Activation of carbon suboxide (C3O2) by U(III) to form a cyclobutane-1,3-dione Ring.

The activation of C3O2 by the U(III) complex [U(η5-Cp’)3] (Cp’ = C5H4SiMe3) is described. The reaction results in the reductive coupling of three C3O2 units to form a tetranuclear complex with a central cyclobutane-1,3-dione ring, with concomitant loss of CO. Careful control of reaction conditions has allowed the trapping of an intermediate, dimeric bridging ketene complex, which undergoes insertion of C3O2 to form the final product

Bis(pentalene)dititanium chemistry: C–H, C–X and H–H bond activation

The reaction of the bis(pentalene)dititanium complex Ti2(μ:η5,η5-Pn†)2 (Pn† = C8H4(1,4-SiiPr3)2) (1) with the N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene results in intramolecular C–H acti- vation of an isopropyl substituent to form a tucked-in hydride (3). Whilst pyridine will also effect this cyclometallation reaction to form (5), the pyridine analogue of (3), the bases 1,2,4,5-tetramethyl-imid- azole, 2,6-lutidine, DABCO or trimethylphosphine are ineffective. The reaction of (1) with 2,6-dichloro- pyridine affords crystallographically characterised (6) which is the product of oxidative addition of one of the C–Cl bonds in 2,6-dichloro-pyridine across the Ti–Ti double bond in (1). The tucked-in hydride (3) reacts with hydrogen to afford a dihydride complex (4) in which the tuck-in process has been reversed; detailed experimental and computational studies on this reaction using D2, HD or H2/D2 support a mechanism for the formation of (4) which does not involve σ-bond metathesis of H2 with the tucked-in C–H bond in (3). The reaction of (3) with tBuCCH yields the corresponding acetylide hydrido complex (7), where deuteration studies show that again the reaction does not proceed via σ-bond metathesis. Finally, treatment of (3) with HCl affords the chloro-derivative (9) [(NHC)Ti(μ-H)Ti{(μ,η5:η5)Pn†}2Cl], whereas pro- tonation with [NEt3H]BPh4 yielded a cationic hydride (10) featuring an agostic interaction between a Ti centre and an iPr Me group

C-H and H-H activation at a Di-titanium centre

The reaction of the bis(pentalene)dititanium complex Ti2(μ:η5,η5-Pn†)2 (Pn† = C8H4(1,4-SiiPr3)2) with the N-heterocyclic carbene 1,3,4,5 tetramethylimidazol 2 ylidene results in intramolecular C-H activation of one of the iPr methyl groups of a Pn† ligand and formation of a "tucked-in" bridging hydride complex. The "tuck-in" process is reversed by the addition of hydrogen, which yields a dihydride featuring terminal and bridging hydrides

Trimerisation of carbon suboxide at a di-titanium centre to form a pyrone ring system

The reaction of the syn-bimetallic bis(pentalene)dititanium complex Ti2(μ:η5,η5-Pn†)2 (Pn† = C8H4(1,4-SiiPr3)2) 1 with carbon suboxide (O[double bond, length as m-dash]C[double bond, length as m-dash]C[double bond, length as m-dash]C[double bond, length as m-dash]O, C3O2) results in trimerisation of the latter and formation of the structurally characterised complex [{Ti2(μ:η5,η5-Pn†)2}{μ-C9O6}]. The trimeric bridging C9O6 unit in the latter contains a 4-pyrone core, a key feature of both the hexamer and octamer of carbon suboxide which are formed in the body from trace amounts of C3O2 and are, for example, potent inhibitors of Na+/K+-ATP-ase. The mechanism of this reaction has been studied in detail by DFT computational studies, which also suggest that the reaction proceeds via the initial formation of a mono-adduct of 1 with C3O2. Indeed, the carefully controlled reaction of 1 with C3O2 affords [Ti2(μ:η5,η5-Pn†)2 (η2-C3O2)], as the first structurally authenticated complex of carbon suboxide

Salvatora Marzo. Biografia di una guaritrice

Salvatora Marzo is recognized by the community of Nardò as the only female member of the Nardò little orchestra, made up of musician-therapists. Through the percussion of the frame drum this group used to take care of the women suffering from tarantism. The anthropological, autobiographical and visual research is focusing on the entire life story of Salvatora, derived mainly from the memories of her daughter Teresa Errico, enriched with some intervention by the two sisters, Angela and Antonietta

