Iron(II) and iron(III) complexes containing ethynyl thiophene fragments

The synthesis of the new complexes Cp*(dppe)FeCC2,5-C₄H₂SR (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl; dppe = 1,2-bis(diphenylphosphino)ethane; 2a, R = CCH; 2b, R = CCSi(CH₃)₃; 2c, R = CCSi(CH(CH₃)₂)₃; 3a, R = CC2,5-C₄H₂SCCH; 3c, R = CC2,5-C₄H₂SCCSi(CH(CH₃)₂)₃) is described. The ¹³C NMR and FTIR spectroscopic data indicate that the π-back donation from the metal to the carbon rich ligand increases with the size of the organic π-electron systems. The new complexes were also analyzed by CV and the chemical oxidation of 2a and 3c was carried out using 1 equiv of [Cp₂Fe][PF₆]. The corresponding complexes 2a[PF₆] and 3c[PF₆] are thermally stable, but 2a[PF₆] was too reactive to be isolated as a pure compound. The spectroscopic data revealed that the coordination of large organic π-electron systems to the iron nucleus produces only a weak increase of the carbon character of the SOMO for these new organoiron(III) derivatives.     

Syntheses and molecular structures of some phosphine-gold(I) derivatives of 1,3-diynes

The syntheses of several diynylgold(I) phosphine complexes, including Au(CCCCH){P(tol)₃} (1), Au(CCCCSiMe₃)(PR₃) (R = Ph 2-Ph, tol 2-tol), Au(CCCCFc)(PPh₃) (3), {(tol)₃P}Au(CC)_nAu{P(tol)₃} [n = 2 (4), 3 (6), 4 (7)], {(Ph₃P)Au}CCCC{Au[P(tol)₃]} (5), [ppn][Au{CCCCAu[P(tol)₃]}₂] (8), [Au₂(μ-I)(μ-dppm)₂][Au(CCCCSiMe₃)₂] (9), Hg{CCCCAu(PR₃)}₂ (R = Ph 10-Ph, tol 10-tol) and {(triphos)Cu}CCCC{Au[P(tol)₃]} (11) are described. Of these, the X-ray molecular structures of 1, 2-tol, 3, 4 and 9 have been determined.     

Some complexes containing carbon chains end-capped by M(CO)2Tp′ [M = Mo, W; Tp′ = HB(pz)3, HB(dmpz)3] groups

Complexes M(CCCSiMe₃)(CO)₂Tp′ (Tp′ = Tp [HB(pz)₃], M = Mo 2, W 4; Tp′ = Tp^∗ [HB(dmpz)₃], M = Mo 3) are obtained from M(CCCSiMe₃)(O₂CCF₃)(CO)₂(tmeda) (1) and K[Tp′].Reactions of 2 or 4 with AuCl(PPh₃)/K₂CO₃ in MeOH afforded M{CCCAu(PPh₃)}(CO)₂Tp′ (M = Mo 5, W 6) containing C₃ chains linking the Group 6 metal and gold centres.In turn, the gold complexes react with Co₃(μ₃-CBr)(μ-dppm)(CO)₇ to give the C₄-bridged {Tp(OC)₂M}CCCC{Co₃(μ-dppm)(CO)₇} (M = Mo 7, W 8), while Mo(CBr)(CO)₂Tp^∗ and Co₃{μ₃-C(CC)₂Au(PPh₃)}(μ-dppm)(CO)₇ give {Tp^∗(OC)₂Mo}C(CC)₂C{Co₃(μ-dppm)(CO)₇} (9) via a phosphine-gold(I) halide elimination reaction. The C₃ complexes Tp′(OC)₂MCCCRu(dppe)Cp^∗ (Tp′ = Tp, M = Mo 10, W 11; Tp′ = Tp^∗, M = Mo 12) were obtained from 2-4 and RuCl(dppe)Cp^∗ via KF-induced metalla-desilylation reactions. Reactions between Mo(CBr)(CO)₂Tp^∗ and Ru{(CC)_nAu(PPh₃)}(dppe)Cp^∗ (n = 2, 3) afforded {Tp^∗(OC)₂Mo}C(CC)_n{Ru(dppe)Cp^∗} (n = 2 13, 3 14), containing C₅ and C₇ chains, respectively. Single-crystal X-ray structure determinations of 1, 2, 7, 8, 9 and 12 are reported.     

