Derivatives of Transition Metals

As indicated by the title, these processes are largely due to the work of Ziegler and coworkers. The type of polymerisation involved is sometimes referred to as co-ordination polymerisation since the mechanism involves a catalyst-monomer co-ordination complex or some other directing force that controls the way in which the monomer approaches the growing chain. The co-ordination catalysts are generally formed by the interaction of the alkyls of Groups I-III metals with halides and other derivatives of transition metals in Groups IV-VIII of the Periodic Table. In a typical process the catalyst is prepared from titanium tetrachloride and aluminium triethyl or some related material. 

Stabilization of /j -alkyl and -aryl derivatives of transition metals can be enhanced by the judicious inclusion of various other stabilizing ligands in the complex, even though such ligands are known not to be an essential prerequisite. Particularly efficacious are potential IT acceptors (see below) such as AsPh3, PPh3,... 

Whereas Cu and Ag form complexes with derivatives of transition-metal carbonyls in which the Cu or Ag are 4 coordinated in both the reactant and in the final product, many analogous Au complexes exhibit only 2 coordination. For example, the simple Au complex Ph3PAuCI reacts with transition-metal carbonyl anions in THF to give complexes with transition-metal to Au bonds, e.g. ... 

Alkali Metal Derivatives of Metal Carbonyls, 2, 1S7 Alkyl and Aryl Derivatives of Transition Metals, 7, 1S7 Alkyl cobalt and Acylcobalt Tetracarbonyls, 4, 243 Allyl Metal Complexes, 2, 32S... 

In summary, the Lewis-like model seems to predict the composition, qualitative molecular shape, and general forms of hybrids and bond functions accurately for a wide variety of main-group derivatives of transition metals. The sd-hybridization and duodectet-rule concepts for d-block elements therefore appear to offer an extended zeroth-order Lewis-like model of covalent bonding that spans main-group and transition-metal chemistry in a satisfactorily unified manner. 

In spite of the attention focused on these bulky aryl substituents, especially in main-group chemistry, aryl ligands in which crowding is caused by the presence of ortho-aryl substituents formerly received little attention. In contrast, related terphenyl-substituted phenolate derivatives (e.g., -OC6H3-2,6-Ph2) of the early transition metals have been studied for many years, and zinc terphenolate derivatives have attracted attention (vide infra). A small number of similar aryl thiolate derivatives of transition metals (e.g., Mo, Fe, and Rh) have been characterized and published (vide infra). In addition, the related ligand -C6H2-2,4,6-Ph3 (Triph) had been employed as a ring substituent in bulky porphyrins.24... 

In this section, we will discuss organometallic derivatives of zinc, cadmium, mercury, and indium. The group IIB and IIIB metals have the d10 electronic configuration in the 2+ and 3+ oxidation states, respectively. Because of the filled d level, the 2+ or 3+ oxidation states are quite stable, and reactions of the organometallics usually do not involve changes in oxidation level. This property makes the reactivity patterns of these organometallics more similar to those of derivatives of the group IA and IIA metals than to those of derivatives of transition metals with vacancies in the d levels. The IIB metals, however, are... 

There are numerous cases of organometallic structure proof based on proton spectra. An interesting class within this group are the ir-allyl metallics (52, 57, 69, 128). Allyl derivatives of transition metal carbonyls have been made, but these are for the most part rather unstable and readily lose carbon monoxide to form a new structure, e.g.,... 

Chernyshev, E. A., Reshetova, M. D., and Volynskikh, A. D., Kremnii, gher-manii- i olovoorganicheskie proizvodnye perekhodnykh metalov [Organosilicon, -germanium and -tin Derivatives of Transition Metals ]. Niitekhim, Moskwa, 1974. 

This indirect, two-step procedure for the synthesis of trifluoromethyl derivatives of transition metals was developed after it had become evident that the reaction of CF3I with metallate ions such as Mn(CO)5 resulted in the formation of the iodide rather than the expected trifluoromethyl derivative, as indicated in Eq. (3) (16). 

I. Mass Spectra of Fluorocarbon Derivatives of Transition Metals. 113... 

At the beginning of the 1960s it was found that some simple derivatives of transition metals such as RhCl3 -3H20 and Rh(N03)3 -2H20 polymerised butadiene to trans- 1,4-polymers in protic solvents such as water and ethanol [27,28], Also, other catalysts consisting of transition metal salts (monometallic or... 

Table 5.4 [33,36,37,116,120-134] and Table 5.5 [7,74,81,103,120,122,126,135-147] report the microstructure of 1,3-butadiene polymers derived from polymerisation with some representative catalysts of the re-allylic type (if1-allyl, / 3-crotyl, /3-methallyl and higher 3-hydrocarbyl derivatives of transition metals). 

Table 5.5 Polymerisation of 1,3-butadiene with catalysts based on 71-allyl derivatives of transition metals...

Higher 43-hydrocarbyl derivatives of transition metals can be obtained by partial protolysis of the bis(7i-allyl)metal compounds formed from cyclo-octa-1,5-diene metal complexes and 1,3-butadiene with one equivalent of the Bronsted acid in the presence of the proper ligand in a polar solvent at lowered temperature (e.g. — 40°C). For instance, Ni [43-(CxHn)l and Ni—[43-(Ci2Hig)] derivatives have been yielded by the reaction of Ni(CxH 2)2 [(Ni(Cod)2] with 1,3-butadiene (C4H6), followed by treatment with a Bronsted acid, according to scheme (1) [132] and scheme (2) [37] respectively ... 

Catalysts based on 7r-allylic derivatives of transition metals supported on alumina, silica or silica-alumina gels exhibit generally enhanced activity by comparison with their unsupported counterparts, while the stereospecificity depends on the nature of the catalyst carrier. For instance, Cr(All)3, which predominantly produces 1,2-polybutadiene [137], becomes a stereospecific catalyst for the formation of trans- 1,4-polybutadiene when supported on silica or silica-alumina gel and for the formation of cis- 1,4-polybutadiene when supported on alumina [148]. However, an increase in the content of cis-1,4 monomeric units in polybutadiene with increasing silica concentration in n-allylnickel-alumina-silica catalysts has been observed [149]. 

The reactions of silyl hydrides with low-valent metal complexes is a common method of preparing silyl derivatives of transition metals (14-16). However, relatively little work has been directed to the study of H/H (H/D) exchange. From the studies of Sommer et al. (17), it has been established that chloroplatinic acid, (QH4 P CU, Co2(CO)8, L Ir(CO)Cl,... 

The Chemical Shifts of Carbene Derivatives OF Transition Metals... 

A102. F. Dawans, J. P. Duran, and P. Teyssi6, Stereospecific Polymerization by Derivatives of Transition Metals. CNRS, Paris, 1969. 

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