Synthesis and reactivity studies of Pd(II) complexes of the bulky CH(SiMe3)2 group. X ray structure of the indenyl derivative (η-Ind)Pd[CH(SiMe3)2](PMe3)
“…In consequence, and as we have observed previously in similar indenylpalladium complexes, we conclude that the hapticity of the indenyl ligand is intermediate between η 3 and η 5 . Very recently, an indenylpalladium complex has been described and the authors have found a similar ambiguity in establishing the hapticity of this ligand 1 Thermal ellipsoid plot of the cation of complex 12 (30% probability levels) with the labeling scheme.…”
Section: Resultsmentioning
confidence: 93%
“…In this paper, we show this type of reaction to be more general as it applies to other arylpalladium complexes−with or without the three methoxy groups−and using the same or other alkynes. Therefore, this represents a new method for the synthesis of indenylpalladium complexes (some highly functionalized) of which very few examples are known. − In addition, while in most previous studies only symmetrical alkynes were used, we now present the results of using some unsymmetrical ones, which allows us to propose a new empirical scale to predict the regioselectivity of the insertion reactions. 1 …”
o-Formylaryl)palladium complexes [Pd{C 6 H(CHO)-6-R 3 -2,3,4}X(N-N)] [R ) OMe; X ) Cl; N-N ) bpy (2,2′-bipyridine) (1a), tmeda (N,N,N′,N′-tetramethylethylenediamine) (1b). R ) H; X ) Br; N-N ) bpy (2a), tmeda (2b)] react with ylides PhCHdPPh 3 , pyCHdPPh 3 (py ) 2-pyridyl), or ClCHdPPh 3 to give the (o-alkenylaryl)palladium derivatives [Pd{C 6 -The compounds 3a, 4, and 6a,b are obtained as mixtures of E and Z isomers, whereas the formation of 3b and 5 is stereoselective (E isomer). The reaction of the (o-acetylaryl)palladium complexes [Pd{C 6 HC(O)Me-6-(OMe) 3 -2,3,4}Cl(tmeda)] ( 7) and [Pd{C 6 H 4 (C(O)Me)-2}Br(bpy)] (8) with bases results in the formation of the 3-palladaindan-1-ones [Pd(κ 2 -{C 6 HC(O)CH 2 -6-(OMe) 3 -2,3,4})(tmeda)] (9) and [Pd(κ 2 -{C 6 H 4 C(O)CH 2 -2}(bpy)] (10). Complexes 3b and 6a,b react with alkynes RCtCR′ to give indenylpalladium complexes [Pd{η-C 9 HBn-1-R-2-R′-3-(OMe) 3 -5,6,7}(tmeda)]TfO [Bn ) benzyl, TfO ) CF 3 SO 3 , R ) R′ ) Me (11); R ) C(O)Me, R′ ) H (12)] and [Pd{η-C 9 H 4 Bn-1-R-2-R′-3}(N-N)]TfO [R ) R′ ) H, N-N ) bpy (13a), tmeda (13b); R ) R′ ) Me, N-N ) bpy (14a), tmeda (14b); R ) R′ ) Et, N-N ) bpy (15a), tmeda (15b); R ) R′ ) Ph, N-N ) bpy (16a), tmeda (16b); R ) Ph, R′ ) H and R ) H, R′ ) Ph, N-N ) bpy (17a); R ) H, R′ ) Ph, N-N ) tmeda (17b); R ) Ph, R′ ) Me, N-N ) bpy (18a), N-N ) tmeda (18b)]. Complex 3b reacts with Me 2 CdCdCH 2 , CS 2 , or MeNdCdS to give [Pd(η 3 -CMe 2 C{C 6 H(E-CHdCHPh)-6-(OMe) 3 -2,3,4}CH 2 )(tmeda)]Tf O (19), [Pd(S 2 C{C 6 H-(E-CHdCHPh)-6-(OMe) 3 -2,3,4})(tmeda)]TfO (20), or [Pd(SC(NMe){C 6 H(E-CHdCHPh)-6-(OMe) 3 -2,3,4})(tmeda)]TfO (21). The crystal structures of 12, 17b, and 18a have been determined; the hapticities of the indenyl five-membered rings are intermediate betwen η 3 and η 5 .
