Multiply trimethylstannyl substituted ferrocenes synthesis, NMR studies, X-ray structural analysis and electrochemistry

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

“…This chemical shift value is about 240 ppm to higher frequency with respect to starting compound 3a or chloride 1a, as similarly found for tributylstannylium [37]. Such an increase is most probably caused by the ionic character of [L CN (n-Bu) 2 Sn] + [Ti 2 Cl 9 ] À in benzene solution. The structure of the organotin fragment is thus composed of three carbon atoms and one intramolecularly coordinated nitrogen atom.…”

“…In the reaction mixture, CpTiCl 3 , [L CN (n-Bu) 2 Sn] + [Ti 2 Cl 9 ] À and a minor amount of (nBu) 2 SnCl 2 were detected in various NMR spectra. The 1 H NMR spectrum of [L CN (n-Bu) 2 Sn] + [Ti 2 Cl 9 ] À gave a single set of broad signals, while the 119 Sn NMR signal at 185.6 ppm indicated a four-coordinate tin atom. This chemical shift value is about 240 ppm to higher frequency with respect to starting compound 3a or chloride 1a, as similarly found for tributylstannylium [37].…”

“…The ionization of triorganotin compounds was observed in the case of tributyltin dodecamethyl-1-carba-closo-dodecaborate [37], tris(triisopropylphenyl)stannylium tetrakis(pentafluorophenyl)borate [38] both for three-coordinated tin atom and N,C,N-or O,C,O-chelating ligands derivatives for five-coordinated tin atoms [39]. The determined crystal structure of [L CN (n-Bu) 2 Sn] + [Ti 2 Cl 9 ] À revealed the same geometry for the tin atom as proposed from the solution NMR studies. Three carbon atoms are localized in the basement of the square pyramid which is capped by the nitrogen donor atom (Fig.…”

“…The chemistry of organotin(IV) compounds where the tin atom is r-bonded to a cyclopentadienyl moiety is also well established including, for example, studies of mixed valence tin(II) and tin(IV) compounds or stability and properties of tin(III) radicals generated by irradiation of Bu 4Àn Cp n Sn. Recent studies targeted mainly onto the synthesis of tin substituted ferrocenes [2] or ferrocenophanes [3], and the use of these compounds as cyclopentadienyl group transfer agents to the transition metal center [4].…”

Carbanion generation through tin-lithium exchange of vinyl-, aryl-, and hetarylstannanes

“…Though not initially aromatic, the cyclopentadienylstannanes shown in Scheme 19 lead to arylstannanes by tin-lithium exchange. 65 In both cases, tin-lithium exchange occurs preferentially at the allylic carbon to give the aromatic cyclopentadienyl anions, which then react with ferrous chloride to give the corresponding products. These compounds were later used in the synthesis of stannyl-substituted ferrocenes.…”