Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Transition Metal Groups

The original lettering of the transition metal groups, for example VIB, VIIB and so on is still used, but is sometimes misleading and clearly incomplete. However, we may usefully refer, for example, to... [Pg.12]

Unlike typical element groups the transition metal groups do not have head elements. [Pg.14]

Metals (mam group) Metals (transition) Metals (inner transition) Metalloids... [Pg.1328]

In another process for the synthesis of PPS, as well as other poly(arylene sulfide)s and poly(arylene oxide)s, a pentamethylcyclopentadienylmthenium(I) TT-complex is used to activate -dichlorobenzene toward displacement by a variety of nucleophilic comonomers (92). Important facets of this approach, which allow the polymerization to proceed under mild conditions, are the tremendous activation afforded by the TT-coordinated transition-metal group and the improved solubiUty of the resultant organometaUic derivative of PPS. Decomplexation of the organometaUic derivative polymers may, however, be compHcated by precipitation of the polymer after partial decomplexation. [Pg.445]

Compounds with Sc, Y, lanthanoids and actinoids are of three types. Those with composition ME have the (6-coordinated) NaCl structure, whereas M3E4 (and sometimes M4E3) adopt the body-centred thorium phosphide structure (Th3P4) with 8-coordinated M, and ME2 are like ThAsi in which each Th has 9 As neighbours. Most of these compounds are metallic and those of uranium are magnetically ordered. Full details of the structures and properties of the several hundred other transition metal-Group 15 element compounds fall outside the scope of this treatment, but three particularly important structure types should be mentioned because of their widespread occurrence and relation to other structure types, namely C0AS3,... [Pg.555]

As in the preceding transition-metal groups, the refractory behaviour and the relative stabilities of the different oxidation states can be explained by the role of the (n — l)d electrons. Compared to vanadium, chromium has a lower mp, bp and enthalpy of atomization which implies that the 3d electrons are now just beginning to enter the inert electron core of the atom, and so are less readily delocalized by the formation of metal bonds. This is reflected too in the fact that the most stable oxidation state has dropped to +3, while chromium(VI) is strongly oxidizing ... [Pg.1005]

Different main-group-, transition- and lanthanide-metal complexes can catalyze the cycloaddition reaction of activated aldehydes with activated and non-activated dienes. The chiral metal complexes which can catalyze these reactions include complexes which enable substrates to coordinate in a mono- or bidentate fashion. [Pg.164]

Classify the elements in Question 17 as metals (main group, transition, or post-transition), nonmetals, or metalloids. [Pg.45]

The acidity of benzylic protons of aromatics complexed to transition-metal groups was first disclosed by Trakanosky and Card with (indane)Cr(CO)3 [61]. Other cases are known with Cr(CO)3 [62], Mn(CO)3 [63], FeCp+ [64, 65], and Fe(arene)2+ [31, 66] but none reported the isolation of deprotonated methyl-substituted complexes. We found that deprotonation of the toluene complex gives an unstable red complex which could be characterized by 13C NMR ( Ch2 = 4.86 ppm vs TMS in CD5CD3) and alkylated by CH3I [58] Eq. (13) ... [Pg.63]

There are three types of electron transfers, firstly the generation of an electron electrochemically, by y-irradiation, or by photolytic dissociation, secondly the transfer of an electron from an inorganic or organic compound, referred to as a nucleophilic homolytic leaving group (Zollinger, 1973 a), and thirdly a transfer from a transition metal or transition metal ion complex. In this section we will discuss the fundamental aspects of these three types. In the following sections and in Chapter 10, specific examples and synthetic applications will be summarized. [Pg.190]

All d-block elements are metals (Fig. 1.63). Their properties are transitional between the s- and the p-block elements, which (with the exception of the members of Group 12) accounts for their alternative name, the transition metals. Because transition metals in the same period differ mainly in the number of /-electrons, and these electrons are in inner shells, their properties are very similar. [Pg.172]

Metallo-organics are compounds in which the atom of an element is bound to one or more carbon atoms of an organic hydrocarbon group. Many of the elements used in MOCVD are the metals of groups Ila, Ilb, Illb, IVb, Vb, and VIb, which are non-transitional. The metallo-organics thus complement the halides and carbonyls, which are the precursors for the deposition of transition metals (Groups IVa, Va, and Via) and their compounds. [Pg.85]

Table 8. Selected bond lengths (pm) and angles (°) of tetraorgaonodipnictines and their main group metal and transition metal complexes... Table 8. Selected bond lengths (pm) and angles (°) of tetraorgaonodipnictines and their main group metal and transition metal complexes...
Main group metal alkyls Transition metal salts... [Pg.35]