“…In consequence, and as we have observed previously in similar indenylpalladium complexes, we conclude that the hapticity of the indenyl ligand is intermediate between η 3 and η 5 . Very recently, an indenylpalladium complex has been described and the authors have found a similar ambiguity in establishing the hapticity of this ligand 1 Thermal ellipsoid plot of the cation of complex 12 (30% probability levels) with the labeling scheme.…”
Section: Resultsmentioning
confidence: 93%
“…In this paper, we show this type of reaction to be more general as it applies to other arylpalladium complexes−with or without the three methoxy groups−and using the same or other alkynes. Therefore, this represents a new method for the synthesis of indenylpalladium complexes (some highly functionalized) of which very few examples are known. − In addition, while in most previous studies only symmetrical alkynes were used, we now present the results of using some unsymmetrical ones, which allows us to propose a new empirical scale to predict the regioselectivity of the insertion reactions. 1 …”
o-Formylaryl)palladium complexes [Pd{C 6 H(CHO)-6-R 3 -2,3,4}X(N-N)] [R ) OMe; X ) Cl; N-N ) bpy (2,2′-bipyridine) (1a), tmeda (N,N,N′,N′-tetramethylethylenediamine) (1b). R ) H; X ) Br; N-N ) bpy (2a), tmeda (2b)] react with ylides PhCHdPPh 3 , pyCHdPPh 3 (py ) 2-pyridyl), or ClCHdPPh 3 to give the (o-alkenylaryl)palladium derivatives [Pd{C 6 -The compounds 3a, 4, and 6a,b are obtained as mixtures of E and Z isomers, whereas the formation of 3b and 5 is stereoselective (E isomer). The reaction of the (o-acetylaryl)palladium complexes [Pd{C 6 HC(O)Me-6-(OMe) 3 -2,3,4}Cl(tmeda)] ( 7) and [Pd{C 6 H 4 (C(O)Me)-2}Br(bpy)] (8) with bases results in the formation of the 3-palladaindan-1-ones [Pd(κ 2 -{C 6 HC(O)CH 2 -6-(OMe) 3 -2,3,4})(tmeda)] (9) and [Pd(κ 2 -{C 6 H 4 C(O)CH 2 -2}(bpy)] (10). Complexes 3b and 6a,b react with alkynes RCtCR′ to give indenylpalladium complexes [Pd{η-C 9 HBn-1-R-2-R′-3-(OMe) 3 -5,6,7}(tmeda)]TfO [Bn ) benzyl, TfO ) CF 3 SO 3 , R ) R′ ) Me (11); R ) C(O)Me, R′ ) H (12)] and [Pd{η-C 9 H 4 Bn-1-R-2-R′-3}(N-N)]TfO [R ) R′ ) H, N-N ) bpy (13a), tmeda (13b); R ) R′ ) Me, N-N ) bpy (14a), tmeda (14b); R ) R′ ) Et, N-N ) bpy (15a), tmeda (15b); R ) R′ ) Ph, N-N ) bpy (16a), tmeda (16b); R ) Ph, R′ ) H and R ) H, R′ ) Ph, N-N ) bpy (17a); R ) H, R′ ) Ph, N-N ) tmeda (17b); R ) Ph, R′ ) Me, N-N ) bpy (18a), N-N ) tmeda (18b)]. Complex 3b reacts with Me 2 CdCdCH 2 , CS 2 , or MeNdCdS to give [Pd(η 3 -CMe 2 C{C 6 H(E-CHdCHPh)-6-(OMe) 3 -2,3,4}CH 2 )(tmeda)]Tf O (19), [Pd(S 2 C{C 6 H-(E-CHdCHPh)-6-(OMe) 3 -2,3,4})(tmeda)]TfO (20), or [Pd(SC(NMe){C 6 H(E-CHdCHPh)-6-(OMe) 3 -2,3,4})(tmeda)]TfO (21). The crystal structures of 12, 17b, and 18a have been determined; the hapticities of the indenyl five-membered rings are intermediate betwen η 3 and η 5 .
