“…The closest example to the Cp 2 Ti(O t Bu)-induced heterobimetalic formation is a brief comment from a research group of Moïse, in which reaction of Cp 2 TiCl with Co 2 (CO) 8 slowly produced Cp 2 TiCl (l-OC)Co 3 (CO) 9 [22]. We reexamined the reaction of Cp 2 TiCl with Co 2 (CO) 8 and compared its reaction rate with the reaction of 1a with Co 2 (CO) 8 under similar conditions; The reaction of Cp 2 TiCl was approximately 150 times slower than that of 1a.…”
“…The closest example to the Cp 2 Ti(O t Bu)-induced heterobimetalic formation is a brief comment from a research group of Moïse, in which reaction of Cp 2 TiCl with Co 2 (CO) 8 slowly produced Cp 2 TiCl (l-OC)Co 3 (CO) 9 [22]. We reexamined the reaction of Cp 2 TiCl with Co 2 (CO) 8 and compared its reaction rate with the reaction of 1a with Co 2 (CO) 8 under similar conditions; The reaction of Cp 2 TiCl was approximately 150 times slower than that of 1a.…”
“…The VCp 2 /Co 2 (CO) 8 System . An earlier study of the vanadocene/Co 2 (CO) 8 system showed that the treatment of a VCp‘ 2 solution (Cp‘ = C 5 H 5 , C 5 H 4 CMe 3 , C 5 H 4 Co 2 Me, C 5 Me 5 , C 5 Me 4 Et) with Co 2 (CO) 8 affords heterobimetallic compounds whose composition depends on the substituents on the vanadocenes. , …”
Section: Resultsmentioning
confidence: 99%
“…The reaction between VCp* 2 and Co 2 (CO) 8 affords a black solid of composition VCp* 2 Co(CO) 4 (eq 8) whose IR spectrum in solution shows absorptions at 2000 s, 1930 vs, and 1766 s cm -1 ; the low-wavenumber absorption suggests the presence of a bridging carbonyl, as already observed in Cp* 2 V(μ-OC)V(CO) 5 (1708 cm -1 ), and therefore a similar structure can be envisaged for the cobalt−vanadium compound (Figure ). The methyl-substituted derivative Cp* 2 V(μ-OC)Co(CO) 3 is more robust in solution than the nonmethylated analogue; nevertheless, it slowly decomposes, as evidenced by the formation of a solid together with the appearance in solution of the absorptions typical of Co 4 (CO) 12 . , 4 Proposed structure for Cp* 2 V(μ-OC)Co(CO) 3 containing a μ-isocarbonyl bridge.…”
Section: Resultsmentioning
confidence: 99%
“…An earlier study of the vanadocene/Co 2 (CO) 8 system showed that the treatment of a VCp′ 2 solution (Cp′ ) C 5 H 5 , C 5 H 4 CMe 3 , C 5 H 4 Co 2 -Me, C 5 Me 5 , C 5 Me 4 Et) with Co 2 (CO) 8 affords heterobimetallic compounds whose composition depends on the substituents on the vanadocenes. 10,11 In the framework of the present study, we have reexamined the VCp 2 /Co 2 (CO) 8 reaction, confirming the results of Moı ¨se and co-workers 10,11 As a matter of fact, the reaction between VCp 2 and Co 2 (CO) 8 at low temperature is fast and affords high yields of spectroscopi-cally pure Cp 2 VCo(CO) 4 , which can be isolated and safely handled in the solid state only at low temperature (ca. 0 °C).…”
Section: Resultsmentioning
confidence: 99%
“…Due to the electron count of 14, the [VCp 2 ] + cation gives adducts of general formula [VCp 2 L n ] + by reaction with Lewis bases L. For example, adducts with CO, isocyanides, 6a,b tertiary phosphines,6g nitriles, THF, and acetone 6g,9 have been obtained from bis(cyclopentadienyl)vanadium(III) halides or by direct oxidation of vanadocenes in the presence of the appropriate ligand. Moreover, some authors have reported the reaction of VCp 2 or substituted congeners with metal carbonyls, 6f,− showing that, in some cases, heterobimetallic compounds can be obtained. In the case of the reaction of VCp 2 with V(CO) 6 under a nitrogen atmosphere “a mixture of at least two different compounds was formed”, but the individual components could not be resolved 6f…”
The one-electron oxidation of vanadocene, VCp 2 , by [FeCp 2 ] + in toluene affords the 14-electron [VCp 2 ] + cation, which has been isolated as an unsolvated species for the first time. Vanadium hexacarbonyl reacts with VCp 2 to give the µ-isocarbonyl derivative Cp 2 V(µ-OC)V-(CO) 5 as a transient species, which has been characterized in solution by IR analysis. By reaction of VCp 2 with V( 13 CO) 6 followed by treatment with 12 CO, the ionic dicarbonyl derivative [VCp 2 ( 12 CO) 2 ][V( 13 CO) 6 ] is formed, thus showing that during the formation of the ionic compound no redistribution of the carbonyl ligands between the two metal centers occurs. Bis(cyclopentadienyl)vanadium(II) and Co 2 (CO) 8 give Cp 2 VCo(CO) 4 , which slowly decomposes in solution even at low temperature to give [VCp 2 (CO) 2 ][Co(CO) 4 ], which was identified by conventional methods, including single-crystal X-ray diffraction. The reactivity of the unsolvated [VCp 2 ] + cation as well as that of the heterobimetallic compound containing vanadium and cobalt with several Lewis bases is reported.
The synthesis of enantiomerically pure titanocenes is limited to cases with enantiomerically pure substituents at the cyclopentadienyl ligands and to ansa-titanocenes. For the latter complexes, the use of achiral ligands requires a resolution of enantiomers and frequently also a separation of the diastereoisomers obtained after metalation. Here, we introduce a new synthetic method that relies on the use of enantiomerically pure camphorsulfonate (CSA) ligands as control elements for the absolute and relative configuration of titanocene complexes. Starting from the conformationally flexible (RC 5 H 4 ) 2 TiCl 2 , the desired conformationally locked and hence enantio-and diastereomerically pure complexes (RC 5 H 4 ) 2 Ti(CSA) 2 are obtained in just two steps. According to X-ray crystallography the (RC 5 H 4 ) 2 Ti fragment is essentially C 2 -symmetric and nuclear magnetic resonance displays overall C 2 -symmetry. We applied density functional theory methods to unravel the dynamics of the complexes and the mechanisms and selectivities of their formation.
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