Synthesis of di-, tri- and tetranuclear platinum(II) and copper(I) acetylide complexes

Heterobimetallic {cis-[Pt](μ-σ,π-CCPh)₂}[Cu(NCMe)]BF₄ (3a: [Pt] = (bipy)Pt, bipy = 2,2′-bipyridine; 3b: [Pt] = (bipy′)Pt, bipy′ = 4,4′-dimethyl-2,2′-bipyridine) is accessible by the reaction of cis-[Pt](CCPh)₂ (1a: [Pt] = (bipy)Pt, 1b: [Pt] = (bipy′)Pt]) with [Cu(NCMe)₄]BF₄ (2). Substitution of NCMe by PPh₃ (4) can be realized by the reaction of 3a with 4, whereby [{cis-[Pt](μ-σ,π-CCPh)₂}Cu(PPh₃)]BF₄ (5) is formed. On prolonged stirring of 3 and 5, respectively, NCMe and PPh₃ are eliminated and tetrametallic {[{cis-[Pt](η²-CCPh)₂}Cu]₂}(BF₄)₂ (6) is produced. Addition of an excess of NCMe to 6 gives heterobimetallic 3a.When instead of NCMe or PPh₃ chelating molecules such as bipy (7) are reacted with 3a then the heterobimetallic π-tweezer molecule [{cis-[Pt](μ-σ,π-CCPh)₂}Cu(bipy)]BF₄ (8) is formed. Treatment of 8 with another equivalent of 7 produced [Cu(bipy₂)]BF₄ (9) along with [Pt](CCPh)₂. However, when 3b is reacted with 1b in a 1:1 molar ratio then 10 and 11 of general composition [{[Pt](CCPh)₂}₂Cu]BF₄ are formed. These species are isomers and only differ in the binding of the PhCC units to copper(I). A possible mechanism for the formation of 10 and 11 is presented.The solid state structures of 6, 10 and 11 are reported. In 11 the [{cis-[Pt](μ-σ,π-CCPh)₂}₂Cu]⁺ building block is set-up by two nearly orthogonal positioned bis(alkynyl) platinum units which are connected by a Cu(I) ion, whereby the four carbon-carbon triple bonds are unsymmetrical coordinated to Cu(I). In trimetallic 10 two cis-[Pt](CCPh)₂ units are bridged by a copper(I) center, however, only one of the two PhCC ligands of individual cis-[Pt](CCPh)₂ fragments is η²-coordinated to Cu(I) giving rise to the formation of a [(η²-CCPh)₂Cu]⁺ moiety with a linear alkyne-copper-alkyne arrangement (alkyne = midpoint of the CC triple bond). In 6 two almost parallel oriented [Pt](CCPh)₂ planes are linked by two copper(I) ions, whereby two individual PhCC units, one associated with each Pt building block, are symmetrically π-coordinated to Cu.     

Synthesis, structures and some reactions of Ru(CCCCFc)(PP)Cp (PP = dppm, dppe) and related compounds

The compounds Ru(CCCCFc)(PP)Cp [PP = dppe (1), dppm (2)], have been obtained from reactions between RuCl(PP)Cp and FcCCCCSiMe₃ in the presence of KF (1) or HCCCCFc and K[PF₆] (2), both with added dbu. The dppe complex reacts with Co₂(CO)₆(L₂) [L₂ = (CO)₂, dppm] to give 3, 4 in which the Co₂(CO)₄(L₂) group is attached to the outer CC triple bond. The PPh₃ analogue of 3 (5) has also been characterised. In contrast, tetracyanoethene reacts to give two isomeric complexes 6 and 7, in which the cyano-olefin has added to either CC triple bond. The reaction of RuCl(dppe)Cp with HCCCCFc, carried out in a thf/NEt₃ mixture in the presence of Na[BPh₄], gave [Ru{CCC(NEt₃)CHFc}(dppe)Cp]BPh₄ (8), probably formed by addition of the amine to an (unobserved) intermediate butatrienylidene [Ru(CCCCHFc)(dppe)Cp]⁺. The reaction of I₂ with 8 proceeds via an unusual migration of the alkynyl group to the Cp ring to give [RuI(dppe){η-C₅H₄CCC(NEt₃)CHFc}]I₃ (9). Single-crystal X-ray structural determinations of 1, 2 and 4-9 are reported.     