“…Synthesis. The main synthetic pathway to known IndPd compounds involves the metathetic reactions of MInd (M = Li, Na) with various L n PdCl m precursors (Scheme ). − However, when we applied this methodology for the synthesis of the complexes IndPd(PR 3 )Cl from the precursors (PR 3 ) 2 PdCl 2 (R = Ph, Me), we obtained the homocoupling products 1,1‘-biindene and Pd(PR 3 ) n (Scheme ). A similar observation has been made during the syntheses of the analogous IndNi(PR 3 )Cl complexes 5a.…”
Section: Resultsmentioning
confidence: 99%
“…In contrast, t -BuNC converted 6 to the dimeric derivative {(η 1 -Ind)( t -BuNC)Pd(μ-Cl)} 2 ( 10 ; Scheme ), which could be isolated in 57% yield. Complex 10 is the first example of an isolated and fully characterized Pd II complex featuring an η 1 -Ind moiety, but Poveda and co-workers have reported the in situ generation and spectroscopic characterization of a monomeric (η 1 -Ind)Pd II complex (Scheme ) 12a. The conversion of 6 to the complexes 4 and 7 − 10 is analogous to a ligand displacement reaction and likely proceeds by the initial coordination of the incoming ligand (associative mechanism); it is interesting to note, however, that phosphine ligands displace the bridging Cl, whereas t -BuNC causes a change in the hapticity of Ind.…”
Section: Resultsmentioning
confidence: 99%
“…Our interest in the structures and catalytic activities of the IndNi complexes prompted us to explore the chemistry of analogous Pd compounds in order to elucidate the influence of the metal center on the chemistry of these compounds. Relatively little is known about the reactivities of IndPd complexes, but the preparation and characterization of the following compounds have been reported: {(η 3 -Ind)Pd(μ-Cl)} 2 , {(μ-η 3 -Ind)Pd(CNR)} 2 (R = t- Bu, 2,6-(CH 3 ) 2 C 6 H 3 , 2,4,6-(CH 3 ) 3 C 6 H 2 , 2,4,6-( t -Bu) 3 C 6 H 2 ), (η 3 -Ind)Pd(PMe 3 )(CH(SiMe 3 ) 2 ), and [(η 3 -Ind)Pd(LL)] + 13 (LL = bipy, tmeda). In addition, a preliminary communication has appeared on the preparation of a series of Ind derivates from the reaction of cyclopropene and (PhCN) 2 PdCl 2 …”
The dimer {(η3-Ind)Pd(μ-Cl)}2 (6) reacts with t-BuNC to give the dimeric species {(η1-Ind)(t-BuNC)Pd(μ-Cl)}2 (10), whereas reaction with PR3 gives the complexes (η-Ind)Pd(PR3)Cl
(R = Ph (4), Cy (7), Me (8), OMe (9)). Complexes 4 and (1-Me-Ind)Pd(PPh3)Cl (5) can also be
prepared by reacting (PhCN)2PdCl2 with LiInd and PPh3. The structural characterization
of complexes 4−7, 9, and 10 by 1H and 13C NMR spectroscopy and single-crystal X-ray
diffraction studies has allowed an analysis of the indenyl ligand's mode of coordination, both
in the solid-state and in solution. Compounds 4, 6, and 7 react with PhSiH3 in the absence
of cocatalysts, whereas reaction with ethylene requires the presence of excess MAO to give
polyethylene.
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