Cationic Arylpalladium Complexes with Chelating Diamine Ligands, [PdAr(N−N)(solv)]BF₄ (N−N = N,N,N‘,N‘-tetramethylethylenediamine, 2,2‘-bipyridine, 4,4‘-dimethyl-2,2‘-bipyridine). Preparation, Intermolecular Coupling of the Aryl Ligands, and Insertion of Alkyne and Allene into the Pd−C Bond

Abstract

Iodo(aryl)palladium complexes, [PdI{C 6 H 3 (CF 3 ) 2 -3,5}(N-N)] (N-N ) tmeda, bpy, 4,4′dimethyl-2,2′-bipyridine (Me 2 bpy)), react with AgBF 4 in CH 3 CN, acetone, and THF to yield stable cationic arylpalladium complexes [Pd{C 6 H 3 (CF 3 ) 2 -3,5}(N-N)(solv)]BF 4 . A similar reaction of AgBF 4 with [PdI(C 6 H 3 Me 2 -3,5)(bpy)] in CH 3 CN gives [Pd(C 6 H 3 Me 2 -3,5)(bpy)-(CH 3 CN)]BF 4 . The complex does not change its NMR spectrum for 1 h at room temperature in CD 3 CN but undergoes decomposition upon dissolution in acetone to release 3,3′,5,5′tetramethylbiphenyl. Addition of AgBF 4 to acetone or THF solutions of [PdI(Ar)(bpy)] (Ar ) Ph, C 6 H 3 Me 2 -3,5) and of [PdI(Ar)(Me 2 bpy)] (Ar ) C 6 H 4 OMe-4, C 6 H 3 Me 2 -3,5) does not lead to isolation of the cationic arylpalladium complexes and causes intermolecular coupling of the aryl ligands to yield the corresponding biaryls. The reaction of AgBF 4 with [PdI(C 6 H 3 Me 2 -3,5)(bpy)] in the presence of an excess amount of dimethyl acetylenedicarboxylate (DMAD) in CH 3 CN gives [Pd(CZdCZ-CZdCZ-C 6 H 3 Me 2 -3,5)(bpy)(CH 3 CN)]BF 4 (Z ) COOMe) via insertion of two acetylene molecules into the Pd-aryl bond. A similar reaction in acetone or THF causes insertion of three DMAD molecules into the Pd-aryl bond and cyclization of the formed Pd-(CZdCZ) 3 -Ar group to give the product containing a cyclopentadiene structure in the ligand. [PdI(CZdCZ-C 6 H 3 Me 2 -3,5)(bpy)] reacts with AgBF 4 in CH 3 CN to form a cationic complex, [Pd(CZdCZ-C 6 H 3 Me 2 -3,5)(bpy)(CH 3 CN)]BF 4 . A series of cationic Pd complexes, formed through insertion of one, two, and three alkyne molecules into the Pd-aryl bond, are characterized by X-ray crystallography or NMR spectroscopy. Phenylallene reacts with [PdI(C 6 H 3 Me 2 -3,5)(bpy)] in the presence of AgBF 4 to give [Pd{η 3 -CH 2 C-(C 6 H 3 Me 2 -3,5)CHPh}(bpy)]BF 4 via insertion of the CdC double bond of the allene into the Pd-C bond of the cationic arylpalladium complex. The π-allylpalladium complex crystallizes exclusively in a form with a syn-oriented phenyl substituent but exists in solution as a mixture of the isomers with a syn or anti phenyl substituent.

Transmetalation of arylpalladium and platinum complexes. Mechanism and factors to control the reaction

“…The reaction of PtCl 2 (cod) with excess PdCl(Ph)(bpy) in CH 2 Cl 2 forms PtCl(Ph)(cod), as shown in Eq. (14). The products of the reaction do not contain PtPh 2 (cod).…”

“…The reaction of AgBF 4 with these complexes in acetone or THF produces biaryl as shown in Eq. (2), while the reaction in MeCN results in isolation of the cationic arylpalladium complex ½PdArðNCMeÞ-ðbpyÞ þ ðBF À 4 Þ [14]. The reaction forming …”

The mechanism of the Pd-catalyzed formation of coumarins: a theoretical study

“…21 The same reference concedes that Pd(II) catalysts prefers to bind in the cis form in general, 21 and it has been already shown that in most cases the cis-addition of the Pd(II) catalyst is preferred. 32,33 Thus, in order to clarify the plausibility of the EAS mechanism, the relative energies of the two forms of bound Pd(II) catalyst (the cis-addition form (panel 1 in Fig. 2) and the trans-addition form (panel 2 in Fig.2)) have been determined.…”

Bridging allyl ligands upon allene insertion into electron-deficient triosmium-hydride clusters [Os3(CO)9(μ3-NSC7H3R)(μ-H)] (R = H, Me)

“…Allene itself reacts with the lightly stabilized clusters [Os 3 (CO) 12Àx (NCMe) x ] (x ¼ 1,2) under mild conditions to afford [Os 3 (CO) 11 (m-h 1 :h 3 -CH 2 ]C]CH 2 )] [22] and [Os 3 (CO) 10 (m 3 -h 1 :h 2 :h 3 -C 6 H 8 )] [23] respectively, the latter arising from facile coupling of two molecules of allene. As far as we are aware, the only previous report of the reactivity of allene towards a hydridoosmium cluster was that by Deeming and co-workers who studied the reaction with [Os 3 (CO) 10 (m-H) 2 ] with allene [24].…”

“…In both the allyl ligand is bonded to the remote osmium that is the one which has no bonding interaction with benzothiazolide ligand through a putative peh 2 -interaction but the other end of this ligand is coordinated to benzoliazolide-nitrogen-bounded osmium in 3 and carbon-bounded osmium in 4 in a similar fashion. The central carbon atom, C(11), of this ligand is severely disordered in 4 and in the second molecule of 3. However, the osmiumecarbon bond involving the central carbon of the allyl ligand is significantly longer [Os(1)eC(11) 2.577(16) and Os(2)eC(11) 2.644(11) Å in 3; Os(1)eC(11) 2.631(11) and Os(3)eC(11) 2.650(11) Å in 3] than those involving the terminal carbons [Os(1)eC(12) 2.165(15) and Os(2)e C(10) 2.150(15) in 3; Os(1)eC(12) 2.195(11) and Os(3)eC(10) 2.219…”