Reactivity of [CpRh(η-C6H3NH2-2,6-i-Pr2)](OTf)2 toward phosphines and alkynes

The cationic aniline complex [Cp^∗Rh(η⁶-2,6-(Me₂CH)₂C₆H₃NH₂)](OTf)₂ (1) was prepared from either [Cp^∗Rh(η²-NO₃)(η¹-OTf)] or [Cp^∗Rh(OH₂)₃](OTf)₂ and 2,6-diisopropylaniline. Complex 1 underwent substitution with phosphines or phosphites, indicating the labile character of the η⁶-aniline ligand. Complex 1 mediated cycloaddition reactions of several alkynes in refluxing ethanol: the [2 + 2] dimerization for PhCCPh and the [2 + 2 + 1] trimerization for PhCCH and CH₃C₆H₄CCH. The unexpected cyclobutadiene complex [Cp^∗Rh(η⁴-C₄(C(O)CH₃)₂H(SiMe₃))] was obtained from complex 1 and Me₃SiCCCCSiMe₃ and structurally characterized by X-ray diffraction.     

Syntheses, structural, electrochemical and optical studies of heterobinuclear ruthenium-osmium alkynyl complexes

The complexes trans-[Os(CCC₆H₄-4-CCR)Cl(dppe)₂] (R = SiPrⁱ₃1, H 2), trans,trans-[(dppe)₂ClOs(CCC₆H₄-4-CC)RuX(dppe)₂] (X = Cl 3, CCC₆H₄-4-CCSiPrⁱ₃4), trans-[Os(CCC₆H₄-4-CCC₆H₄-4-CCR)Cl(dppe)₂] (R = SiPrⁱ₃5, H 6), and trans,trans-[(dppe)₂ClOs(CCC₆H₄-4-CCC₆H₄-4-CC)RuCl(dppe)₂] (7) have been synthesized, and the identities of 1, 2, and 6 confirmed by single-crystal X-ray diffraction studies. Cyclic voltammetry shows that the mononuclear complexes 1, 2, 5, and 6 are oxidized at potentials within a narrow range (0.45-0.49 V), in processes centered on the osmium ethynyl neighbourhood and for simplicity assigned as Os^II/III, while the heterobinuclear complexes 3, 4, and 7 exhibit lower oxidation potentials for Os^II/III and a second oxidation process assigned in a similar fashion to Ru^II/III; the difference in potential between the Os- and Ru-localized processes decreases as the π-bridge is lengthened. UV-vis-NIR spectroelectrochemical studies on 1 and 5 reveal the appearance on oxidation of a low-energy band ascribed to chloro to metal-ethynyl charge transfer. Osmium-centered oxidation at the heterobinuclear complexes 4 and 7 results in appearance of a low-energy band, which blue-shifts and increases in intensity on further oxidation to 4²⁺ and 7²⁺.     

Reactions of cyano(alkynyl)ethenes with some alkynyl- and diynyl-ruthenium complexes

Reactions of Ru(CCPh)(PPh₃)₂Cp with (NC)₂CCR¹R² (R¹ = H, R² = CCSiPrⁱ₃8; R¹ = R² = CCPh 9) have given η³-butadienyl complexes Ru{η³-C[C(CN)₂]CPhCR¹R²}(PPh₃)Cp (11, 12), respectively, by formal [2 + 2]-cycloaddition of the alkynyl and alkene, followed by ring-opening of the resulting cyclobutenyl (not detected) and displacement of a PPh₃ ligand. Deprotection (tbaf) of 11 and subsequent reactions with RuCl(dppe)Cp and AuCl(PPh₃) afforded binuclear derivatives Ru{η³-C[C(CN)₂]CPhCHCC[ML_n]}(PPh₃)Cp [ML_n = Ru(dppe)Cp 19, Au(PPh₃) 20]. Reactions between 8 and Ru(CCCCR)(PP)Cp [PP = (PPh₃)₂, R = Ph, SiMe₃, SiPrⁱ₃; PP = dppe, R = Ph] gave η¹-dienynyl complexes Ru{CCC[C(CN)₂]CRCH[CC(SiPrⁱ₃)]}(PP)Cp (15-18), respectively, in reactions not involving phosphine ligand displacement. The phthalodinitrile C₆H(CCSiMe₃)(CN)₂(NH₂)(SiMe₃) 10 was obtained serendipitously from (Me₃SiCC)₂CO and CH₂(CN)₂, as shown by an XRD structure determination. The XRD structures of precursor 7 and adducts 11, 12 and 17 are also reported.     