Cu(II) coordination polymers as vehicles in the A³ coupling

A family of benzotriazole based coordination compounds, obtained in two steps and good yields from commercially available materials, formulated [CuII(L 1 )2(MeCN)2]·2(ClO4)·MeCN (1), [CuII(L 1 )(NO3)2]·MeCN (2), [ZnII(L 1 )2(H2O)2]·2(ClO4)·2MeCN (3), [CuII (L 1 )2Cl2]2 (4), [CuII 5(L 1 )2Cl10] (5), [CuII 2(L 1 )4Br2]·4MeCN·(CuII 2Br6) (6), [CuII(L 1 )2(MeCN)2]·2(BF4) (7), [CuII(L 1 )2(CF3SO3)2] (8), [ZnII(L 1 )2(MeCN)2]·2(CF3SO3) (9), [CuII 2(L 2 )4(H2O)2]·4(CF3SO3)·4Me2CO (10) and [CuII 2(L 3 )4(CF3SO3)2]·2(CF3SO3)·Me2CO (11) are reported. These air stable compounds were tested as homogeneous catalysts for the A3 coupling synthesis of propargyl amine derivatives from aldehyde, amine and alkyne under a non-inert atmosphere. Fine-tuning of the catalyst resulted in a one dimensional (1D) coordination polymer (CP) (8) with excellent catalytic activity in a wide range of substrates, avoiding any issues that would inhibit its performance

Ethene activation and catalytic hydrogenation by a low-valent uranium pentalene complex

The reaction of the uranium(III) complex [U(η8-Pn††)(η5-Cp*)] (1) (Pn†† = C8H4(1,4-SiiPr3)2, Cp* = C5Me5) with ethene at atmospheric pressure produces the ethene-bridged diuranium complex [{(η8-Pn††)(η5-Cp*)U}2(μ-η2:η2-C2H4)] (2). A computational analysis of 2 revealed that coordination of ethene to uranium reduces the carbon–carbon bond order from 2 to a value consistent with a single bond, with a concomitant change in the formal uranium oxidation state from +3 in 1 to +4 in 2. Furthermore, the uranium–ethene bonding in 2 is of the δ type, with the dominant uranium contribution being from f–d hybrid orbitals. Complex 2 reacts with hydrogen to produce ethane and reform 1, leading to the discovery that complex 1 also catalyzes the hydrogenation of ethene under ambient conditions

Isolation of a perfectly linear uranium(II) metallocene

Reduction of the uranium(III) metallocene [(η 5 ‐C 5 i Pr 5 ) 2 UI] ( 1 ) with potassium graphite produces the 'second‐generation' uranocene [(η 5 ‐C 5 i Pr 5 ) 2 U] ( 2 ), which contains uranium in the formal divalent oxidation state. The geometry of 2 is that of a perfectly linear bis(cyclopentadienyl) sandwich complex, with the ground‐state valence electron configuration of uranium(II) revealed by electronic spectroscopy and density functional theory to be 5f 3 6d 1 . Appreciable covalent contributions to the metal‐ligand bonds were determined from a computational study of 2 , including participation from the uranium 5f and 6d orbitals. Whereas three unpaired electrons in 2 occupy orbitals with essentially pure 5f character, the fourth electron resides in an orbital defined by strong 7s‐6d z 2 mixing

Pojamide: An HDAC3-selective ferrocene analogue with remarkably enhanced redox-triggered ferrocenium activity in cells.

A ferrocene containing ortho-aminoanilide, N1-(2-aminophenyl)-N8-ferrocenyloctanediamide, 2b (Pojamide) displayed nanomolar potency vs. HDAC3. Compared to RGFP966, a potent and selective HDAC3 inhibitor, Pojamide displayed superior activity in HCT116 colorectal cancer cell invasion assays; however, TCH106 and Romidepsin, potent HDAC1 inhibitors, outperformed Pojamide in cellular proliferation and colony formation assays. Together, these data suggest that HDAC 1 & 3 inhibition is desirable to achieve maximum anti-cancer benefits. Additionally, we explored Pojamide-induced redox-pharmacology. Indeed, treating HCT116 cells with Pojamide, SNP (sodium nitroprusside) and glutathione (GSH) led to greatly enhanced cytotoxicity and DNA damage attributed to activation to an Fe(III) species

Mixed sandwich imido complexes of Uranium(V) and Uranium(IV): Synthesis, structure and redox behaviour

The mixed sandwich U(III) complex {U[η ^8 -C8H6(1,4-Si( iPr)3)2](Cp*)(THF)} reacts with the organic azides RN3 (R = SiMe3, 1-Ad, BMes2) to afford the corresponding, structurally characterised U(V) imido complexes {U[η ^8 -C8H6(1,4-Si( iPr)3)2](Cp*)(NR)}. In the case of R=SiMe3, the reducing power of the U(III) complex leads to reductive coupling as a parallel minor reaction pathway, forming R-R and the U(IV) azide-bridged complex{[U]}2(µ-N3)2, along with the expected [U]=NR complex. All three [U] =NR complexes show a quasi-reversible one electron reduction between -1.6 to -1.75 V, and for R= SiMe3, chemical reduction using K/Hg affords the anionic U(IV) complex K+ {U[η ^8 -C8H6(1,4-Si( iPr)3)2](Cp*)=NSiMe3} - . The molecular structure of the latter shows an extended structure in the solid state in which the K counter cations are successively sandwiched between the Cp* ligand of one [U] anion and the COTtips2 ligand of the next