(PPh3)2] dissociates into PPh3 and [M(Sepy)(η2-Sepy)(PPh3)] in solution. 2-Selenopyridine in its complexes acts in a monodentate (bonding through selenium) as well as in chelating (Se⌢N) or bridging fashion. The mononuclear complexes [M(ER)2(PR3)2] are useful precursors for stepwise synthesis of cationic bi- and tri-nuclear derivatives.

Polynuclear mesityl-gold and -gold-silver derivatives. Crystal structure of [Ag(μ-dppm) 2{Au(mes)} 2]C1O 4 · 3CH 2Cl 2 (dppm = bis(diphenylphosphino)methane, mes=mesityl)

The reaction of the complex [Au(mes)dppm] (mes = mesityl, dppm = PPH 2CH 2PPh 2) with [Au(tht) 2]SO 3CF 3 (tht = tetrahydrothiophene) or AgClO 4 in molar ratio 2:1 afforded trinuclear derivatives [M(μ-dppm) 2{Au(mes)} 2]A (M = Au, A = SO 3CF 3 ( 1); M = Ag, A = C1O 4 ( 2)). The structure of [Ag(μ-dppm) 2{Au(mes)} 2]ClO 4 has been determined by a single-crystal X-ray diffraction study, which shows AuAg distances of 2.944(2) and 2.946(2) Å.

Trinuclear Au2Ag and Au2Cu Complexes with Mesityl Bridging Ligands. X-ray Structure of the Chain Polymer [{Au(μ-mes)AsPh3}2Ag](ClO4)

The reaction of the complex [Au(mes)L] (mes = mesityl, L = PPh3, AsPh3) with Ag(OSO2CF3), Ag(OClO3), or [Cu(CNMe)4]PF6, in molar ratio 2:1, affords trinuclear derivatives [{Au(μ-mes)L}2M]A [M = Ag, L = PPh3, A = SO3CF3- (1); L = AsPh3, A = ClO4- (2a), SO3CF3- (2b); M = Cu, A = PF6-, L = PPh3 (3), AsPh3 (4)]. Complexes 1 and 2 react further with various ligands in a 1:1 molar ratio to give the dinuclear compounds [AuAg(μ-mes)(PPh3)L]SO3CF3 (L = PPh3, tetrahydrothiophene, 2,2‘-bipyridine, or SPPh3) or [AuAg(μ-mes)(AsPh3)L]A (L = AsPh3, A = SO3CF3-; L = 1/2 Ph2AsCH2AsPh2, A = ClO4-). The structure of [{Au(μ-mes)AsPh3}2Ag](ClO4)(2a) has been determined by a single-crystal X-ray diffraction study, which shows an Au−Ag distance of 2.7758(8) A; the trinuclear species are connected by short Au···Au contacts of 3.132 A to form a chain polymer.

Bis(purine) Complexes oftrans-a2PtII: Preparation and X-ray Structures of Bis(9-methyladenine) and Mixed 9-Methyladenine, 9-Methylguanine Complexes and Chemistry Relevant to Metal-Modified Nucleobase Triples and Quartets

Mononuclear bis(purine) complexes of trans-a2PtII, trans-[(NH3)2Pt(9-MeA-N7) (9-MeGH-N7)](NO3)2·H2O (1b) and trans-[(NH3)2Pt(9-MeA-N7)2](ClO4)2·H2O (3c), have been prepared and their structures determined by X-ray crystallography. 1b: Space group P1, a = 7.245 (5) A, b = 7.715(6) A, c = 10.907(8) A, α = 82.36(6)°, β = 86.62(6)°, γ = 70.15(6)°, V = 568.3(7) A3, Z = 1. 3c: Space group P21/c, a = 8.312(2) A, b = 15.386(3) A, c = 12.365(2) A, β = 94.83(3)°, V = 1575.72(55) A, Z = 2. The cation of 3c is centrosymmetric. In the cation of 1b, the two purines adopt a head−head orientation with an intramolecular H bond of 2.94(3) A between the exocyclic amino group of 9-MeA and the exocyclic carbonyl group of 9-MeGH. Di- and trinuclear derivatives of 1b and 3c have been synthesized and/or studied in solution. They include compounds of types Cl•N1-A-N7•GH (2a), T•N1-A-N7•GH (2b), GH•N1-A-N7•T (2c), and GH•N7-A-N1•N1-A-N7•GH (2d) as well as X•N1-A-N7•N7-A-N1•X (X = Cl (4), GH (5a), T (5b)) with • representing tran...

