Complexes [PPh3Cu(Tr(Mes,Me))] (1), [PPh3Cu(Tr(Me,o-Py))] (2), and [PPh3Cu(Br(Mes)pz(o-Py))] (3) (Tr(Mes,Me) = hydrotris[1,4-dihydro-3-methyl-4-mesityl-5-thioxo-1,2,4-triazolyl]borate; Tr(Me,o-Py) = hydrotris[1,4-dihydro-4-methyl-3-(2-pyridyl)-5-thioxo-1,2,4-triazolyl]borate; Br(Mes)pz(o-Py) = hydro[bis(thioxotriazolyl)-3-(2-pyridyl)pyrazolyl]borate; PPh3 = triphenylphosphine) were synthesized by the reaction of dinuclear complexes [Cu(Tr(Mes,Me))]2, [Cu(Tr(Me,o-Py))]2, [Cu(Br(Mes)pz(o-Py))]2, and PPh3. 1-3 were characterized by 1H, 13C, and 31P NMR spectroscopy and ESI-mass spectrometry. Crystal structure analyses were performed for 1 and 2. Both complexes crystallize in the triclinic P space group with the metal in a slightly distorted tetrahedral geometry (S3P coordination) bound by a kappa3-S3 ligand and a PPh3 molecule. The solution molecular structures were investigated by means of variable-temperature (210-310 K, CDCl3, 1-2; 200-310 K, CD2Cl2, 3) and NOESY NMR spectroscopy. The solution structures of 1-2 are in accordance with the X-ray structures, and the complexes do not exhibit fluxional behavior. On the other hand, 3 is subject to an equilibrium between two species with a coalescing temperature of approximately 260 K. DFT geometry optimizations suggest that the major species of 3 consists of the Br(Mes)pz(o-Py) ligand bound to Cu(I) in the kappa3-S2H fashion with two C=S groups and a [Cu...H-B] interaction. A PPh3 completes the copper coordination (S2HP coordination). The complex [TuCu(Tr(Mes,Me))] (4) (Tu = thiourea) was crystallized using an excess of Tu with respect to [Cu(Tr(Me,2-Py))]2 (approximately a 6:1 ratio). The metal adopts a distorted tetrahedral geometry with an overall S3H coordination determined by the bound kappa3-S2H ligand (two C=S groups and a [B-H...Cu] interaction) and by a Tu. The reactivity of dinuclear complexes [Cu(Tr(Mes,Me))]2, [Cu(Tr(Me,o-Py))]2, and [Cu(Br(Mes)pz(o-Py))]2 with monodentate ligands was investigated by means of NMR titrations with PPh3, Tu. and pyridine (Py), and formation constants for the adducts [DCu(L)] (D = monodentate donor, L = tripodal ligand) were determined.

The aim of the present study was the synthesis, the determination of formation constants, and the evaluation of the antiproliferative activity of two copper(II) complexes formed with triazole-type ligands. The synthesis of the unsymmetrical triazole ligand 4-amino-3-aminomethyl-5-methyl-1,2,4-triazole (L1), and its copper(II) complex is reported. The ligand was prepared by functionalization of the carboxylate function of tert-butyloxycarbonyl (BOC) protected glycine O-methyl ester. All intermediates and final products were isolated and characterized with IR, 1H NMR, and elemental analysis. X-ray structures of the ligand as a sulfate salt ((H2L1)2SO4 · H2O) and the copper(II) complex [CuCl2(L1)2] are described. The ligand forms a (N,N) bidentate chelate with the amino group and one triazole nitrogen atom. The tetragonally distorted octahedral coordination of CuII results from two axially coordinated chloride ions. Protonation constants for L1 and speciation of the CuII/L1 system were determined in 0.1 M aqueous KCl solution at 25 °C. Complexes formed in solution were also characterized by visible spectrophotometry. Ligand substitution competition between L1 and glycine has also been studied using potentiometric titrations. Antiproliferative activities of ([CuCl2(L1)2]) and [CuCl2(H2L2)]Cl, where HL2 is the 5-thioxo analog of L1, against human tumor cell lines HT1080 and HT29 as well as normal human fibroblasts (HF) are presented along with the antiproliferative activities of L1, CuCl2, and cisplatin. Activity of these two complexes are discussed and compared with the activity of analogous compounds reported in the literature which contain pyridyl groups in place of the aminomethyl group. In particular, it is suggested that a lypophilic residue such as a pyridyl group is important for antiproliferative activity of this class of compounds.