The reactions of some σ-alkynylnickel complexes with 7,7,8,8-tetracyanoquinodimethane

The σ-alkynyl complexes Ni(η⁵-C₅H₅)(PPh₃)-CC-R (1), Ni(η⁵-C₅H₅)(PPh₃)-CC-X-CCH (2) and Ni(η⁵-C₅H₅)(PPh₃)-CC-X-CC-Ni(η⁵-C₅H₅)(PPh₃) (3), reactwith 7,7,8,8-tetracyanoquinodimethane, TCNQ, at 30 °C by insertion of the alkyne CC into a CC(CN)₂ bond to give Ni(η⁵-C₅H₅)(PPh₃)-C{C₆H₄C(CN)₂}-C{C(CN)₂}-R (4), from 1, Ni(η⁵-C₅H₅)(PPh₃)-C{C₆H₄C(CN)₂}-C{C(CN)₂}-X-CCH (5), from 2, and Ni(η⁵-C₅H₅)(PPh₃)-C{C₆H₄C(CN)₂}-C{C(CN)₂}-X-CC-Ni(η⁵-C₅H₅)(PPh₃) (6),and Ni(η⁵-C₅H₅)(PPh₃)-C{C₆H₄C(CN)₂}- C{C(CN)₂}-X-C{C(CN)₂}-C{C₆H₄C(CN)₂}-Ni(η⁵-C₅H₅)(PPh₃) (7),from 3 {R = (a) C₆H₅, (b) 4-PhC₆H₄, (c) 4-Me₂NC₆H₄, (d) 1-C₁₀H₇ (1-naphthyl), (e) 2-C₁₀H₇ (2-naphthyl), (f) 9-C₁₄H₉ (9-phenanthryl), (g) 9-C₁₄H₉ (9-anthryl), (h) 3-C₁₆H₉ (3-pyrenyl), (i) 1-C₂₀H₁₁ (1-perylenyl), (j) 2-C₄H₃S (2-thienyl), (k) C₁₀H₉Fe (ferrocenyl = Fc) and (l) H; X = (a) nothing, (b) 1,4-C₆H₄, (c) 1,3-C₆H₄ and (d) 4,4′-C₆H₄-C₆H₄}. The reaction is regiospecificand the other possible insertion product, R-C{C₆H₄C(CN)₂}-C{C(CN)₂}-Ni(η⁵-C₅H₅)(PPh₃) etc., is not formed. Under the same conditions, there is no evidencefor the reaction of TCNQ with the -CCH of 2, PhCCH, 1,4-C₆H₄(CCH)₂ or FcCCH, or for the reaction of more than one CC(CN)₂ of TCNQ with a Ni-alkynyl moiety. Complexes 4-7 are all air-stable, purple solids which have been characterised by elemental analysis and spectroscopy (IR, UV-Vis, ¹H NMR and ¹³C NMR),and by X-ray diffraction for 4a, 4b and 4l. The UV-Vis spectra of 4-7 are very similar. This implies that all contain the same active chromophore which, it is suggested, is Ni-C(5)C₆H₄C(CN)₂ and not R-C(4)C(CN)₂. This isconsistent with the molecular structures of 4a, 4b and 4l which show that the first of these potentially chromophoric fragments is planar or close to it with an in-built potential for delocalisation, whilst in the second the aryl group R is almost orthogonal to the CC(CN)₂ plane. The molecular structures of 4a, 4b and 4l also reveal a short Ni?C(4) separation, indicative of a Ni → C(4) donor-acceptor interaction. The electrochemistry of 4a shows aquasi reversible oxidation at ca. 1 V and complicated reduction processes. It is typical of most 4, but 4l is different in that it shows the same quasi reversible oxidation at ca. 1 V but two reversible reductions at −0.26 and −0.47 V (vs. [Fe(η⁵-C₅Me₅)₂]^+/0 0.0 V).     