Coordination chemistry of thioether–pyridazine macrocycles. I. Synthetic, structural, and spectroscopic studies of Cu(II) and Cu(I) complexes of novel thioether–pyridazine macrocycles that contain two or three pyridazine subunits

The preparations of thioether–pyridazine macrocycles containing three (L1) and two (L2) pyridazine subunits and their copper complexes are described. The ligands are characterized by 1H nuclear magnetic resonance and mass spectrometry and in one case by X-ray crystallography, and the complexes by infrared, electronic, and electron spin resonance (esr) spectra and in some cases by X-ray crystallography. The complex [Cu3(L1)2Cl6]•2CHCl3 (1) crystallized in the triclinic system, space group [Formula: see text] with a = 13.661(2) Å, b = 14.174(3) Å, c = 9.412(2) Å, α = 101.08(2)°, β = 96.94(2)°, γ = 75.76(2)°, V = 1728.2(6) Å3, and Z = 2 (R = 0.056, Rw = 0.048 for 2080 reflections). Two monodentate pyridazine rings in each ligand bind to one square-planar copper centre with the third monodentate pyridazine in each ligand linking the two to the central square-planar copper. The complex [Cu(L2)Cl2] (2) crystallized in the orthorhombic system, space group Pnma, with a = 8.571(1) Å, b = 16.104(3) Å, c = 13.961(2) Å, V = 1927(1) Å3, and Z = 4 (R = 0.037, Rw = 0.033 for 1070 reflections). A cis square-planar structure exists for 2 with monodentate pyridazines. [Cu(L2)2]•(ClO4)2•CH3CN•CHCl3 (5) crystallized in the triclinic system, space group [Formula: see text] with a = 12.888(4) Å, b = 17.462(6) Å, c = 10.906(1) Å, α = 96.07(2)°, β = 104.18(2)°, γ = 94.51(2)°, V = 2352(1) Å3, and Z = 2 (R = 0.053, Rw = 0.044 for 2941 reflections). Two ligands involving monodentate pyridazine rings bind to a square-planar copper(II) centre. The protonated ligand salt [L2H](ClO4)•H2O (6) crystallized in the monoclinic system, space group P21/n, with a = 14.762(4) Å, b = 8.637(5) Å, c = 16.267(4) Å, β = 92.78(2)°, V = 2072(1) Å3, and Z = 4 (R = 0.064, Rw = 0.053 for 1456 reflections). No sulfur coordination is observed in these complexes and there is no apparent spin exchange in the trinuclear derivative.

Mono-, di- and trinuclear Pt(II), mononuclear Pt(IV), mixed Pt(II),Pt(IV), mixed Pt(II),Ag(I) complexes of 9-methyladenine (9-MeA), and the X-ray structure of [(dien)Pt(9-MeA- N1)](NO 3) 2·H 2O

Previously studied ( 1H NMR) mono- and dinuclear complexes obtained by reactions of [(dien)Pt(II)] with 9-methyladenine (9-MeA) have been isolated and characterized: [(dien)Pt(9-MeA- N 7)](NO 3) 2·H 2O ( 1), [(dien)Pt(9-MeA- N 1)](NO 3) 2·H 2O ( 2) and {[(dien)Pt] 2(9-MeA- N 7, N 1)}(NO 3) 4·2H 2O(3). Complex 2, which is only the third structurally characterized adenine complex having a metal exclusively bound through N(1), crystallizes in the space group P 1 with unit cell dimensions a=8.797(2), b=10.701(3), c=12.156(3) Å, α=101.93(3), β=118.18(3), γ=101.11(3)°, V=929.4 Å 3, Z=2. Trinuclear derivatives of 2, {(NH 3) 2Pt[( N 7-9-MeA- N 1)Pt(dien)] 2}(NO 2) 6·6H 2O, ( 4), ( 5) were prepared by reaction of 2 with cis- and trans-(NH 3) 2Pt(II), respectively. Oxidation of 1 and 2 with H 2O 2 gave Pt(IV) compounds of composition trans-[Pt(OH) 2(dien)(9-MeA- N 7)](ClO 4) 2·2H 2O ( 6) and trans-[Pt(OH) 2(dien)(9-MeA- N 1)]X 2· nH 2O (X=ClO 4 −, n=2 ( 7a); X=NO 3 −, n=0, ( 7b)). The mixed Pt(IV),Pt(II) complex trans- [(OH) 2Pt(dien)( N 1-9-MeA- N 7)Pt(dien)](ClO 4) 4·2H 2O ( 8) was obtained from 7 and (dien)Pt(II). The compounds prepared were characterized by elemental analysis and a variety of spectroscopic methods such at 1H NMR, UV and Raman. Acid-base equilibria were determined for several of the compounds and the formations of heteronuclear complexes between Ag + and 1 and 2, respectively, were followed by 1H NMR.

