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Trinuclear Complexes (trinuclear + complex)

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Chemistry	100%

Selected Abstracts

Nucleophilic Addition of Water and Alcohols to Dicyanonitrosomethanide: Ligands with Diverse Bonding Modes in Magnetically Coupled d-Block Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2010
Anthony S. R. Chesman
Abstract Ligands resulting from the transition-metal-promoted nucleophilic addition of water or an alcohol to dicyanonitrosomethanide ions (dcnm) have been utilised in the formation of a large series of polynuclear complexes. Addition of water to dcnm results in formation of carbamoylcyanonitrosomethanide (ccnm); deprotonation of this ligand gives amidocarbonyl(cyano)nitrosomethanide (acnm), which has been incorporated into the trinuclear complex [Cu3(acnm)2(dmae)2(H2O)2] [dmae = 2-(dimethylamino)ethoxide] (1) which shows strong antiferromagnetic coupling with an exchange coupling constant, J = ,500 cm,1. [Cu(acnm)(NH3)2], (2) marks the first instance of acnm facilitating the formation of a coordination polymer, namely a 1D chain with intramolecular hydrogen bonding. Attempts to synthesise 2 through different reaction conditions instead resulted in the mononuclear [Cu(acnm)(NH3)2(py)] (py = pyridine) (3). The addition of ethanol to dcnm results in cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) which features in the mononuclear [Cu(cenm)2(H2O)2] (4) and polymeric {[Cu(cenm)2]2·H2O}, (5). The latter is the first example of the cenm ligand in a coordination polymer and has a highly unusual coordination mode through the nitrile groups and extremely weak antiferromagnetic coupling. {[Mn3(ccnm)2(EtOH)2(OAc)4]·2EtOH}, (6) and (Et4N)2[Cu(ccnm)4] (7) contain previously unobserved coordination modes of the ccnm ligand while the complex [Mn(cmnm)3Mn(bipy)(MeOH)](ClO4) (8) {cmnm = cyano[imino(methoxy)methyl]nitrosomethanide, bipy = 2,2,-bipyridine} displays weak antiferromagnetic coupling between manganese atoms with J = ,1.44 cm,1. A change in the solvent systems used in the synthesis of 7 results in the formation of the mononuclear complexes [Mn(bipy)2(dcnm)2] (9) or [Mn(bipy)2(H2O)(dcnm)](dcnm)·H2O (10) and [Mn(bipy)2(dcnm)(H2O)](dcnm) (11). The addition of ethlyene glycol monomethyl ether to dcnm gives cyano[imino(2-methoxyethoxy)methyl]nitrosomethanide (cgnm) and the formation of [Cu(cgnm)2(H2O)2] (12). [source]

Reactivity of Cationic Lanthanide(III) Monoporphyrinates towards Anionic Cyanometallates , Preparation, Crystal Structure, and Luminescence Properties of Cyanido-Bridged Di- and Trinuclear d,f Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2008
Xunjin Zhu
Abstract The metathesis reaction between two equivalents of [Ln(tpp)(H2O)3]Cl (Ln = Yb, Er; tpp2, = tetraphenylporphyrinate dianion) and one equivalent of cyanometallate in dmf at room temperature under nitrogen for 24 hours gave the cyanido-bridged d,f trinuclear complexes [{Ln(tpp)(dmf)n}2{(,-NC)2M(CN)2}] (Ln = Yb, n = 2, M = Ni, 1; Ln = Er, n = 3, M = Ni, 2; Ln = Yb, n = 2, M = Pt, 3; Ln = Er, n = 3, M = Pt, 4), a trinuclear complex [{Er(tpp)(dmf)2}{(,-NC)2Fe(CN)4}{Er(Htpp)(dmf)2}] (5), and a dinuclear complex [{Er(tpp)(dmf)(H2O)}(,-NC)Ag(CN)] (6) when the cyanometallate used was the dianion [M(CN)4]2, (M = Ni, Pt), the trianion [Fe(CN)6]3,, and monoanion [Ag(CN)2],, respectively. The solid-state structures of these complexes were ascertained by X-ray crystallography. Photoluminescence studies of complexes 1,4 showed that these complexes displayed photophysical properties characteristic of normal metal,porphyrinato complexes. Their absorption bands and emission peaks in the visible region are typical of the intraligand ,,,* transitions of the porphyrinato ligand. Furthermore, these complexes also exhibited emission characteristic of the lanthanide(III) ion in the near-infrared (NIR) region, which was quenched by the cyanometallates. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Unconventional Spin Crossover in Dinuclear and Trinuclear Iron(III) Complexes with Cyanido and Metallacyanido Bridges

