Dalton Transactions

doi: 10.1039/c002807jpmid: N/A

doi: 10.1039/c002808hpmid: N/A

Solomon, Sophia A.; Layfield, Richard A.

doi: 10.1039/b918619kpmid: 20179837

Metal allyl complexes in which the ligands carry bulky silyl substituents frequently show stability that cannot be achieved with unsubstituted analogues. As a result, it has been possible to characterize a large family of structurally diverse metal silyl-allyls from the s-, p-, d- and f-blocks of the Periodic Table, and to study the coordination chemistry of compounds that often have no counterparts without bulky substituents. The fact that the majority of compounds discussed in this Perspective have been published since 2000 reflects the newness of the area, and the article summarizes the main developments in the structural chemistry of metal silyl-allyls and also selected synthetic and catalytic applications. Although organometallic chemistry is often regarded as transcending traditional boundaries between ‘organic’ and ‘inorganic’ chemistry, an understanding persists that those working in the field can be labelled ‘inorganic organometallic’ chemists or ‘organic organometallic’ chemists. It is hoped that chemists from a broad range of backgrounds will be able to use this review as an entry point to an exciting new direction in metal allyl chemistry.

Zhang, Haitao; Yang, Jen-Hsien; Dikarev, Evgeny V.

doi: 10.1039/b925952jpmid: 20179838

The potential of fluorinated tetraolate as a ligand for the synthesis of polynuclear metal complexes has been demonstrated.

Zhang, Jian; Chen, Shumei; Bu, Xianhui

doi: 10.1039/b925714dpmid: 20179839

Reported here is an organic-cation templated 4-connected anionic boron imidazolate framework [N(CH3)4][Cd(SH)2B(im)4] (ABIF-1, im = imidazolyl), which is synthesized from the reaction of the supertetrahedral Cd10S4(SPh)12 cluster with [N(CH3)4]Cl and NaB(im)4. The work represents an important step in the expansion of boron imidazolate frameworks from neutral BIFs to anionic ABIFs.

Shi, Shuo; Zhao, Juan; Geng, Xiaoting; Yao, Tianming; Huang, Hailiang; Liu, Tianlin; Zheng, Lengfeng; Li, Zonghui; Yang, Danjing; Ji, Liangnian

doi: 10.1039/b916094apmid: 20179840

[Ru(phen)2(dppz)]2+can serve as a prominent molecular “light switch” for G-quadruplexes and i-motif, but it preferentially binds to G-quadruplexes over i-motif.

Tourneux, Jean-Christophe; Berthet, Jean-Claude; Thuéry, Pierre; Mézailles, Nicolas; Le Floch, Pascal; Ephritikhine, Michel

doi: 10.1039/b926718mpmid: 20179841

Metathesis reactions of UCl4 with Li2C(Ph2PS)2 in Et2O only afforded the tris-carbene complex [{Li(OEt2)}2U{C(Ph2PS)2}3] (1), while the bis- and mono-carbene compounds [U{C(Ph2PS)2}2(THF)2] (2) and [{Li(THF)2}2U{C(Ph2PS)2}Cl4] (3) were obtained by treatment of UCl4 with Li2C(Ph2PS)2 in a mixture of THF and toluene. The bis-carbene complex 2 was also obtained either from the comproportionation reaction of 1 and UCl4 or protonolysis reaction of U(NEt2)4 with H2C(Ph2PS)2 and was transformed into the mono-carbene complex [U{C(Ph2PS)2}Cl2(THF)2] (4) by further reaction with UCl4. The utility of these complexes as precursors is illustrated by the synthesis of the biscyclopentadienyl derivative [Cp2U{C(Ph2PS)2}] (5) by treatment of 3 with TlCp. The crystal structures of [U{C(Ph2PS)2}2(py)2]·1.5py·0.5THF and 5·toluene are reported.