The disubstituted cyclopentadiene C5H4(SiMe2Cl)[SiMe2(CH2CH=CH2)] was isolated by reaction of the lithium salt [Li{C5H4SiMe2(CH2CH=CH2)}] with SiMe2Cl2. It was then treated with NH(2)tBu and LiNH(2,6-Me2C6H3) to give the (ammosilyl)cyclopentadienes C5H4[SiMe2(CH2CH=CH2)-[SiMe2(NHR)], which were further deprotonated to their dilithium salts [Li-2{1-SiMe2NR-3-SiMe2(CH2CH=CH2)C5H3}] (R = tBu, 2,6-Me2C6H3). Reactions of the metal halides ZrCl4(THF)(2) and HfCl4 with these dilithium salts, followed by alkylation of the resulting dichloro complexes, afforded the (eta(1)-amidosilyl) eta(5)-cyclopentadienyl complexes [M{eta(5)-C5H3(SiMe2-eta(1)-NR)[SiMe2(CH2CH=CH2)]}X-2] (R = tBu, 2,6-Me2C6H3; X = Cl, Me, CH2Ph; M = Zr, Hf). Only the bis(iminoacyl) complexes [M{eta(5)-C5H3(SiMe2-eta(1)-NtBu)[SiMe2(CH2CH=CH2) ]}{eta(2) -CR=N(2,6-Me2C6H3)}(2)] (M = Zr, Hf; R = Me, CH2Ph) could be isolated when the dialkylzirconium and -hafnium complexes were treated with CN(2,6-Me2C6H3); these were slowly transformed into the C-C-coupled diazametallacyclopentene compounds [M{eta(5)-C5H3 (SiMe2-eta(1)-NtBu) [SiMe2 (CH2CH=CH2)]}{eta(1)-N(2,6-Me2C6H3)-CR=CR-eta(1)-N(2,6-Me2C6H3)}] (R = Me, CH2Ph, M = Zr; R = Me, M = Hf) when their toluene solutions were heated to 70 degrees C-80 degrees C for long periods (2-4 d). The structural characterisation of all of the new compounds is described and the molecular structure of the dimeric dichlorozirconocene [ZrCl(mu-Cl)[eta(5)-C5H3(SiMe2-eta(1)-NtBu)[SiMe2(CH2CH=CH2)]}](2), was determined by X-ray diffraction methods. (c) Wiley-VCH Verlag GmbH & Co.

