Mononuclear Transition Metal Complexes Research Articles

Carbonyl Transition Metal Complexes of a Silaborate Ligand

Reaction between three equivalents of the silaborate [NEt4][MeSiB10H12] (2) and one equivalent of [Ru3(CO)12] resulted in almost quantitative formation of the mononuclear transition metal complex [NEt4][Ru(CO)3(η5-MeSiB10H10)] (5), which was characterized by X-ray structure analysis. The trinuclear ruthenium complex [NEt4][Ru3(CO)8(η5-MeSiB10H10)] (7) was synthesized in high yield from the reaction of one equivalent of 2 and [Ru3(CO)12]. The cluster 7 reacts with two equivalents of PMe2Ph with substitution of two carbonyl groups to give the substitution product [NEt4][Ru3(CO)6(PMe2Ph)2(η5-MeSiB10H10)] (8).

Mono- and Bi-nuclear Complexes of the Doubly Bidentate, Bridging Ligand 4,6-Di(2-pyridyl)pyrimidine.

Thirteen mononuclear, homobinuclear and heterobinuclear transition metal complexes of 4,6-di(2- pyridyl)pyrimidine have been prepared. Assignments of the 1H n.m.r. spectra of the molybdenum(0) and ruthenium(II) complexes were achieved by a combination of one- and two-dimensional n.m.r. techniques, especially 1D-TOCSY. For the ruthenium complexes, electronic absorption spectroscopy and cyclic voltammetry were used to probe the nature of the metal{ligand and, for the binuclear complexes, metal-metal interactions. The complexes have low HOMO−LUMO energy gaps. Meta-metal interactions are shown to be of similar magnitude to those in complexes of the better-studied ligands 2,2′-bipyrimidine and 2,3-di(2-pyridyl)pyrazine.

Mössbauer and magnetic properties of mononuclear, homo- and hetero-dinuclear complexes

A series of mononuclear, homo- and hetero-dinuclear transition metal complexes with compartmental, potentially hexadentate, Schiff bases has been synthesized and characterized by IR, Mössbauer and magnetic measurements. The mononuclear and homo-dinuclear complexes have been obtained by reaction of the preformed ligands, derived by the condensation of 2,3-dihydroxy-benzaldehyde and, respectively, 1,2-diaminoethane (H 4L A), 1,2- diamino-2-methylpropane (H 4L B), 1,3-diamino-2,2-dimethylpropane (H 4L C) or 1,2-diaminobenzene (H 4L D) with the appropriate metal salts, or by template condensation of the formyl and the appropriate amine precursor. The hetero-dinuclear complexes have been obtained by reaction of the mononuclear complexes with the desired metal salt, in the presence of base. By using iron(II) acetate, mononuclear and homo-dinuclear iron(III) complexes have also been prepared. Mononuclear, homo- and hetero-dinuclear complexes have also been prepared for the ligands obtained by reaction of ethylenediamine with 3-methoxy (H 2L E) or 3 ethoxy-salicylaldehyde (H 2L F), respectively. For the iron-containing compounds, the site occupancy, the oxidation state of the metal ion and the coordination geometry were verified by Mössbauer spectroscopy. The Mössbauer effect parameters of the mononuclear complexes are typical for octahedral high-spin iron(III) derivatives containing a single iron site. The presence of substituents on the ligand does not affect the isomer shift values, while it has a marked influence on the quadrupole splitting. Its value increases from 0.77 mm/s for the complex with H 4L B to 0.98 mm/s for the derivative with H 4L D. In the same way for the hetero-dinuclear compounds containing copper(II)-iron(II1) and nickel(II)-iron(III) ions, the δ values do not change while large differences are evident in the quadrupole splitting. The Mössbauer spectra of the homo-dinuclear complexes exhibit a doublet with a large linewidth that can only be fit as a superimposition of two different doublets, one inside the other. The parameters obtained for the inner and the outer doublet are very similar to those of the mononuclear and of the hetero-dinuclear derivatives, respectively. In the di-iron derivative with the ligand H 4L D, the outer iron is only partially oxidized, and variable amounts of a distorted octahedral high-spin iron(II) species can always be detected in the Mössbauer spectra. The magnetic properties of this class of complexes have been studied. In particular the magnetic susceptibility of the mononuclear Fe, homodinuclear Fe 2, heterodinuclear CuFe and CuMn derivatives have been measured down to 2.5 K and analyzed by means of appropriate models. The coupling for the dinuclear compounds was found to be antiferromagnetic in nature.