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2009
alitro
Abstract A nonsymmetrical triamine, 1,6-diamino-4-azahexane, was Schiff-condensed with (X-substituted) o -salicylaldehyde to yield pentadentate ligands X-L5: salpet and MeBu-salpet. These ligands form mononuclear, dinuclear, and trinuclear FeIII complexes, whose structures were determined by single-crystal X-ray analysis. Of the mononuclear complexes, [FeIII(salpet)Cl] and [FeIII(MeBu-salpet)Cl] are high spin (S = 5/2), whereas [FeIII(salpet)CN]·MeOH is low spin (S = 1/2). The dinuclear and trinuclear complexes show a kind ofthermally induced spin crossover. The dinuclear complex [L5FeIII(CN)FeIIIL5](ClO4)·2H2O (L5 = salpet) is a mixed-spin assembly: the C -coordinated FeIII center is low spin (L) and the N -coordinated FeIII center is high spin (H) at low temperature; an antiferromagnetic interaction occurs between them. This LH reference state is mixed with the LL one. Upon heating, the system shows an increasing content of the HH state. Also, the dinuclear complex [L5FeIII(CN)FeIIIL5](BPh4)·2MeCN (L5 = MeBu-salpet) exhibits a spin transition between LH and HH spin pairs. The mixed-valence trinuclear complex [L5FeIII{FeII(CN)5(NO)}FeIIIL5]·0.5MeOH·3.75H2O (L5 = salpet) shows spin crossover with a residual high-spin fraction at liquid He temperature owing to the LL + LH ground state. The metallacyanido-bridged complex [L5FeIII{Ni(CN)4}FeIIIL5]·2MeOH (L5 = MeBu-salpet) contains a high-spin pair, HH, over the whole temperature interval with a ferromagnetic exchange interaction. A theoretical model was outlined that allows simultaneous fitting of all available experimental data (magnetic susceptibility, magnetization, high-spin mole fraction obtained from the Mössbauer spectra) on a common set of parameters. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Reactivity of Cationic Lanthanide(III) Monoporphyrinates towards Anionic Cyanometallates , Preparation, Crystal Structure, and Luminescence Properties of Cyanido-Bridged Di- and Trinuclear d,f Complexes

Coordination Chemistry of 3-Mercapto-2-(mercaptomethyl)propanoic Acid (Dihydroasparagusic Acid) with Iron and Nickel

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2006
Phillip I. Volkers
Abstract The first transition-metal complexes bearing the natural product dihydroasparagusic acid, (HSCH2)2CHCO2H, as a ligand are reported. Various coordination modes and nuclearities are demonstrated for the chelating ligand by a series of iron and nickel complexes. Fe2[(SCH2)2CHCO2H](CO)6 retains carbonyl substitution reactivity typical of Fe2(SR)2(CO)6 complexes, yet carboxy coordination to FeI was unobserved. Coupling of the carboxylic acid with amines yields the corresponding amides Fe2[(SCH2)2CHC(O)NHR](CO)6 (R = Et, gly,O,tBu). Fe2[(SCH2)2CHCO2H](CO)4(PMe3)2 catalyzes H2 production, but no better than unfunctionalized alkyl dithiolate analogs. Reactions of the ligand with NiCl2(dppe) afforded mono-, di-, and trinuclear complexes. Noteworthy is Ni3[(SCH2)2CHCO2]2(dppe)2, which features an octahedrally coordinated NiII center linked to a pair of square-planar NiII centers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Do Trinuclear Triplesalen Complexes Exhibit Cooperative Effects?

CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2010
Characterization, Enantioselective Catalytic Sulfoxidation by Chiral Trinuclear FeIII Triplesalen Complexes, Synthesis
Abstract The chiral triplesalen ligand H6chand provides three chiral salen ligand compartments in a meta -phenylene arrangement by a phloroglucinol backbone. The two diastereomeric versions H6chandRR and H6chandrac have been used to synthesize the enantiomerically pure chiral complex [(FeCl)3(chandRR)] (3RR) and the racemic complex [(FeCl)3(chandrac)] (3rac). The molecular structure of the free ligand H6chandrac exhibits at the terminal donor sides the O-protonated phenol,imine tautomer and at the central donor sides the N-protonated keto,enamine tautomer. The trinuclear complexes are comprised of five-coordinate square-pyramidal FeIII ions with a chloride at the axial positions. The crystal structure of 3rac exhibits collinear chiral channels of ,11,Å in diameter making up 33.6,% of the volume of the crystals, whereas the crystal structure of 3RR exhibits voids of 560,Å3. Mössbauer spectroscopy demonstrates the presence of FeIII high-spin ions. UV/Vis spectroscopy is in accordance with a large delocalized system in the central backbone evidenced by strong low-energy shifts of the imine ,,,* transitions relative to that of the terminal units. Magnetic measurements reveal weak intramolecular exchange interactions but strong magnetic anisotropies of the FeIII ions. Complexes 3rac and 3RR are good catalysts for the sulfoxidation of sulfides providing very good yields and high selectivities with 3RR being enantioselective. A comparison of 3RR and [FeCl(salen,)] provides higher yields and selectivities but lower enantiomeric excess values (ee values) for 3RR relative to [FeCl(salen,)]. The low ee values of 3RR appeared to be connected to a strong ligand folding in 3RR, opening access to the catalytically active high-valent Fe,O species. The higher selectivity is assigned to a cooperative stabilization of the catalytically active high-valent Fe,O species through the phloroglucinol backbone in the trinuclear complexes. [source]

Unprecedented Stereoselective Synthesis of Catalytically Active Chiral Mo3CuS4 Clusters

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2006
Marta Feliz Dr.
Abstract Cluster excision of polymeric {Mo3S7Cl4}n phases with chiral phosphane (+)-1,2-bis[(2R,5R)-2,5-(dimethylphospholan-1-yl)]ethane ((R,R)-Me-BPE) or with its enantiomer ((S,S)-Me-BPE) yields the stereoselective formation of the trinuclear cluster complexes [Mo3S4{(R,R)-Me-BPE}3Cl3]+ ([(P)- 1]+) and [Mo3S4{(S,S)-Me-BPE}3Cl3]+ ([(M)- 1]+), respectively. These complexes posses an incomplete cuboidal structure with the metal atoms defining an equilateral triangle and one capping and three bridging sulfur atoms. The P and M symbols refer to the rotation of the chlorine atoms around the C3 axis, with the capping sulphur atom pointing towards the viewer. Incorporation of copper into these trinuclear complexes affords heterodimetallic cubane-type compounds of formula [Mo3CuS4{(R,R)-Me-BPE}3Cl4]+ ([(P)- 2]+) or [Mo3CuS4{(S,S)-Me-BPE}3Cl4]+ ([(M)- 2]+), respectively, for which the chirality of the trinuclear precursor is preserved in the final product. Cationic complexes [(P)- 1]+, [(M)- 1]+, [(P)- 2]+, and [(M)- 2]+ combine the chirality of the metal cluster framework with that of the optically active diphosphane ligands. The known racemic [Mo3CuS4(dmpe)3Cl4]+ cluster (dmpe=1,2-bis(dimethylphosphanyl)ethane) as well as the new enantiomerically pure Mo3CuS4 [(P)- 2]+ and [(M)- 2]+ complexes are efficient catalysts for the intramolecular cyclopropanation of 1-diazo-5-hexen-2-one (3) and for the intermolecular cyclopropanation of alkenes, such as styrene and 2-phenylpropene, with ethyl diazoacetate. In all cases, the cyclopropanation products were obtained in high yields. The diastereoselectivity in the intermolecular cyclopropanation of the alkenes and the enantioselectivity in the inter- or intramolecular processes are only moderate. La reacción de escisión de la fase polimérica {Mo3S7Cl4}ncon la fosfina quiral (+)-1,2-bis[(2R,5R)-2,5-(dimetilfosfolan-1-il)]etano, (R,R)-Me-BPE, o con su enantiómero, (S,S)-Me-BPE, conduce a la formación estereoselectiva de los complejos clúster trinucleares [Mo3S4(R,R -Me-BPE)3Cl3]+([(P)- 1]+) y [Mo3S4(S,S -Me-BPE)3Cl3]+([(M)- 1]+), respectivamente. Estos complejos poseen una estructura de cubo incompleto, dónde los átomos metálicos definen un triángulo equilátero, con un azufre unido a tres átomos de molibdeno y tres azufres puente. Los símbolos P y M hacen referencia a la rotación de los átomos de cloro alrededor del eje C3, con el azufre apuntado dirigido hacia el observador. La incorporación de cobre a estos complejos trinucleares conduce a compuestos heterodimetálicos con estructura tipo cubano de fórmula [Mo3CuS4(R,R -Me-BPE)3Cl4]+([(P)- 2]+) y [Mo3CuS4(S,S -Me-BPE)3Cl4]+([(M)- 2]+) donde la quiralidad del precursor trinuclear se mantiene en el producto final. Los complejos catiónicos [(P)- 1]+, [(M)- 1]+, [(P)- 2]+y [(M)- 2]+combinan la quiralidad del esqueleto clúster con la de los ligandos difosfina. El clúster racémico [Mo3CuS4(dmpe)3Cl4]+(dmpe=1,2-bis(dimetilfosfino)etano), así como los complejos Mo3CuS4 enantioméricamente puros [(P)- 2]+o [(M)- 2]+son catalizadores eficaces para la reacción de ciclopropanación intramolecular de 1-diazo-5-hexen-2-ona (3) y para la ciclopropanación intermolecular de alquenos, estireno y 2-fenilpropeno, con etil diazoacetato. En todos los casos los productos de ciclopropanación se obtienen con rendimientos elevados. La diastereoselectividad en la ciclopropanación intermolecular de alquenos y la enantioselectividad en los procesos tanto inter- como intramoleculares son únicamente moderadas. [source]