Dinuclear Cu(I) complexes with bifunctionalized homoscorpionate ligands, hydrotris(thioxotriazolyl)borato [Li(Tr(Me,o)(-)(Py)) (1) and Li(Tr(Mes,Me)) (2)], and the heteroscorpionate ligand hydro[bis(thioxotriazolyl)-3-(2-pyridyl)pyrazolyl]borato [K(Br(Mes)pz(o)(-)(Py))] (3) were synthesized and crystallographically characterized. The complexes [Cu(Tr(Mes,Me))](2) (4) and [Cu(Tr(Me,o)(-)(Py))](2) (5) exhibit a similar coordination geometry where every metal is surrounded by three thioxo groups in a trigonal arrangement. The presence of a [B-H...Cu] three-center-two-electron interaction in both compounds causes the overall coordination to become tetrahedrally distorted (S(3)H coordination for each metal). The complex [Cu(Br(Mes)pz(o)(-)(Py))](2) (6) presents a trigonal geometry in which the metals interact with two thioxo groups and a bridging pyrazolyl nitrogen atom. A weak contact with a pyridine nitrogen atom completes the coordination of the metals (S(2)N,N' coordination for each metal). [Cu(Tr(Mes,Me))](2), [Cu(Tr(Me,o)(-)(Py))](2), and [Cu(Br(Mes)pz(o)(-)(Py))](2) exhibit fluxional behavior in solution as evidenced by variable-temperature NMR spectroscopy, and for 5 and 6 two species in equilibrium [in the ratio 2/1 for 5 (CDCl(3)) and 3/2 for 6 (CD(2)Cl(2))] are distinguishable in the (1)H NMR spectra at 270 K. 2D-NOESY spectra recorded at 270 K assisted in the attribution of solution molecular geometries for each isomer of 5 and 6. The free energy of activation (DeltaG()(Tc)) was determined for both equilibria from the evaluation of the coalescence temperature. DFT calculations were performed to describe plausible molecular geometry for the minor isomer of 5 and 6 and to propose a possible mechanism of interconversion between major and minor isomers. Cyclic voltammograms were recorded in CH(2)Cl(2) (3 and 6) or CH(2)Cl(2)/CH(3)CN (1/1, v/v) (2, 4, and 5) solutions using 0.1 M TBAHFP or TBAOTf as supporting electrolytes. [Cu(Tr(Mes,Me))](2), [Cu(Tr(Me,o)(-)(Py))](2), and [Cu(Br(Mes)pz(o)(-)(Py))](2) exhibit a quasi-reversible Cu(I)/Cu(II) redox behavior with E(pa) = +719 mV and E(pc) = +538 mV for 4, E(pa) = +636 mV and E(pc) = -316 mV for 5, and E(pa) = +418 mV and E(pc) = -319 mV for 6.

Two new sulfurated triazoline ligands have been synthesized by functionalization of glycine and L-alanine (HL1 and HL2 respectively) at the carboxylate site with retention of chirality in the latter case. The ligands and their copper(II) complexes have been characterized by spectroscopic methods and their structures were determined by X-ray diffraction. The compound [CU(H2L2)(2)]-(H5O2)(SO4)(2)(HSO4) presents a very disordered structure with regard to the anionic counterion and a very unusual elongated crystal cell. In all the complexes the ligands are (N,S) coordinated to copper(II), while the amino groups remain protonated and uncoordinated. The ligands have also been studied in solution and their dissociation constants were determined both by potentiometry and H-1 NMR titrations. Potentiometric studies on the complex [Cu(H2L2)(2)](H5O2)(SO4)(2)(HSO4) were performed to determine the dissociation constants of the ligand once coordinated to the metal. The complex [CUCl2(H2L1)]Cl was studied also by magnetic susceptibility measurements, showing an interesting antiferromagnetic behavior at low temperature which has been interpreted on the basis of its crystal packing. (C) 2004 Elsevier B.V. All rights reserved.

The complex [Ni(Tr-Me,Tr-o-PY)(2)] (2) {Tr-Me,Tr-o-Py = hydrotris[1,4-dihydro-4-methyl-3-(2-pyridyl)-5-thioxo-1,2,4-triazolyl]borate} was synthesized and characterized by UV-Vis spectroscopy, ESI-mass spectrometry and X-ray crystallography. Complex 2 crystallizes in the tetragonal I-42d space group. The metal presents a slightly distorted octahedral geometry (N4S2 co-ordination) bound by two ligands that behave in the S,NIN' co-ordination mode: one of the three arms of each tripod is bound to the metal with the thioxo group, the second chelates NIN' with the triazoline and pyridine nitrogen atoms and the third does not participate in the metal coordination. Ni/Tr-Me,Tr-o-Py complexation was studied by collecting visible spectra of 16 batch samples (10 ml) containing a fixed concentration of metal (9.994 x 10(-4) mol dm(-3)) with increasing concentrations of ligand up to Ni/L = 1/3 (L = Tr-Me,Tr-o-Py). For a Ni/L ratio of 1/2, approximate to38% of NiL+ and approximate to56% of NiL2 are present with respect to the total Ni(H) concentration. Conductivity (Lambda(M) range 112-55 ohm(-1) cm(2) mole(-1) in acetonitrile and Lambda(M) range 15-8 ohm(-1) cm(2) mole(-1) in DMF) and ESI-mass spectrometry results are consistent with a partial dissociation of 2 in acetonitrile and DMF solutions according to the equilibrium NiL2 = NiL+ + L- in agreement with the spectrophotometric titration results. Cyclic voltammetry performed on acetonitrile solutions of 2 reveals the electrochemical activity of the Tr-Me,Tr-o-Py ligand, which undergoes irreversible oxidation and reduction processes at potential > +0.7 and similar to0 V, respectively. The occurrence of the Ni(II)/Ni(III) and Ni(II)[Ni(l) electrochemical events could not be determined. (C) 2004 Elsevier Ltd. All rights reserved.