Synthesis and reactivity of trinuclear complexes of platinum containing the single bridging ligand SC4H8. Molecular structure of [NBu4]2[trans-PtCl2{(µ-SC4H8)Pt(C6F5)3}2

Trinuclear complexes of the type [NBu4]2[trans-PtX2{(µ-SC4H8)Pt(C6F5)3}2](X = Cl,Br,I, or C6F5;SC4H8= tetrahydrothiphene)(1)–(4) have been prepared form trans-[PtX2(SC4H8)2] and NBu4[Pt(C6H5)3(OCMe2)](molar ratio 1:2). The SC4H8 ligands act as the single bridge between the central platinum atom and the two terminal ones. Attemps to prepare similar trinuclear complexes with singly bridging halide ligands failed since the reaction between trans-[PtCl2(py)2](py = pyridine) and NBu4[Pt(C6F5)3(OCMe2)](molar ratio 1:2) does not take place, while trans-[Ptl2(py)2] or [PtBr2(cod)](cod = cyclo-octa-1,5-diene), under similar conditions, yield cis-[Pt(C6F5)2(py)2] and [NBu4]2[Pt2(µ-I)2(C6F5)4] or [Pt(C6F5)2(cod)] and [NBu4]2[Pt2(µ-Br)2(C6F5)4] respectively. The trinuclear derivatives (1) and (3) react with neutral ligands L to give different mononuclear complexes, depending on the ligand L: when L = PPh3, NBu4[Pt(C6F5)3(SC4H8)] and cis-[PtX2(PPh3)2]; when L = CO, NBu4[Pt(C6F5)3(CO)] and trans-[PtCl2(SC4H8)2]. The molecular structure of [NBu4]2[trans-PtCl2{(µ-SC4H8)Pt(C6F5)3}2] has been established by a single-crystal X-ray diffraction study. The compound forms triclinic cryctals in the space group P, with Z= 1 and unit-cell dimensions a= 12.463(3), b= 12.487(3), c= 15.137(3)A, α= 85.68(15), β= 66.04(2), and γ= 87.04(1)°. The structure was refined to R= 0.048 and R′= 0.048. The central platinum atom in the trinuclear anion [trans-PtCl2{(µ-SC4H8)Pt(C6F5)3}2]2– lies on a crystallographic centre of symmetry and is bonded to two Cl atoms and two S atoms (from two SC4H8 ligands), the latter acting as bridging ligands between the central and the terminal Pt atoms.

Copper (II) complexes of a macrocyclic binucleating ligand which exhibit two-electron oxidation and two-electron reduction. Structure of [Cu2(C24H34N4O2)(CH3OH)2](ClO4)2, a macrocyclic dicopper(II) complex involving coordinated methanol

The saturated ligand H2L1, derived by template condensation of 4-methyl-2,6-diformylphenol and 1,3-diaminopropane, followed by borohydride reduction, generates binuclear, antiferromagnetically coupled, copper(II) complexes which exhibit cyclic voltammetry involving two one-electron oxidation steps (E1/2 = 1.1 to 1.2 V, 1.3 to 1.4 V; Pt/CH3CN/SCE) and two one-electron reduction steps (E1/2 = −0.75 to −0.76 V, −0.89 to −0.90 V (GC/DMSO/SCE) with the formation of Cu(III)–Cu(III) and Cu(I)–Cu(I) and mixed oxidation state species. A trinuclear derivative, [Cu2(L1)(CuCl4)], appears to contain a spin-coupled binuclear species bound to a magnetically isolated tetrachlorocuprate(II) entity. The complex [Cu2(L1)(CH3OH)2](ClO4)2 forms brown crystals with a = 8.6516(7), b = 11.6832(9), c = 16.7205(6) Å, β = 92.596(5)°, P21/n, Z = 2, Rf = 0.037 and has a copper–copper separation of 3.088(1) Å and two weakly bound trans-axial methanol molecules (Cu—O, 2.413(4) Å). Variable temperature magnetic studies on [Cu2(L1)(ClO4)2] and [Cu2(L1)](ClO4)2 indicate strong antiferromagnetic exchange (−2J = 824 ± 5cm−1, 827 ± 7cm−1, respectively) in both cases.