Electronic communication through a poly-yne carbonyldicobalt complex containing an open linear triosmium cluster

Arnanz, Avelina; Marcos, M.L.; Delgado, Salomé; González‐Velasco, J.; Moreno, C.

doi:10.1039/b812195h

Cited by 4 publications

(5 citation statements)

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“…The 13 C{ 1 H} NMR chemical shifts of the carbonyl ligands bonded to the Co 2 units, in all complexes, appear as one or two signals at around δ 199 ppm or δ 202 and 207 ppm, which indicates a fast interchange on the NMR scale. The resonances of the free and coordinated acetylene units were easily observed, and the chemical shifts of their carbon atoms are in the range of analogous complexes (δ 80–105 ppm). ,,,, Azobenzene carbon resonances appear between δ 120 and 155 ppm. The chemical shift for the C 4 atom in 4 , 6 , 8 , and 10 is found to be very sensitive to cobalt complexation on the adjacent alkyne and shows a significant downfield shift (from 126 to 142 or 149 ppm) when they become 5 , 7 , 9 , and 11 (Table ).…”

Section: Resultsmentioning

confidence: 97%

“…The 13 C{ 1 H} NMR spectrum of 15 shows the resonances due to the coordinated carbon atoms in addition to those of the carbon chains, and, in the same manner as 7 and 11 , the chemical equivalence of the molecule is demonstrated. The unambiguous assignments of all carbon atoms have been carried out by using homonuclear and heteronuclear two-dimensional correlation spectroscopy experiments and by comparison with analogous compounds. ,,,, The room-temperature 31 P{ 1 H} NMR spectra in CDCl 3 present a broad singlet that is shifted to higher frequencies (ca. 36 and 13 ppm for dppm and dmpm complexes, respectively) with respect to that of the free phosphine ligand because of the coordination.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Properties of New Dimeric η²-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

Moreno¹,

Arnanz²,

Medina³

et al. 2015

Organometallics

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The reaction between 4,4′-diiodoazobenzene (0) with excess trimethylsilylacetylene or dec-1-yne in the presence of catalytic amounts of PdCl 2 (PPh 3 ) 2 and CuI, Sonogashira coupling conditions, gave rise to the formation of 4,4′-bis(trimethylsilylethynyl)azobenzene (1) and 4,4′-bis(dec-1-ynyl)azobenzene (2), in good yield, in addition to icosa-9,11-diyne (3) as byproduct in the last case. The analogous reactions from 0 and the alkynyl-cobalt complexes Co 2 (CO) 4 (μ-L-L)(μ 2 -η 2 -SiMe 3 C 2 )](CCH) (L-L = dppm, dmpm) afforded 12−14.Complexes 4−7 and 15 have been obtained by direct reaction between Co 2 (CO) 8 and the organic ligands 1−3. In order to increase the stabilization of Co−Co bonds, diphenylphosphinomethane-substituted alkyne-carbonyl complexes 8−11 were prepared by substitution reaction of carbonyl ligands in the presence of Me 3 NO at the Co 2 (CO) 6 units from 4−7. All products were characterized by analytical and spectroscopic data (IR, 1 H, 13 C, and 31 P NMR, and MS). Crystals of 9 suitable for single-crystal X-ray diffraction were grown, and the molecular structure of this compound is discussed. In this paper we report a comparative electrochemical study of these complexes by means of cyclic and square-wave voltammetry techniques, the trans−cis photoisomerization study of azobenzene compounds, and the thermotropic liquid-crystalline behavior. ■ INTRODUCTIONAzobenzene and its derivatives constitute a family of dye molecules known since the middle of the last century. 1 These chromophores are very versatile molecules that have received much attention in both fundamental and applied research areas. 2 Basically, they are characterized by intense color, high thermal stability (up to 350°C), and a trans to cis reversible isomerization of the NN double bond upon UV light irradiation, whereas the reverse isomerization can take place by visible light irradiation or by heating, the trans-form being generally more stable than the cis-form. 3 Photoinduced isomerization involves dramatic structural rearrangements: the distance between the para carbon atoms in the molecule decreases from about 9.0 Å in the trans-form to 5.5 Å in the cisform. Furthermore, the change in the configuration leads to a significant increase in the dipole moment. The trans-form has no dipole moment, while the dipole moment of the nonplanar cis compound is 3.0 D. 4 Azobenzene and nearly all its monosubstituted derivatives show a strong band in the UV region attributed to the π−π* transition at ca. 290 nm in the cis-form (depending on the solvent) and at ca. 320 nm in the trans-form and a much weaker band in the visible region (around 450 nm), due to the n−π* transition. 5 On conversion to the cis-isomer, the π−π* band shifts to shorter wavelengths, and the intensity of the n−π* absorption increases. Usually, four mechanisms for the trans−cis reaction are considered: rotation, inversion, concerted inversion, and inversion-assisted rotation. The actual mechanism depends on the exact surroundings of the azo group. 3,6 Since the tw...