Preparations of copper(I) and bismuth(III) complexes of hydrotris(4-ethyl-3-methyl-5-thioxo-1,2,4-triazolyl)borate (Tr(Et,Me)) are described. These complexes have been characterized by means of spectroscopy and microanalysis. Molecular structures of [Cu(Tr(Et,Me))](2) x 2.5CH(3)CN x 0.5H(2)O (3a) and [Bi(Tr(Et,Me))(2)]NO(3) x 2CHCl(3) (4a) have been determined by single-crystal X-ray diffraction. In the centrosymmetric dimeric copper(I) complex, Tr(Et,Me) acts in the k(3)S,S',H:kS' ' coordination mode. The metal is found in a distorted trigonal geometry as the ligand exhibits an "S(3)-inverted" conformation at the boron center so that a weak [B-H.Cu] agostic interaction renders the overall coordination of the (3 + 1) type. On the other hand, in the bismuth complex, Tr(Et,Me) presents the k(3)S,S',S' ' coordination mode and the "S(3)-normal" conformation. The metal is found in a regular octahedral geometry bound by six thioxo groups of two ligands. Species distributions in solution have been studied using electrospray ionization mass spectrometry upon dissolution of 3a and 4a crystals in acetonitrile. Monomeric and polynuclear copper(I) complexes with different M:L ratios are present in solution, while for 4a only the monomeric species is present.

Reacting the heterocycle 5-thioxo-1,4-dihydro-4-ethyl-3-methyl-1,2,4-triazole (thioxotriazoline) with sodium tetrahydroborate in the molar ratio of approximately 2:1 at 130 degrees C provides the new ligand dihydrobis(thioxotriazolinyl)borato, [Bt(Et,Me)](-), as its sodium salt. The neutral complexes of this anionic ligand with zinc(II), bismuth(III), and nickel(II) have been synthesized and characterized by X-ray crystallography. In every complex, the ligand is coordinated to the metal in the S(2) mode, generating eight-membered chelate rings. The bismuth and nickel complexes exhibit two M.H-B interactions responsible for the dodecahedral and octahedral geometries, respectively. For the zinc complex, the trigonal-bipyramidal coordination is achieved with an apical Zn.H-B interaction. The crystal structures for the three complexes are described, and ab initio calculations on Bi(III), Ni(II), and Zn(II) compounds have been performed in order to assess the nature of the M.H-B interaction and its role for the definition of the molecular geometries.

The ligand hydrotris (1,4-dihydro-3-methyl-4-phenyl-5-thioxo-1,2,4-triazolyl)borato (Tr-Ph,Tr- Me) was synthetized as natrium salt and the complexes [Zn(Tr-Ph,Tr-Me)(2)] (.) 7.5H(2)O (.) 1.5CH(3)CN (2a), [Zn(Tr-Ph,Tr-Me)(2)]. 8DMF (2b), [Co(Tr-Ph,Tr-Me)(2)] (.) 8DMF (3a), [Ni(Tr-Ph, (Me))(2)] (.) H2O (.) 6DMSO (4a), [Bi(Tr-Ph,Tr-Me)(2)]NO3 (5), have been isolated and structurally characterized by X-ray diffraction. In the zinc derivatives the ligand adopts different denticity and coordination modes, eta(2) and [S-2] for 2a and eta(3) and [N-3] for 2b, depending on the crystallization solvent, giving rise to tetrahedral and octahedral geometry, respectively. In the octahedral cobalt and nickel complexes the ligand is eta(3) and [N-3] coordinated whereas in the bismuth complex the eta(3) and [S-3] coordination is exhibited.