2,2′-Bipyrimidine transition metal complexes: Synthesis, reaction chemistry and solid state structures

2,2′-Bipyrimidine metal complexes with Ti, Mo, Fe, Ru, Pt, Ag, and Cu transition metal atoms have been synthesized and structurally characterized. These molecules were prepared by following synthesis methodologies. The reaction of 2,2′-bipyrimidine (1; bipym) with {[Ti](μ-σ,π-CCSiMe₃)₂}AgOTf ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti, OTf = OSO₂CF₃) (2) in a 1:1 molar ratio gave [{[Ti](μ-σ,π-CCSiMe₃)₂}Ag(bipym)]OTf (3) which on further treatment with another equivalent of 2 produced [({[Ti](μ-σ,π-CCSiMe₃)₂}Ag)₂(μ-1,2,3,4-bipym)](OTf)₂ (4). As consequence thereof, the coordination number of Ag(I) was changed from 3 to 4. A platinum-bipym complex with two acetylide substituents was accessible by the gradual reaction of 1 with K₂[PtCl₄] (5) and two equivalents of HCCR (7a, R = SiMe₃; 7b, R = Fc; 7c, R = Rc; Fc = (η⁵-C₅H₄)(η⁵-C₅H₅)Fe; Rc = (η⁵-C₅H₄)(η⁵-C₅H₅)Ru) in di-iso-propylamine and in presence of [CuI]. Originating from cis-[(bipym)Pt(CCR)₂] (8a, R = SiMe₃; 8b, R = Fc; 8c, R = Rc) diverse multinuclear complexes with two, three or four different transition metals could be obtained. These are: [((CO)₄Mo)(μ-1,2,3,4-bipym)Pt(CCFc)₂] (10), [(AgClO₄)(μ-1,2,3,4-bipym){[Pt(μ-σ,π-CCFc)₂]AgOClO₃}] (12), [(McCC)₂Pt(μ-1,2,3,4-bipym)({[Ti](μ-σ,π-CCSiMe₃)₂}M)]X (15a, Mc = Fc, M = Cu, X = PF₆; 15b, Mc = Rc, M = Cu, X = PF₆; 15c, Mc = Fc, M = Ag, X = ClO₄), and [(McCC)₂Pt(μ-1,2,3,4-bipym)PtCl₂] (17). Like other organometallic Pt-Ag tweezer complexes, compound 12 decomposed to give FcCC-CCFc (13). During prolonged stirring of 15a and 15b, respectively, [(McCC)₂Pt(μ-1,2,3,4-bipym)({[Ti](μ-σ,π-CCSiMe₃)(μ-σ,π-CCH)}M)]X (15′a, M = Cu, X = PF₆; 15′b, M = Cu, X = PF₆) was formed.The structures of 8b, 8c, 15a′, and 15b′ in the solid state are reported. All complexes exhibit the anticipated planar dinuclear Pt-M structure (M = Pt, Cu, Ag) with the 2,2′-bipyrimidine unit in a μ-1,2,3,4-bridging mode.Electrochemical investigations were carried out with 8a, 8b, and 8c and show that no significant influence of R on the bipym redox potentials exists. The typical redox behavior for the bipym, ferrocene, ruthenocene units and platinum were observed.     

Further chemistry of ruthenium butatrienylidene complexes

Several complexes have been obtained from reactions carried out in early attempts to prepare the diynyl complexes Ru(CCCCR)(dppe)Cp* (R = H, SiMe₃). These have been identified crystallographically as the acyl complex Ru{CCC(O)Me}(dppe)Cp* (3), the cationic imido complex [Ru{CCC(NH₂)Me}(dppe)Cp*]PF₆ (4), the binuclear butenynylallenylidene [{Ru(dppe)Cp*}₂{μ-CCC(OMe)CHCMeCC}]PF₆ (5), and the bis(ethynyl)cyclobutenylidene [{Ru(dppe)Cp*}₂{μ-CCC₄H₂(SiMe₃)CC}]PF₆ (6). NMR studies of 5 have revealed the existence of two isomers. Plausible routes for their formation from the putative butatrienylidene intermediate [Ru(CCCCH₂)(dppe)Cp*]⁺ (A) are discussed.     

Titanocene-based group-11 metal ions; solid-state structure of {[(η-C5H4SiMe3)2Ti(CCPh)2]2Ag}NO3