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Synthesis and Properties of New Dimeric η²-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

Moreno¹,

Arnanz²,

Medina³

et al. 2015

Organometallics

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“…Fc(C C) n {Ru 2 (dmba) 4 }(C C) n Fc (Fc = ferrocenyl, dmba = N,N'-dimethylbenzamidinate, n = [39] or M 6 (dppm) 2 clusters [40] are known, while a few complexes contain poly-yndiyl-metal fragments to which are bridged by M 6 (dppm) 2 clusters [41] or complexed to Co 2 (CO) 4 (L) 2 [L 2 = (CO) 2 , dppm] [42] or Os 3 (CO) n (n = 10, 11) [43, 44] groups. Reactions of {Cp(Ph 3 P) 2 Ru} 2 { -(C C) n } (n = 1, 2) with Fe 2 (CO) 9 afford {Cp(Ph 3 P) 2 Ru}C m {Fe 3 (CO) 9 }C m {Ru(PPh 3 ) 2 Cp} (m = 3, 5, resp.).…”

Section: Introductionmentioning

confidence: 99%

Syntheses and structures of some complexes containing M3(μ-dppm)3 moieties (M = Cu, Ag) linking C4{M′Lx} groups [M′Lx= Re(CO)3(Bu2-bpy), Ru(dppe)Cp∗]

Bruce

Ellis

Halet

et al. 2016

Inorganica Chimica Acta

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et al.. Syntheses and structures of some complexes containing M3(µ-dppm)3 moieties (M = Cu, Ag) linking C4M'Lx groups [M'Lx = Re(CO)3(But 2-bpy), Ru(dppe)Cp⋆]. Inorganica Chimica Acta, Elsevier, 2016, 453, pp.ABSTRACT Reactions between [Ru(C CC CH)(dppe)Cp*] and [M 2 (NCMe) x (dppm) 2 ] 2+ (M = Cu, x = 4; Ag, x = 2) have given complexes containing M 3 ( -dppm) 3 clusters attached to one or two -C CC C[Ru(dppe)Cp*] groups. Single crystal X-ray studies are recorded for [{M 3 (μdppm) 3 }{μ 3 -C≡CC≡C[Ru(dppe)Cp*]}](BF 4 ) 2 ·nS (M = Cu, Ag) [isomorphous (orthorhombic) for S = (ill-defined) acetone]. A different (triclinic) polymorph has also been defined for M = Ag, nS = 5THF. Together with [{Cu 3 ( -dppm) 3 }{ 3 -C CC C[Ru(dppe)Cp*]} 2 ]PF 6 ·4Me 2 CO, the structures definitively confirm the complexes as clear examples of mono-or bis-diyndiyl-M 3 systems, devoid of close approaches to the vacant M 3 faces of the former by counterions in the case of their acetone solvates, except in the case of the BF 4 counterion in the AgBF 4 / thf solvate. Cyclic voltammetric studies suggest that there are only weak electronic interactions between the ruthenium centres in the bis(diynyl) complexes, consequent upon weak overlaps between the carbon chain and the M 3 ( -dppm) 3 clusters, as confirmed by DFT calculations on model complexes [{M 3 ( -dHpm) 3 }{C CC C[Ru(dHpe)Cp]} n ] 3-n [n = 1, 2; dHpm = CH 2 (PH 2 ) 2 , dHpe = H 2 P(CH 2 ) 2 PH 2 ]. The complexes [Ag 3 Cl 2 (dppm) 3 ]PF 6 , [M 3 ( -dppm) 3 (X){μ 3 -C CC C[Re(CO) 3 (Bu t 2 -bpy)]}]PF 6 (M = Cu, X = C CC C[Re(CO) 3 (Bu t 2 -bpy)]; M = Ag; X = Cl), [Ag 6 ( -dppm) 4 {C CC C[Re(CO) 3 (Bu t 2 -bpy)]} 4 ](PF 6 ) 2 have also been prepared and structurally characterised. In the M 3 clusters, some asymmetry in the attachment of at least one of the 3 ligands is apparent, which results from interactions with solvate molecules. ___________