The (amido)methyl complexes [Ta(η5-C5Me5)(NtBu)Me(NR2)] [R = Ph (3), SiMe3 (4)] were prepared by reaction of [Ta(η5-C5Me5)(NtBu)ClMe] (1) with the appropriate lithium amides. Attempts to isolate the analogous NHMe derivative afforded a mixture of complexes [Ta(η5-C5Me5)(NtBu)Me(NHMe)] (5) and [Ta(η5-C5Me5)(NMe)Me(NHtBu)] (6), resulting from hydrogen exchange between the amido and imido ligands. Insertion of CN(2,6-Me2C6H3) into the Ta−Me bond of complexes 3 and 4 gave the η1-iminoacyl derivatives [Ta(η5-C5Me5)(NtBu)(NR2){η1-C(Me)=N(2,6-Me2C6H3)}] [R = Ph (7), SiMe3 (8)], while insertion into the Ta−NRMe (R = H, Me) bond of the complexes [Ta(η5-C5Me5)(NtBu)Me(NRMe)] [R = H (5), Me (2)] gave the η2-iminocarbamoyl compounds [Ta(η5-C5Me5)(NtBu)Me{η2-C(NRMe)=N(2,6-Me2C6H3)}] [R = H (10), Me (9)]. All of the new compounds were characterized by 1H and 13C NMR spectroscopy. The X-ray crystal structure of 9 is reported. DFT calculations were carried out to justify the preference of the insertion either into the Ta−C or the Ta−N bond. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

The reaction of the complex [Ni(Bu(2)timdt)(2)](Bu(2)timdt = -1 charged 1,3-dibutylimidazolidine-2,4,5-trithione) with polyfunctional phosphines: tp [tp = bis(2-diphenylphosphinophenyl) phenylphosphine] and qp [qp = tris(2-diphenylphosphinophenyl) phosphine] produces [Ni(tp)(Bu(4)btimdt)] (1) and [Ni(qp)(Bu(4)btimdt)] (2), respectively. X-Ray crystallographic studies show that in both complexes, the nickel ion is coordinated in a trigonal bipyramidal geometry with three P-atoms of the tp and of qp (one of the 'arms' of qp is non-coordinating) ligands occupying three facial sites and with two sulfur atoms of Bu(4)btimdt [5,5'-bis(1,3-dibutyl-4-imidazolidine-2-thione-4-thiolate)]. This new S,S dinegative chelating ligand is generated in situ by desulfurisation of one of the two vicinal sulfur atoms on each ligand in [Ni(Bu(2)timdt)(2)] and C-C coupling between the two imidazole rings. The Bu(4)btimdt anion is chiral, as free rotation about the C-C bond between the two imidazole rings is hindered by high energy barriers. No desulfurisation is observed when reacting Bu4N[Ni(dmit)(2)] with tp, and the obtained product is [Ni(tp)(dmit)] (3), a nickel complex where the metal is still coordinated with a trigonal bipyramidal geometry (three P-atoms of the tp ligand and two sulfur atoms of the dmit ligand).

