“…In a related germyl system studied by Satge ´et al, photolytic dissociation of a proposed germylene intermediate was also observed and quantitative trapping could be achieved by quinone or dimethyl disulfide. 4 Similar chemistry appears to be operative in the transition metal catalyzed rearrange-ment of oligosilanes observed by Pannell et al 1b We are aware of one report of the photolytic dissociation of an isolable, stable complex containing a germylene or silylene ligand. Zybill et al have isolated base-stabilized silylene complexes of iron and chromium and found that photolysis dissociates the silylene with the concomitant formation of polysilane.…”
Group 10 metal germylene complexes of general formula (R 3 P) 2 MGeQ 2 are found to be highly photosensitive. Ambient fluoresent lighting causes complete decomposition of nickel germylene species in less than one minute in the presence of germylene traps. The formation of metallacycle (Et 3 P) 2 Pt(µ-η 2 -H 2 CO)Ge[N-(SiMe 3 ) 2 ] 2 and the photochemical cycloreversion reaction are also reported.
“…In a related germyl system studied by Satge ´et al, photolytic dissociation of a proposed germylene intermediate was also observed and quantitative trapping could be achieved by quinone or dimethyl disulfide. 4 Similar chemistry appears to be operative in the transition metal catalyzed rearrange-ment of oligosilanes observed by Pannell et al 1b We are aware of one report of the photolytic dissociation of an isolable, stable complex containing a germylene or silylene ligand. Zybill et al have isolated base-stabilized silylene complexes of iron and chromium and found that photolysis dissociates the silylene with the concomitant formation of polysilane.…”
Group 10 metal germylene complexes of general formula (R 3 P) 2 MGeQ 2 are found to be highly photosensitive. Ambient fluoresent lighting causes complete decomposition of nickel germylene species in less than one minute in the presence of germylene traps. The formation of metallacycle (Et 3 P) 2 Pt(µ-η 2 -H 2 CO)Ge[N-(SiMe 3 ) 2 ] 2 and the photochemical cycloreversion reaction are also reported.
“…Reaction of V with R 3 GeH could then release the carbocycle and regenerate the palladium germyl complex II (Scheme ) . In support of the proposed mechanism, several transition-metal germyl complexes have been isolated, ,, and the β-migratory insertion of both alkynes 25 and styrene into a Pd−Ge bond has been observed. 2 …”
Section: Resultsmentioning
confidence: 75%
“…Cyclization/hydrosilyation constitutes a subset of a larger body of catalytic cyclization/addition protocols which employ HSnBu 3 , X−CN (X = SiMe 3 , GeMe 3 ), X−SiR 3 (X = SiR 3 , SnR 3 , BR 2 ), or X−SnR 3 (X = SnR 3 , BR 2 ) as stoichiometric reductants. Although procedures for the transition-metal-catalyzed hydrogermylation of alkynes, , alkenes, and allenes 15 have been developed, cyclization/hydrogermylation has not been demonstrated. For this reason, we have investigated the potential of palladium-catalyzed cyclization/hydrogermylation and report our results herein.…”
A 1:1 mixture of the palladium phenanthroline complex (phen)Pd(Me)Cl and NaBAr4 (phen
= 1,10-phenanthroline; Ar = 3,5-C6H3(CF3)2) catalyzed the reaction of 4,4-disubstituted 1,6-dienes with trialkylgermanes at 80 °C in 1,2-dichloroethane (DCE) to form R3GeCH2-substituted cyclopentanes in good yield with high trans selectivity.
“…Numerous stable σ-bonded metal germylene complexes have been synthesized in the last few decades; 41 however, comparatively fewer studies have emphasized the reactivity of the metal-germylene bond. 5,7,19,26,27,[29][30][31][32][33]43,44 To study the potential for cooperative reactivity of the M-Ge bond, we have explored the reactivity of the stable germylene ligand Ge[N(SiMe 3 ) 2 ] 2 , first reported by Lappert, 34,35 bound to platinum. Various small organic and inorganic molecules, including O 2 , CO 2 , PhNO, and H 2 CO, will react with platinum germylenes such as (Et 3 P) 2 PtGe[N(SiMe 3 ) 2 ] 2 , without cleavage of the Pt-Ge bond, to form four-membered metallocycles.…”
The reaction of
(2) with paraformaldehyde under photolytic
conditions results in the insertion of formaldehyde into the Pd−Ge bond, with bond cleavage,
to give (Et3P)2Pd(μ-S)(μCH2O)Ge[N(SiMe3)2]2 (3). Subsequent addition of CO to 3 results in
migratory insertion into the Pd−C bond, followed by rapid reductive elimination to regenerate
the Pd0 metal center and give a unique five-membered organic heterocycle,
(6). The X-ray crystal structure of the dppe (dppe = bis(diphenylphosphino)ethane) derivative of 3, (dppe)Pd(μ-S)(μCH2O)Ge[N(SiMe3)2]2 (4), is reported.
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