Spin coupling in iron-containing proteins and model complexes

In the field of transition metals in biology we are concerned with a variety of homo- and hetero-polynuclear metal clusters which exhibit spin coupling. A further example for spin coupling in this field is provided by mononuclear transition metal complexes, with the paramagnetic metal site and an additional nonmetallic site forming a spin-coupled system. For both types of spin-coupled systems we present examples here, and we discuss the influence of localized and delocalized mixed-valence states, and the strength of superexchange, spin-dipolar and double-exchange contributions to spin coupling.

ChemInform Abstract: Mononuclear Transition Metal Complexes. Part 2. Complexes with Weakly Bonded Anions

ChemInformVolume 21, Issue 52 Reviews ChemInform Abstract: Mononuclear Transition Metal Complexes. Part 2. Complexes with Weakly Bonded Anions W. BECK, W. BECK Inst. Anorg. Chem., Univ. Muenchen, W-8000 MuenchenSearch for more papers by this author W. BECK, W. BECK Inst. Anorg. Chem., Univ. Muenchen, W-8000 MuenchenSearch for more papers by this author First published: December 25, 1990 https://doi.org/10.1002/chin.199052372Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue52December 25, 1990 RelatedInformation

ChemInform Abstract: New Types of Organic Synthesis by Using Metal Clusters and Mixed Metal Complexes

In homogeneous reactions catalyzed by transition metal complexes, the active species are in general mononuclear transition metal complexes and their catalytic activities are controlled by an appropriate choice of metals and ligands, especially phosphine ligands. Recently, homogeneous multimetallic catalysis has been receiving much attention because of the potential for the different metals cooperating during chemical transformations. It is expected that this cooperativity aids in the design of new, more active and selective catalysts and new types of reactions which are inaccessible through monometallic systems. Reviewed here are activation of substrates on metal clusters and various types of reactions catalyzed by metal clusters and mixed metal complexes.

金属クラスターおよび混合金属錯体を用いた新しい有機合成反応

In homogeneous reactions catalyzed by transition metal complexes, the active species are in general mononuclear transition metal complexes and their catalytic activities are controlled by an appropriate choice of metals and ligands, especially phosphine ligands. Recently, homogeneous multimetallic catalysis has been receiving much attention because of the potential for the different metals cooperating during chemical transformations. It is expected that this cooperativity aids in the design of new, more active and selective catalysts and new types of reactions which are inaccessible through monometallic systems. Reviewed here are activation of substrates on metal clusters and various types of reactions catalyzed by metal clusters and mixed metal complexes.

Acyclic and macrocyclic schiff base complexes of lanthanides and actinides

Acyclic and macrocyclic schiff base complexes of lanthanides and actinides

Mononuclear Transition Metal Complexes with CS2‐Analogous Coordination of a Thioketene

Mononuclear Transition Metal Complexes with CS₂‐Analogous Coordination of a Thioketene

A strong metal-support interaction between mononuclear and polynuclear transition metal complexes and oxide supports which dramatically affects catalytic activity

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA strong metal-support interaction between mononuclear and polynuclear transition metal complexes and oxide supports which dramatically affects catalytic activityDennis A. Hucul and Alan BrennerCite this: J. Phys. Chem. 1981, 85, 5, 496–498Publication Date (Print):March 1, 1981Publication History Published online1 May 2002Published inissue 1 March 1981https://doi.org/10.1021/j150605a009RIGHTS & PERMISSIONSArticle Views178Altmetric-Citations58LEARN 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 InReddit PDF (454 KB) Get e-Alerts