Preparations of copper(II) and palladium(II) complexes of 4-amino-5-methylthio-3-(2-pyridyl)-1,2,4-triazole (L1) and the copper(II) complex of 1,4-dihydro-4-amino-3-(2-pyridyl)-5-thioxo-1,2,4-triazole (HL) are described. These complexes have been characterized by means of spectroscopy and microanalysis. Molecular structures of HL (1), [CuCl2(H2L)]Cl·2H2O (2a), cis-[CuCl2(L1)] (3), and cis-[PdCl2(L1)] (4) have been determined by single-crystal X-ray diffraction. The HL ligand acts as a N,S bidentate through the thioxo moiety and the exo-amino group whilst the ligand L1 forms N,N coordination complexes through the pyridine and triazole nitrogen atoms. Speciation in solution of the systems Cu/HL and Cu/L1 have been determined by means of potentiometry and spectrophotometry as well as for the Cu/L1/A (HA=glycine) system in order to determine species present at physiological pH. Antiproliferative activity of these complexes and their ligands was evaluated, using the AlamarBlue™ Assay, on normal human fibroblasts (HF) and human fibrosarcoma tumor (HT1080) cells. The copper compounds cis-[CuCl2(H2L)]Cl and cis-[CuCl2(L1)] exerted significant antiproliferative activity of both normal and neoplastic cells; although dose–response experiments revealed that the HT1080 cell line was more sensitive to the tested drugs than normal fibroblasts.

The synthesis, X-ray structure, magnetic and transport properties of the compound Ni(dmf)6[Ni(dsit)2]2 (dmf=dimethylformamide, dsit=1,3-dithiole-2-thione-4,5-diselenolate) are described. This compound crystallizes in the monoclinic space group P21/c, with a=18.709(6), b=22.975(5), c=20.418(5) Å, β=99.31(2)° and Z=6; its structure consists of [Ni(dsit)2]22− dimers and isolated [Ni(dmf)6]2+ cations both centrosymmetric and non-centrosymmetric. The dimers are packed forming chains along the [101] direction with short Se·Se interdimer contacts. Additional interchains S·S contacts render this structure a three-dimensional character, never observed so far in other [Ni(dsit)2]− salts. This compound exhibits semiconducting behavior with a room temperature conductivity (1 S cm−1) much higher than those reported for other salts of the [Ni(dsit)2]− anion. Tight-binding band structure calculations were used to analyze the origin of the semiconducting properties of this salt. The magnetic susceptibility shows Curie behavior with C=1.25 emu K mol−1, typical of isolated Ni(II) ions as expected for the octahedrally coordinated [Ni(dmf)6]2+ cations.

New [M(R(2)pipdt)(2)](BF(4))(2) salts [R(2)pipdt = N,N'-dialkyl-piperazine-2,3-dithione; M = Pd(II), R = Me and M = Pt(II), R = Me, Et, Pr(i)] bearing redox-active cationic dithiolene complexes have been prepared and characterized. These cations react with the redox-active [M(mnt)(2)](2-) [M = Pd(II), Pt(II); mnt = maleonitrile-2,3-dithiolate] anionic dithiolenes to form salts describable as ion pair charge-transfer complexes. X-ray crystallographic studies have shown that [M(Me(2)pipdt)(2)][M(mnt)(2)] complexes, with M = Pd(II) and Pt(II), are isomorphous. Crystal data of the Pt salt (3a): triclinic, Ponemacr; (No. 2); Z = 1; T = 293(2) K; a = 6.784(7) A, b = 8.460(6) A, c = 13.510(5) A, alpha = 100.63(2) degrees, beta = 104.04(2) degrees, gamma = 96.90(2) degrees; R1 = 0.0691 [wR2 = 0.2187 (all data)]. Structural data show that approximately square-planar [Pt(Me(2)pipdt)(2)] dications and regular square-planar [Pt(mnt)(2)] dianions form an infinite anion-cation one-dimensional stack along axis a with a Pt...Pt a/2 distance of 3.392 A and a Pt...Pt...Pt angle of 180 degrees. Anions and cations arrange themselves face-to-face so as to take on a staggered arrangement. These salts exhibit strong absorptions in the visible-near-infrared region assigned to ion pair charge-transfer transitions. A relation between the optical and thermal electron transfer in the solid state is obtained using a "Marcus-Hush model", and a solid-state electrical conductivity in agreement with expectations is observed. Vibrational spectroscopy is in agreement with the existence of charge-transfer interactions between the cationic and anionic components of the salts.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTN,N'-Dimethylpiperazinium-2,3-dithione Triiodide, [Me2Pipdt]I3, as a Powerful New Oxidation Agent toward Metallic Platinum. Synthesis and X-ray Structures of the Reagent and the Product [Pt(Me2Pipdt)2](I3)2Francesco Bigoli, Paola Deplano, Maria Laura Mercuri, Maria Angela Pellinghelli, Gloria Pintus, Angela Serpe, and Emanuele F. TroguView Author Information Dipartimento di Chimica Inorganica ed Analitica Università di Cagliari, Cittadella di Monserrato I-09042 Monserrato, Cagliari, Italy Cite this: J. Am. Chem. Soc. 2001, 123, 8, 1788–1789Publication Date (Web):February 3, 2001Publication History Received12 September 2000Published online3 February 2001Published inissue 1 February 2001https://pubs.acs.org/doi/10.1021/ja0056015https://doi.org/10.1021/ja0056015rapid-communicationACS PublicationsCopyright © 2001 American Chemical SocietyRequest reuse permissionsArticle Views478Altmetric-Citations33LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (3)»Supporting Information Supporting Information SUBJECTS:Adducts,Gold,Layers,Metals,Reagents Get e-Alerts

