Synthesis and X-ray Crystallographic Characterization of (μ-(Diphenylphosphino)phenyl-C²,P)palladium Bromide. A Novel Tetranuclear Metalated Compound

Abstract

The synthesis and crystal structure of a tetranuclear palladium cluster, [Pd(PC)Br]4 (PC) = [P(C6H4)Ph2]-), is described. Cleavage of this cluster with phosphines yields the mononuclear species Pd(PC)Br(P) in the form of cis and trans isomers. An equilibrium between mono- and tetranuclear species is observed for P = PCBr.

Multifaceted Palladium Catalysts Towards the Tandem Diboration–Arylation Reactions of Alkenes

“…General: PhI·Cl 2 [18] and the palladium complexes 1 a-d [9] and 4 a-b [14] were prepared by following reported methods. Commercially available reagents were purchased from Sigma-Aldrich.…”

“…[13] Under reaction conditions similar to those in Table 2 entry 1, moderate diol formation was observed, although the addition of one equivalent of NaOAc favoured the reaction quantitatively (Table 2, entries [13][14]. The presence of the carboxylate anion in the catalyst precursor does not seem to be critical for the cleavage of the diboron, as counterion BF 4 À also seems to contribute to this end, in view of entry 13 (Table 2) and the previously reported diboration reaction catalysed by Cu-NHC complexes.…”

“…[16] The new palladium species formed in situ is assigned to complex 4 a, in comparison with the NMR data of the previously isolated complex. [14] Following the synthetic methodology described in the literature, [14] pure complexes 4 a-b were prepared and used in the catalytic diboration reaction of vinylarenes so that their catalytic activities could be checked and compared with those observed for complexes 2 a-b. Interestingly, catalyst precursors 4 a-c proved to be as active and as chemoselective in the diboration/oxidation of styrene as complexes 2 ab (Table 4).…”

Cyclopalladated complexes containing 2-C6R4PPh2 ligands (R = H, F): one-electron electrochemical reduction leading to metal–carbon σ-bond cleavage via palladium(i)

“…For example, depending on the steric bulk of the auxiliary tertiary phosphine, planar palladium(II) complexes PdBr(2-C 6 H 4 PPh 2 )(PR 3 ) are either mononuclear, containing κ 2 -2-C 6 H 4 PPh 2 (I), for PR 3 = PPh 3 or PCy 3 , or dinuclear, containing μ 2 -2-C 6 H 4 PPh 2 (II), for PR 3 = PMe 3 ; for PR 3 = PMe 2 Ph, both structures coexist in solution. 2,3 In the case of palladium(II) with 2-C 6 F 4 PPh 2 , two complexes of the same composition, PdX(2-C 6 F 4 PPh 2 ) (X = Cl, Br), have been isolated: (III) is dinuclear with bridging halides and κ 2 -2-C 6 F 4 PPh 2 , 4,5 whereas (IV) is tetranuclear, with bridging halides and μ 2 -2-C 6 F 4 PPh 2 ; 6 (IV) appears to be thermodynamically more stable. Dipalladium(I) complexes are of continuing interest in view of their possible involvement, either directly or as precursors to Pd(0), in catalyzed C-C couplings such as the SuzukiMiyaura reaction.…”

Electrochemical chiral recognition by microparticle coatings of Pd complexes with bridging cyclometalated phosphines

“…This complex pertains to a family of recently synthesized palladium compounds [26][27][28] characterized by a paddlewheel structure (see Scheme 1) in which each palladium atom is bond to a carbon atom and a phosphorus one, each from a different (C 6 H 4 )PPh 2 ligand, and two oxygen atoms from two differScheme 1. Structure of the Pd 2 L 2 complex.…”