Cyclopentadienyl substitution

The complex (197) with a dithiocarboxylate ligand coordinated to platinum(II) bonded through both monodentate carbon and die chelating dithiocarboxylate ligand has been prepared from either the thiocarbonyl platinum(II) precursor or the carbon disulfide adduct of platinum(O).1796,1797 A cyclopentadienyl-substituted dithiocarboxylate ligand (198) can be used to prepared S,S-bonded platinum(II) and (IV) complexes Pt(C5H4CS2)2 and PtfCsKtCS 2-. The complexes show v(PtS) at 340 cm-1, and in each case electronic absorption bands of the Pt— L type are at 19 500 cm-1 and 29 500 cm-1.1798... 

Cyclopentadienylstannanes, preparation, 3, 840 z/ .tz/-(Cyclopcritadienyl-substituted-indenyl)zirconocene dichlorides, preparation, 4, 958 Cyclopentadienyl-substituted phosphaferrocenes, preparation, 6, 210-211... 

The analogous strategy for synthesizing metal-metal bond-containing polymers also uses difunctional, cyclopentadienyl-substituted metal dimers. A sample step-growth polymerization reaction is shown in equation 3, which... 

The same type of precatalysts catalyze the regiospecific hydroamination/ cyclization of aliphatic and aromatic aminoalkynes RC=(CH2) NH2 [295]. The mechanistic scenario parallels that of the corresponding aminoolefin cyclization. However, the cyclization of the aminoalkynes is 10-100 times more rapid, and a rather contrary effect of the cyclopentadienyl substitution on N, was observed. 

Cyclopentadienyltin cations, the representatives of a third class of n-cyclopentadienyltin compounds, were first observed in the mass spectra of cyclopentadienyl-substituted organotin(II) and organotin(IV) species. The first such species to be isolated was the Me5C5Sn+ cation, in the form of the tetrafluoroborate salt (LXXa) (Scheme 6) (192,231). Subsequently, other electrophiles have been employed leading to the compounds LXXb-d (Scheme 6) (202,250). 

Among catalysts based on cyclopentadienyl-substituted half-sandwich titanocenes, the IndTiCb—[Al(Me)0]x catalyst in particular has extremely high activity and stereospecificity. It is relatively more sensitive to polymerisation conditions. A minimum concentration of about 50 mmol of methylaluminoxane was required to obtain the desired polymerisation activity. The activity also increases as the [Al(Me)0]x concentration increases, reaching a maximum at an Al/Ti molar ratio of 4000. For instance, the productivity of the IndTiCU—[Al(Me)0]x catalyst under optimum polymerisation conditions... 

C5Me5)Ln[(/i.-OCH2f-Bu)(/i.-Me)AlMe2]2 (Ln = Y, Lu) [142] were obtained from the reactions of cyclopentadienyl-substituted derivatives. According to Scheme 27, the addition of stoichiometric amounts of trimethylaluminum (n(Ln) n(Al) = 1 2) to the dimeric half-lanthanidocene bis(alkoxide) complexes quantitatively gave bis(TMA) adducts. 

Extending the theme of cyclopentadienyl-substituted methanides, complexes 51, 54, and 56 were used to prepare the mono-pentamethyl-cyclo-pentadienyl complexes 62, 63, and 64 in which the metal-methanide bond was maintained.39 Complexes 62-64 were tested for their activity in the polymerisation of e-caprolactone and they exhibited low activities. However, treatment of 62-64 with one equivalent of iso-propyl alcohol resulted... 

Gas-phase photoelectron spectroscopy has been used to study the bonding in CpM(CO)4, Cp M(CO)4, and (rj -C5H4COMe)Nb(CO)4. The character of two overlapping ionizations in the lowest ionization energy region is dominated by the carbonyls rather than by the metals. The second group of ionizations corresponds to orbitals with predominantly cyclopentadienyl n character that donate to empty metal d orbitals. A much larger shift of these ionizations is observed upon cyclopentadienyl substitution. ... 

Ring-bridged vanadocene halide and dihalide, (28) and (29) are obtained from bis(cyclopentadienyl)-substituted dianion (27) as shown in Scheme 16. Furthermore,... 

Cyclopentadienyl-substituted vanadium(III) compound (93) is also allowed to undergo the substitution reaction to give the a-alkyl, a-alkynyl, or a-aryl complexes (94, Scheme 52). 2,132-137 [nbu4][V(C6C15)4], which is prepared... 

Treatment of ( -C5H5)2Ni or t/ -CjHjNia, formed in situ, with allylmagnesium chloride affords the cyclopentadienyl-substituted complex ... 

The generation of the precursors for cyclopentadienyl-silanol-functionalized iron complexes involves the formation of the corresponding iron anion in a first step [6]. 2a is obtained by reductive cleavage of the methoxysilyl-cyclopentadienyl-substituted iron dimer 1 with sodium amalgam in THF (Scheme 1). This reaction is restricted to alkoxysilyl-cyclopentadienyl-fiinctionalized iron anions because of the limited access to the corresponding Si-H-functionalized iron dimers. 

The pyrolysis of 1,1-disubstituted silacyclobutanes has been used as a method for the preparation of 1,1,3,3-tetrasubstituted 1,3-disilacyclobutanes183. Copyrolysis of two different 1,1-disubstituted silacyclobutanes yielded mixtures containing 1,3-disilacyclobutanes arising from all possible combinations of the two silenes present (equation 51). The preparative method failed in the case of cyclopentadienyl-substituted silacyclobutanes183, 184, presumably due to competing intramolecular reactions of the silene. The thermolysis of trimethylsilylcyclopentadiene may also proceed via a silene184. 

The stability of ruthenium analogues of the Lapinte compound depends on the cyclopentadienyl substitution. Cyclic voltammetric studies of neutral CpRu(II) precursors by the Tilset group show near-reversibility but the oxidation pro-... 

For clarity, the following abbreviations are used throughout the text and schemes [Ln] = bis(cyclopentadienyl, substituted or not, or related ligands)lanthanide... 

Hydrocarbon anions such as fluorenyl, indenyl, and cyclopentadienyl substitute for fluoride, leading, for example, to (phenylindene)Cr(CO)3 complex (20) [36,37]. 

Cyclopentadienyl-Substituted Silanetriols and Novel Titanasiloxanes 431 Synthesis of these compounds was accomplished by controlled hydrolysis as depicted in Eq. 1. 

While useful precursors for the deposition of tungsten and molybdenum are commercially available [i.e. W(CO)e and Mo(CO)6], the standard precursor for silicon (SiDi) has some disadvantages (toxic, pyrophoric). Cyclopentadienyl-substituted silanes have proven to be an easy-to-handle alternative [3]. In this work (CsMe5)Si2H5 and (C5Me4H)SiH3 are used to prepare multilayers and to compare the abilities of both precursors under hot-filament CVD conditions. 

Hot-filament MOCVD was successfiilly introduced as a new method for the deposition of thin silicon films, using cyclopentadienyl-substituted silanes as precursors. Due to its low fragmentation temperature and the high silicon growth rate (CsMe5)Si2H5 has proven to be a useful material for silicon thin film deposition. The use of a hot filament does not affect the impurities in the film, but leads, due to the lowered substrate temperatures, to a clearly improved interface quality of the silicon-tungsten multilayers. 

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