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“…For the osmium systems, the observed chemistry includes intramolecular rearrangement or cyclization of the ligand under mild conditions and displays a wide range of coordination modes. , It is known that the activated cluster [Os 3 (CO) 10 (CH 3 CN) 2 ] typically reacts with diynes (RCCCCR, R = Me, Et, Ph, Bu t , SiMe 3 , 2-thiophenyl, ferrocenyl), at room temperature, to form the 48-electron clusters [Os 3 (μ 3 ,η 2 -RC 2 C 2 R)(μ-CO)(CO) 9 ], in which only one of the alkyne units is coordinated. , When R = Me, metallacyclic products incorporating two diynes are also obtained . Moreover, reactions with diynes (RCCCCR, R = 2-thiophenyl, ferrocenyl, Co 2 (CO) 4 (dppm)(μ 2 ,η 2 -C 2 SiMe 3 )C 4 H 2 S) involving [Os 3 (CO) 11 (CH 3 CN)] can lead to the formation of the linear 50-electron clusters [Os 3 (μ 3 ,η 1 :η 2 :η 1 -RC 2 C 2 R)(CO) 11 ], in which both alkyne units are coordinated in a parallel mode. ,, On the other hand, reactions of [Os 3 (CO) 10 (CH 3 CN) 2 ] with terminal monoalkynes, RCCH, give the triply bridging alkyne 48-electron clusters [Os 3 (μ 3 ,η 2 -alkyne)(CO) 10 ], which often lead to hydrogen transfer to the metal to give the hydrido acetylide 46-electron complexes [Os 3 H(μ 3 ,η 2 -alkyne)(CO) 9 ], where the unsaturation resulting from the loss of CO is compensated by oxidative addition, and the edge-bridged 47-electron clusters [Os 3 (μ-H){μ,η 1 :μ,η 2 -alkyne)(CO) 10 ] …”

Section: Introductionmentioning

confidence: 99%

New Method for Intramolecular Cyclization of Osmium-Coordinated Diynes Avoiding Os₃(μ-H)₂(CO)₁₀ as Starting Material

Arnanz¹,

Moreno²,

Marcos³

et al. 2011

Organometallics

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A new method of synthesis was carried out for the preparation of the hydride clusters [Os3(μ-H)(CO)9{μ3,η1:η3:η1-RC2COHCCR}] (R = C4H3S (1a), BrC4H2S (1b), Ph (1c)) by reaction between RCCCCR (R = C4H3S (a), BrC4H2S (b), Ph (c)) and the “non-hydride” [Os3(CO)11(CH3CN)] in dichloromethane at room temperature and in the presence of water, avoiding the starting material [Os3(μ-H)2(CO)10]. The complexes [Os3(μ-CO)(CO)9{μ3,η1:η2:η1-RC4R}] (R = C4H3S (2a), BrC4H2S (2b), Ph (2c)) were also obtained as byproducts. 1a−c and 2a−c contain a “closed” Os3 triangular core in μ3,η1:η3:η1-allylic and μ3,η1:η2:η1-alkyne coordination modes, respectively. When the reaction is carried out in wet polar and donor solvents [Os3(μ-H)(CO)9{μ3,η1:η3:η1-RC2CHCOCR}] (R = C4H3S (3a), BrC4H2S (3b), Ph (3c)) are obtained, where the organic ligand turns into a furan ring by an intramolecular cyclization process. These reactions proceed through 1a−c as intermediates, identified by 1H NMR. Therefore, 3a−c have also been obtained as the only products in high yield (ca. 98%), when 1a−c were stirred in dry donor solvents at room temperature. In order to get further information about the possible mechanisms that take place, the reactions have been studied using D2O and different solvents. 1a,c, 2b, and 3c have been characterized by single-crystal X-ray diffraction analyses. A possible pathway for this reaction is suggested.

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Electronic communication through a poly-yne carbonyldicobalt complex containing an open linear triosmium cluster

Cited by 4 publications

References 61 publications

Synthesis and Properties of New Dimeric η²-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

Synthesis and Properties of New Dimeric η²-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

Syntheses and structures of some complexes containing M3(μ-dppm)3 moieties (M = Cu, Ag) linking C4{M′Lx} groups [M′Lx= Re(CO)3(Bu2-bpy), Ru(dppe)Cp∗]

New Method for Intramolecular Cyclization of Osmium-Coordinated Diynes Avoiding Os₃(μ-H)₂(CO)₁₀ as Starting Material

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Electronic communication through a poly-yne carbonyldicobalt complex containing an open linear triosmium cluster

Cited by 4 publications

References 61 publications

Synthesis and Properties of New Dimeric η2-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

Synthesis and Properties of New Dimeric η2-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

Syntheses and structures of some complexes containing M3(μ-dppm)3 moieties (M = Cu, Ag) linking C4{M′Lx} groups [M′Lx= Re(CO)3(Bu2-bpy), Ru(dppe)Cp∗]

New Method for Intramolecular Cyclization of Osmium-Coordinated Diynes Avoiding Os3(μ-H)2(CO)10 as Starting Material

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Synthesis and Properties of New Dimeric η²-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

Synthesis and Properties of New Dimeric η²-Diyne Complexes of Cobalt Linked through an Azobenzene Ligand

New Method for Intramolecular Cyclization of Osmium-Coordinated Diynes Avoiding Os₃(μ-H)₂(CO)₁₀ as Starting Material