The reaction of [Ti](CCR)₂ {[Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; 1a, R = Fc, Fc = (η⁵-C₅H₄)Fe(η⁵-C₅H₅); 1b, R = Ph} with MX {2a, MX = [Cu(NCCH₃)₄]BF₄; M = Ag; 2b, X = ClO₄; 2c, X = NO₃} in a 2:1 molar ratio produces the trinuclear heterobimetallic (Ti₂M) or heptanuclear heterotrimetallic (Ti₂MFe₄) complexes [{[Ti](μ-σ,π-CCR)₂}₂M]X (R = Fc: 3a, M = Cu, X = BF₄; 3b, M = Ag, X = ClO₄. R = Ph: 3c, M = Cu, X = BF₄; 3d, M = Ag, X = ClO₄: 3e, M = Ag, X = NO₃) in high yield. Complexes 3c-3e are also accessible, when {[Ti](μ-σ,π-CCPh)₂}MX (M = Cu: 4a, X = FBF₃; M = Ag: 4b, X = OClO₃; 4c, X = ONO₂) is reacted with one equivalent of 1b. Transferring this reaction scheme to [Ti](CCSiMe₃)₂ (1c) only the formation of the heterobimetallic tweezer complex {[Ti](μ-σ,π-CCSiMe₃)₂}MX {4d, MX = [Cu(NCCH₃)]BF₄; 4e, MX = AgOClO₃} is observed which is attributed to the bulkiness of the acetylide-bound Me₃Si group. The solid-state structure of 3e is reported. In 3e, two [Ti](CCPh)₂ tweezer moieties are chelate-bound by their carbon-carbon triple bonds to a silver(I) ion, resulting in a pseudo-tetrahedral environment at the group-11 metal. is acting as counter-ion to cationic [{[Ti](CCPh)₂}₂Ag]⁺.Additionally, the result of cyclic voltammetric studies on [{[Ti](μ-σ,π-CCPh)₂}₂Cu]BF₄ (3c) is reported.     

A comparison between the reaction of P2Ph4 with [{Co2(CO)6}2(μ-η:μ-η-HOCH2CCCCCH2OH)] and the reaction of [Co2(μ-PPh2)2(CO)6] with HOCH2CCCCCH2OH

Reaction of P₂Ph₄ with the diyne-diol complex [{Co₂(CO)₆}₂(μ-η²:μ-η²-HOCH₂CCCCCH₂OH)] in toluene at 65 °C gives [{Co₂(μ-P₂Ph₄)(CO)₄}{Co₂(CO)₆}(μ-η²:μ-η²-HOCH₂CCCCCH₂OH)] (1). Thermolysis of 1 at 95 °C leads to [{Co₂(CO)₅}₂(μ-P₂Ph₄)(μ-η²:μ-η²-HOCH₂CCCCCH₂OH)](2) and (μ₂-PPh₂)(μ₂-CO)(CO)₇] (3). The structures of 1-3 have been established by X-ray crystallography. In 1, a pseudoequatorial P₂Ph₄ ligand bridges the cobalt-cobalt bond of a Co₂(CC)(CO)₄ unit. By contrast, in isomeric 2, a pseudoaxial P₂Ph₄ ligand spans two Co₂(CC)(CO)₅ units, a new coordination mode for [{Co₂(CO)₅L}₂(μ-η²:μ-η²-diyne)] complexes. Complex 3 arises from dehydration-cyclocarbonylation of the diyne-diol in 1 to give a 2(5H)-furanone, a process that has not been previously reported. Reaction of HOCH₂CCCCCH₂OH with [Co₂(μ-PPh₂)₂(CO)₆] at 80 °C in toluene gave [Co₃(μ-PPh₂)₃(CO)₆], [Co₂(CO)₆(μ-η²-HOCH₂CCCCCH₂OH)] and [Co₂{μ-η⁴-PPh₂C(CCCH₂OH)C(CH₂OH)CO}(μ-PPh₂)(CO)₄] (4). The regiochemistry of 4 was confirmed by X-ray crystallography.     

Preparation, structure and some chemistry of FcCCCCCCRu(dppe)Cp

The synthesis of Fc(CC)₃Ru(dppe)Cp (2) from Fc(CC)₃SiMe₃ and RuCl(dppe)Cp is described, together with its reactions with tcne to give the tetracyano-dienyl FcCCCC{C[C(CN)₂]}₂Ru(dppe)Cp (3) and -cyclobutenyl FcCCCC{CCC(CN)₂C(CN)₂}Ru(dppe)Cp (4), with Co₂(μ-dppm)_n(CO)_8−2n (n = 0, 1) to give FcC₂{Co₂(CO)₆}C₂{Co₂(CO)₆}CCRu(dppe)Cp (5) and FcCCCCC₂{Co₂(μ-dppm)(CO)₄}Ru(dppe)Cp (6), respectively, and with Os₃(CO)₁₀(NCMe)₂ to give Os₃{μ₃-C₂CCCC[Ru(dppe)Cp]}(CO)₁₀ (7). On standing in solution, the latter isomerises to the cyclo-metallated derivative Os₃(μ-H){μ₃-C[Ru(dppe)Cp]CCC[(η-C₅H₃)FeCp]}(CO)₈ (8). X-ray structural determinations of 1, 2, 6 and 7 are reported.     