Dithiolate-Bridged Fe-Ni-Fe Trinuclear Complexes Consisting of Fe(CO)3,n(CN)n (n=0, 1) Components Relevant to the Active Site of [NiFe] Hydrogenase

CHEMISTRY - AN ASIAN JOURNAL, Issue 6 2009
Satyanarayan Pal Dr.
Abstract Step-by-step: A trinuclear Fe-Ni-Fe complex 1 was synthesized from the reaction of [Fe(CO)4I2] with Li2[Ni(norbornane- exo -2,3-dithiolate)2]. The CO ligands in 1 were transformed into CN, upon treatment with ,N(SiMe3)2, and the monocyanide complex 3 and the dicyanide complex 4 were obtained. Complexes 3 and 4 were found to react with protonic acids, whereas 1 is robust. A dithiolate-bridged Fe-Ni-Fe trinuclear carbonyl complex [(CO)3Fe(,-ndt)Ni(,-ndt)Fe(CO)3] (1, ndt=norbornane- exo -2,3-dithiolate) has been synthesized from the reaction of [Fe(CO)4I2] and Li2[Ni(ndt)2]. This reaction was found to occur with concomitant formation of a tetranuclear cluster [Ni3(,-ndt)4FeI] (2). Treatment of 1 with Na[N(SiMe3)2] transforms some of the CO ligands into CN,, and the monocyanide complex (PPh4)[(CO)2(CN)Fe(,-ndt)Ni(,-ndt)Fe(CO)3] (3) and the dicyanide complex (PPh4)2[(CO)2(CN)Fe(,-ndt)Ni(,-ndt)Fe(CO)2(CN)] (4) were isolated. X-ray structural analyses of the trinuclear complexes revealed a Fe-Ni-Fe array in which the metal centers are connected by the ndt sulfur bridges and direct FeNi bonds. Hydrogen bonding between the CN ligand in 3 and cocrystallized ethanol was found in the solid-state structure. The monocyanide complex 3 and dicyanide complex 4 reacted with acids such as HOTf or HCl generating insoluble materials, whereas complex 1 did not react. [source]