Phosphinidenes [1] are low-valent organophosphorus compounds that have attracted attention since the early 1980s when they were first discovered [2]. They are known in two classifications, one being the six-electron singly substituted phosphorus species (A) and the other in which the phosphorus atom carries an additional ri -stabifizing group, typically, but not necessarily, a transition metal group (B). Much has been learned about the reactivities of the complexed phos-... [Pg.95]

Phosphinidenes differ from carbenes because of the additional lone pair. This lone pair enables interactions with, e.g., a transition metal group for increased stability, while maintaining carbene-hke behavior. These terminal /] -complexed phosphinidenes differ from the p2-> fi3-> and p4-complexes, which are not part of this survey. Phosphinidenes that are stabilized by a transition metal group also relate to carbene complexes. A distinction in Fischer and Schrock-type complexes has been advanced to distinguish phosphinidene complexes with nucleophilic properties from those that are electrophiHc [ 13 ]. In this survey we address this topic in more detail. [Pg.96]

Adding a transition metal group to the phosphinidene in a q -fashion gives singlet species that are more palatable for use in chemical syntheses. Theoretical studies substantiated their preferred singlet nature, the extent of which depends on the substituent on phosphorus. When the transition metal group is M(CO)n... [Pg.100]

The last decade has seen the development of a rich and varied chemistry for or-ganometallic porphyrin complexes of the early transition metals (groups 3 and 4). However, there have been many fewer developments in the organometallic chemistry of the middle transition elements. Despite the paucity of its organometallic porphyrin compounds, molybdenum has played a very important role in... [Pg.240]


See other pages where Transition Metal Groups is mentioned: [Pg.256]    [Pg.2391]    [Pg.425]    [Pg.534]    [Pg.47]    [Pg.823]    [Pg.113]    [Pg.49]    [Pg.193]    [Pg.765]    [Pg.826]    [Pg.77]    [Pg.291]    [Pg.19]    [Pg.540]    [Pg.541]    [Pg.542]    [Pg.543]    [Pg.544]    [Pg.545]    [Pg.95]    [Pg.101]    [Pg.109]    [Pg.223]    [Pg.224]    [Pg.231]    [Pg.310]   
See also in sourсe #XX -- [ Pg.4 , Pg.12 , Pg.148 ]




SEARCH



Bimetallic Organogermanium Derivatives of Groups I, IV and VI Transition Metals

Compounds with Bonds Between Transition and Main Group Metals

Group 14 amides with transition metal complexe

Group 14 compounds transition metal complexes

Group 2-transitional metal complexes

Group 3 elements transition metal derivatives

Group IIIA Transition Metals

Group VA Transition Metals

Group VIII transition metals

Group VIII transition metals, carbon

Group theoretical predictions, transition metal

Group-IIIB-transition metal bonds

Group-IIIB-transition metal bonds reactions with

Group-Transition Metal Mixed Clusters

Groups of transition metals

Insertion into main group and post-transition metal amides

Isolobal main-group and transition-metal fragments

Main Group Element-Transition Metal Mixed Compounds

Main group element oxides reactions with transition metal complexes

Main group-transition metal cluster

Main group-transition metal cluster Zintl ions

Main group-transition metal cluster alkylation

Main group-transition metal cluster characterization

Main group-transition metal cluster coordination geometry

Main group-transition metal cluster element compounds

Main group-transition metal cluster open compounds

Main group-transition metal cluster stability

Main group-transition metal cluster substitution reactions

Main group-transition metal mixed clusters

Mixed-ligand complexes, transition metal group

Organic ligand transfer from transition metals to main group element

Protecting Groups Cleaved by Transition Metal Catalysis

Reactivity studies, transition metal group 12

Silanol complexes with group 9 transition metals

Silyl complexes with group 3 transition metals

Silylene complexes with group 6 transition metals

Sulfur bond cleavages, transition metal group 12

Terminal alkynes with Group 9 transition metals

The Nature of Transition Metal Compounds Groups 4 to

Toxicity studies, transition metal group 12

Toxicity studies, transition metal group 4 metals

Transition Group

Transition Metal Complexes with Group

Transition Metal Complexes with Group IVB Elements

Transition Metal Complexes with Group J. F. Young

Transition Metals as Protecting, Activating, and Directing Groups

Transition metal catalysts atom/group-transfer reactions

Transition metal compounds, group

Transition metal group 0 element bond

Transition metal oxides iron group oxide

Transition metal surface group orbitals

Transition metal-Group 13 element complexes

Transition metal-Group 13 element complexes characteristics

Transition metal-Group 13 element complexes ionic compounds

Transition metal-group 14 bonds

Transition metal/group 14 complexes

Transition metals, anion-binding group

Transition metals, dithiocarbamate complexes group

Transition-metal organic compounds, alkyl groups

Water exchange on main group and d-transition metal ions

© 2024 chempedia.info