Doubly bridged di(silyl-η-amido)cyclopentadienyltitanium and -zirconium complexes and their related cations as the [(PhCH2 )B(C6 F5 )3 ]- salts have been isolated (see structure of the Ti derivative). The neutral benzylzirconium complex was a very efficient catalyst in the presence of methylaluminoxane for producing high molecular weight polyethylene and ethylene-1-hexene copolymers.

A simple method to obtain in high yields mixed-ligand nickel-dithiolene complexes, which show strong negative solvatochromism and negative first molecular hyperpolarizability, and the use of Raman spectroscopy to establish the extent of electronic delocalisation in these complexes, are reported.

The imido-amido complex [TaCp*((NBu)-Bu-t)Cl((NHBu)-Bu-t)], 1, was isolated from the reaction of [TaCp*XCl4] with 3 equiv of (LiNHBu)-Bu-t. The dimethyl [TaCp*((NBu)-Bu-t)Me-2], 2, and chloro-methyl [TaCp*((NBu)-Bu-t)ClMe], 3, complexes were obtained by methylation of [TaCp*((NBu)-Bu-t)Cl-2] with 2 equiv of LiMe and 1 equiv of ZnMe2, respectively. Metathetical reactions of complex 3 with alkali metal salts MX (M = Na, X = OMe; M = Li, X = (OBu)-Bu-t, NHtBu) afforded the new imido-methyl compounds [TaCp*((NBu)-Bu-t)MeX] (X = OMe 4, (OBu)-Bu-t 5, (NHBu)-Bu-t 6). Insertion of CNR (R = 2,6-Me2C6H3) into the Ta-(NHBu)-Bu-t and Ta-Me bonds of the imido-pentamethylcyclopentadienyl complexes 1-6 gave the eta(2)-iminocarbamoyl compound [TaCp*((NBu)-Bu-t)Cl{eta(2)-C((NHBu)-Bu-t)=NR}], 7, and the eta(2)-iminoacyl compounds [TaCp*((NBu)-Bu-t)X(eta(2)-C(Me)=NR}] (X = Me 8, Cl 9, OMe 10, (OBu)-Bu-t 11, (NHBu)-Bu-t 12), which under appropriate thermal conditions react with a second equivalent of CNR (R = 2,6-Me2C6H3) to give the double insertion imine-eta(2)-iminoacyl products [TaCp*((NBu)-Bu-t)X{eta(2)-C[C(Me)=NR]=NR}] (X = Me 13, Cl 14, OMe 15, (OBu)-Bu-t 16, (NHBu)-Bu-t 17). When compound 17 was heated at 140 degrees C for 3 days, an intramolecular proton migration occurred to give the eta(2)-diamidoalkene complex [TaCp*((NBu)-Bu-t){eta-(NBu)-Bu-t-C(NHR)=C(Me)-eta-NR}], 18. All of the new compounds were characterized by IR, H-1 NMR; and C-13 NMR spectroscopy, and the molecular structures of 14 and 18 were studied by X-ray diffraction methods.