Deng, Yuanfu; Lv, Qiying; Wu, Songping; Zhan, Shuzhong

doi: 10.1039/b920987epmid: 20179842

Three isostructural heterobimetallic nitrilotriacetatoperoxotitanate complexes of general formula [M(H2O)5]2[Ti2(O2)2O(nta)2]·7H2O [M = Co (1), Ni (2) and Zn (3)] have been isolated in pure crystals directly from the quaternary system of M2+–Ti(OC4H9)4–H2O2–H3nta (H3nta = nitrilotriacetic acid) at pH = 4.0 and have been characterized by elemental analyses, IR, thermal analysis (TGA), and single-crystal X-ray diffraction. Single crystal X-ray analysis reveals that the titanium atom in these complexes features seven-fold-coordination, each surrounded by six oxygen atoms and one nitrogen atom. The divalent transition metal ions in these compounds are hexa coordinated, surrounded by five water molecules and one bridged carboxylato oxygen atom. The TGA and XRD results prove that complexes 1–3 undergo facile thermal decomposition to form pure CoTiO3, NiTiO3 and ZnTiO3 at 700 °C respectively. The morphologies, microstructures, and crystallinity of the residues obtained after pyrolysis were characterized by transmission electron microscopy and powder X-ray diffraction.

Wikstrom, Jeffrey P.; Filatov, Alexander S.; Mikhalyova, Elena A.; Shatruk, Michael; Foxman, Bruce M.; Rybak-Akimova, Elena V.

doi: 10.1039/b916832jpmid: 20179843

The tridentate aminopyridine ligand bearing a bulky tert-butyl substituent at the amine nitrogen, tert-butyl-dipicolylamine (tBuDPA), occupies three coordination sites in six-coordinate complexes of nickel(ii), leaving the remaining three sites available for additional ligand binding and activation. New crystallographically characterized complexes include two mononuclear species with 1:1 metal:ligand complexation: a trihydrate solvate (1·3H2O) and a monohydrate biacetonitrile solvate (1·H2O·2CH3CN). Complexation in the presence of sodium hydroxide results in a bis(μ-hydroxo) complex (2), the bridging hydroxide anions of which are labile and become displaced by methoxide anions in methanol solvent, affording bis-methoxo-bridged (4). Nickel(ii) centers in 2 are five-coordinate and antiferromagnetically coupled (with J = −31.4(5) cm−1, Ĥ = −2JŜ1Ŝ2, in agreement with Ni–O–Ni angle of 103.7°). Bridging hydroxide or alkoxide anions in coordinatively unsaturated dinuclear nickel(ii) complexes with tBuDPA react as active nucleophiles. 2 readily performs carbon dioxide fixation, resulting in the formation of a bis(μ-carbonato) tetrameric complex (3), which features a novel binding geometry in the form of an inverted butterfly-type nickel-carbonate core. Temperature-dependent magnetic measurements of tetranuclear carbonato-bridged 3 revealed relatively weak antiferromagnetic coupling (J1 = −3.1(2) cm−1) between the two nickel centers in the core of the cluster, as well as weak antiferromagnetic pairwise interactions (J2 = J3 = −4.54(5) cm−1) between central and terminal nickel ions.

Dash, Chandrakanta; Shaikh, Mobin M.; Butcher, Ray J.; Ghosh, Prasenjit

doi: 10.1039/b917892apmid: 20179844

A comparison is drawn between the nickel and palladium precatalysts of 1,2,4-triazole based N-heterocyclic carbenes in the hydroamination of activated olefins. Though all of the newly designed nickel and palladium precatalysts, trans-[1-i-propyl-4-R-1,2,4-triazol-5-ylidene]2MBr2 [R = Et, M = Ni (1b); R = Et, M = Pd (1c); R = CH2CHCH2, M = Ni (2b) and R = CH2CHCH2, M = Pd (2c)], are moderately active for hydroamination reaction of a variety of secondary amines viz. morpholine, piperidine, pyrrolidine and diethylamine with activated olefins like, acrylonitrile, methyl acrylate, ethyl acrylate and t-butyl acrylate at room temperature in 1 hour, the nickel complexes (1b and 2b) exhibited superior activity compared to its palladium counterparts (1c and 2c). The better performance of the nickel complexes has been correlated to the more electron deficient metal center in the nickel 1b and 2b complexes than in the palladium 1c and 2c analogs based on the density functional theory studies. The 1b-c and 2b-c complexes were synthesized by the reaction of 1-i-propyl-4-R-1,2,4-triazolium bromide [R = Et (1a) and R = CH2CHCH2 (2a)] with MCl2 [M = Ni, Pd] in presence of NEt3 as a base.