Luminescent rhenium(I)-gold(I) hetero organometallics linked by ethynylphenanthrolines

The first luminescent rhenium(I)-gold(I) hetero organometallics, Re{phenAu(PPh₃)}(CO)₃Cl (3) and Re{(PPh₃)AuphenAu(PPh₃)}(CO)₃Cl (4), have been prepared using the gold(I) complex AuCl(PPh₃) (PPh₃ = triphenylphosphine) and the novel rhenium(I) complexes Re(phenH)(CO)₃Cl (5) (phenH = 3-ethynyl-1,10-phenanthroline) or Re(HphenH)(CO)₃Cl (6) (HphenH = 3,8-bis(ethynyl)-1,10-phenanthroline). All the present rhenium(I) complexes 3-6 were revealed to possess a facial configuration (fac-isomer) with respect to the three carbonyl ligands. The main frameworks for these new gold(I) organometallics were constructed by the Au-C σ-bonding (with the η¹-type coordination) between the ethynylphenanthrolines and the Au(I) phosphine unit. Re(I)-Au(I) heterometallics 3 and 4 have shown single phosphorescence from the ³MLCT excited state and this observation can be interpreted in terms of the efficient intramolecular energy transfer from the Au(I) unit to the Re(I) unit.     

Synthesis, structure, and magnetic properties of 2,2′-(buta-1,3-diyne-1,4-diyl)bis(4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide 1-oxyl)

An approach to the synthesis of nitronyl nitroxide 2,2′-(buta-1,3-diyne-1,4-diyl)bis(4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide 1-oxyl) (4) was developed. Compound 4 is the first diradical with nitronyl nitroxide groups directly linked through a diacetylene fragment. In solid phase the diradicals are arranged in stacks with parallel CC fragments, with the distances between the terminal carbon atoms of the neighboring diacetylene groups (T and d) being 6.170 and 4.466 Å, respectively, and the angle between the translation vector and the median line passing through the CCCC fragment of 45.9°. The values of T and d are outside the range of structural criteria allowing a topochemical reaction. Thus UV irradiation does not initiate solid phase polymerization of 4. After exposure at 373 K for 1 h the crystals of 4 turn dark-brown, become X-ray amorphous and lose the majority of their paramagnetic centers without significantly changing their mass. Upon further heating up to 400-420 K the product explodes, releasing about 360 kJ/mol of heat. A diluted solution of 4 in 1,4-dioxane produces an EPR spectrum typical of a strong exchange (a multiplet of nine broadened lines with A_4N = 0.35 mT), indicating the efficiency of the CCCC fragment as an exchange channel. The character of the experimental μ_eff(T) dependence for 4 indicates a strong intramolecular antiferromagnetic-type exchange interaction (J/k_B ∼ −104 K) and the dominating weak intermolecular ferromagnetic exchange.     

Ferrole-type compounds containing thiophenic or thiepinic rings in the 3,4-positions of the metallacycle

The new ferrole Fe₂(CO)₆[μ-η²,η⁴-(Fc)CC{C(H)C(R)S}CC(SiMe₃)] [R = SiMe₃ (1) and R = Fc (2)] and ruthenoles Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC{SC(Fc)C(H)}CC(Fc)] 3 and Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC(SCCFc)C(H)C(Fc)] 4, have been obtained from the reactions of M₃(CO)₁₂ (M = Fe, Ru) and FcCCSCCSiMe₃ through S-C bond activations and C-C coupling reactions. Thermolysis of Ru₂(CO)₆[μ₃-η²,η⁴,η³-(Me₃Si)CC{SC(Fc)C(SCCSiMe₃}Ru(CO)₃}CC(Fc)] alone and in the presence of HCCFc, yielded the compounds Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC{SC(Fc)C(SCCSiMe₃)}CC(Fc)] 5 and Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC{SC(Fc)C(SCCSiMe₃)C(H)C(Fc)}CC(Fc)] 6, respectively. The crystal structures of the compounds 1, 3, 4 and 6 are reported.