Selective reactions of transition metals and their complexes

Mechanistic features of selective catalytic hydrogenation reactions of alkynes and of aromatic hydrocarbons are discussed. Catalysts considered include molecular mononuclear transition metal complexes, dinuclear complexes, clusters, and also metal surfaces. Particular attention is given to competitive reaction systems based on alkyne-alkene and on arene-alkene reaction mixtures.

ChemInform Abstract: COMPARTMENTAL LIGANDS. PART 2. MONONUCLEAR TRANSITION‐METAL COMPLEXES OF ACYCLIC SCHIFF BASES DERIVED FROM 1,3,5‐TRIKETONES

Chemischer InformationsdienstVolume 9, Issue 7 Organoelement Compounds ChemInform Abstract: COMPARTMENTAL LIGANDS. PART 2. MONONUCLEAR TRANSITION-METAL COMPLEXES OF ACYCLIC SCHIFF BASES DERIVED FROM 1,3,5-TRIKETONES D. E. FENTON, D. E. FENTONSearch for more papers by this authorS. E. GAYDA, S. E. GAYDASearch for more papers by this author D. E. FENTON, D. E. FENTONSearch for more papers by this authorS. E. GAYDA, S. E. GAYDASearch for more papers by this author First published: February 14, 1978 https://doi.org/10.1002/chin.197807286AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume9, Issue7February 14, 1978 RelatedInformation

Compartmental ligands. Part 2. Mononuclear transition-metal complexes of acyclic Schiff bases derived from 1,3,5-triketones

A series of acyclic Schiff bases (1) derived from 1,3,5-triketones and α,ω-alkanediamines has been prepared, and their mononuclear complexes with CuII, NiII, UO2, and VO are described. Phenyl-substituted alicyclic bases are prepared by the reaction of 1-p-X-phenylhexane-1,3,5-trione (X = H, Br, Me, or OMe)(2 mol) and ethane-1,2-diamine (en)(1 mol) in ethanol; the condensation of 7,7-dimethyloctane-2,4,6-trione with en similarly yields 2,2,7,12,17,17-hexamethyl-8,11-diazaoctadeca-6,12-diene-3,5,14,16-tetraone (1 I). 6, 11-Dimethyl-7,10-diazahexadeca-5,11-diene-2,4,13,15-tetraone, (1 a), is prepared by acid hydrolysis of the macrocyclrc Schiff base 5,9,14,18-tetramethyl-1,4,10,13-tetra-azacyclo-octadeca-5,8,14,17-tetraene-7,16-dione (2a). Treatment of the alicyclic bases with metal acetates gives the corresponding mononuclear complexes. The ligands (1) are potentially tetra-anionic and have two available dissimilar compartments for complex formation, one comprising N2O2 and the other O2O2 donor sites. The co-ordination selectivity of (1) is established as a necessary prerequisite for the formation of pure heterobinuclear chelates of these ligands. The reaction of Cu[O2CMe]2 with (1a) gives three products: the two N2O2 and O2O2 positional isomers, (5a) and (6a)·H2O, and a homobinuclear complex. The mononuclear complexes of Ni, UO2, and VO show N2O2, O2O2, and O2O2 site occupancy respectively. The preference of Ni for the N2O2 site is reinforced in its reaction wth the phenyl-subsmuted bases, but here Cu shows a preference for O2O2 as do VO and UO2. The site selectivity of Ni is further exemplified in the reaction of (5a; M = Cu) with Ni[O2CMe]2 in which the Ni replaces the Cu in the ligand. The complexes have been characterised by chemical analysis and spectral measurements, and the potential role of magnetic studies in establishing the site occupancy has been investigated.