The Pd (II) complexes trans-[PdCl 2 (μ-L)] 2 and [Pd(acac)(L)][BF 4 ] (L = RS (CH 2 ) 2 O(CH 2 ) 2 SR, R = Me, Et, n Pr, i Pr, n Bu, i Bu, n-hexyl, benzyl) were obtained through the reaction of Pd(cod)Cl 2 or [Pd(acac)(MeCN) 2 ][BF 4 ] with one equivalent of oxadithioether (L). The structural features of these complexes were analyzed by nuclear magnetic resonance (NMR) and Fouriertransform infrared spectroscopy (FTIR), as well as electrospray ionisation mass spectrometry and density functional theory calculations. The complexes diμ-(2,10-dimethyl-6-oxa-3,9-dithiaundecane-κ 2 S,S 0 )-bis[trans-dichloropalladium (II)] and (acetylacetonate-κ 2 O,O 0 )(2,10-dimethyl-6-oxa-3,9-dithiaundecane-κ 2 S, S 0 )palladium (II) tetrafluoroborate were characterized by X-ray diffractometry. The X-ray structures of each complex indicate an axial M-O interaction formed by the endodentate conformation of the oxadithioether ligand. Palladium (II) dichloride complexes with oxadithioethers were demonstrated to have a 16-membered dinuclear structure with a trans-configured S 2 PdCl 2 fragment. In the case of cationic palladium acetylacetonate complexes, only mononuclear complexes with a cis configuration of the oxadithioether fragment were observed. Variable temperature 1 H and 13 C NMR studies of the complexes demonstrate dynamic bonding of the oxadithioether ligands consistent with the presence of diastereoisomers that differ in the orientation of the S-R groups along with both endodentate and exodentate bonding modes in solution. FTIR studies of the complexes indicate the presence of isomers in the solid state. The palladium catalyst precursors trans-[PdCl 2 (μ-L)] 2 and [Pd (acac)(L)][BF 4 ] were found to be active in the addition polymerization of norbornene. In the presence of cocatalysts, such as diisobutylaluminum chloride and boron trifluoride etherate, Pd (II) complexes exhibited activities in the range of 10 5 to 10 7 g of polymer (mol of Pd) À1 h À1 . The catalyst systems
The Pd(II) complexes [Pd(Cp)(L)n]m[BF4]m were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF3∙OEt2 (n = 2, m = 1: L = PPh3 (1), P(p-Tol)3, tris(ortho-methoxyphenyl)phosphine (TOMPP), tri-2-furylphosphine, tri-2-thienylphosphine; n = 1, m = 1: L = dppf, dppp (2), dppb (3), 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: 1,6-bis(diphenylphosphino)hexane). Complexes 1–3 were characterized using X-ray diffractometry. The inspection of the crystal structures of the complexes enabled the recognition of (Cp–)⋯(Ph-group) and (Cp–)⋯(CH2-group) interactions, which are of C–H…π nature. The presence of these interactions was confirmed theoretically via DFT calculations using QTAIM analysis. The intermolecular interactions in the X-ray structures are non-covalent in origin with an estimated energy of 0.3–1.6 kcal/mol. The cationic palladium catalyst precursors with monophosphines were found to be active catalysts for the telomerization of 1,3-butadiene with methanol (TON up to 2.4∙104 mol 1,3-butadiene per mol Pd with chemoselectivity of 82%). Complex [Pd(Cp)(TOMPP)2]BF4 was found to be an efficient catalyst for the polymerization of phenylacetylene (PA) (catalyst activities up to 8.9 × 103 gPA·(molPd·h)−1 were observed)
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