Phosphine Control of the Oxidative Addition Chemistry of Tetrathiocins to Palladium(0): Characterization of Mono-, Di-, and Hexanuclear Palladium(II) Dithiolate Complexes

Abstract

The outcome of the oxidative addition reactions of bis(4',5'-dimethoxybenzo)-1,2,5,6-tetrathiocin to Pd2dba3 under microwave conditions is sensitive to the nature of the phosphine coreagent; the bidentate phosphines dppm, dppe, and dppf afford the mononuclear dithiolates (dmobdt)Pd(dppm) (4), (dmobdt)Pd(dppe) (2), and (dmobdt)Pd(dppf) (5), whereas more labile monodentate phosphines lead to aggregation; Ph3P afforded the dinuclear dithiolate (dmobdt)2Pd2(PPh3)2 (6), whereas (t)Bu3P generated the phosphine-free hexanuclear edge-capped octahedral complex Pd6(dmobdt)6 (7) [dmobdt = 4,5-dimethoxybenzenedithiolate, (MeO)2C6H2S2(2-)].

C2-isomer of [Pd(tfd)]6[tfd is S2C2(CF3)2] as its benzene solvate: a new member of the small but growing class of homoleptic palladium(II) monodithiolenes in the form of hexameric cubes

“…The gross features of this cube-like structure will be discussed first, followed by details such as bond lengths. The structure is of the hexametallic cube type seen previously in the hexameric homoleptic palladium monodithiolenes characterized by Stiefel and co-workers (Beswick et al, 2002), Stibrany (Stibrany, 2012), and Rawson and co-workers (Wrixon et al 2015). All structures have in common: (a) the cluster closely approximates a cube containing six Pd II atoms, one at the centre of each cube face; (b) 12 S atoms occupy the midpoint of all 12 cube edges, providing for each Pd II atom an approximately square-planar S 4 environment; (c) each S atom is part of a dithiolene molecule, where the size of the dithiolene ligand requires that only sulfurs on adjacent cube edges can be part of the same dithiolene.…”

“…This general cubetype framework has so far given rise to two isomer types: one S 6 -symmetric isomer seen for the charge-neutral palladium complex of S 2 C 2 (COOMe) 2 (Beswick et al, 2002) and for a partially reduced complex involving the same ligand (Stibrany, 2012). The charge-neutral complex Pd(dithiolene) 6 with the dithiolene S 2 C 6 H 2 (OMe) 2 was found by Rawson and coworkers (Wrixon et al, 2015) to have a different, C 2symmetric, structure. The two isomeric types are shown here schematically, inscribed into a cube (Fig.…”

“…The partially reduced complex, with a tetraphenylphosphonium counter-ion, was later structurally characterized by Stibrany (2012). A charge-neutral complex Pd(dithiolene) 6 with the ISSN 2056-9890 dithiolene S 2 C 6 H 2 (OMe) 2 was reported by Rawson and coworkers (Wrixon et al, 2015). In this work, we generated [Pd(tfd)] 6 [where tfd is the dithiolene S 2 C 2 (CF 3 ) 2 ] from tfd and the dibenzylideneacetone (dba) complex Pd 2 dba 3 as described below.…”

Synthesis of bis(trithio)phosphines by oxidative transfer of phosphorus(i)

“…These molecules have proven successful in regard to oxidative addition reactions with various late transition metals. [39][40][41][42] In this context, we suspected that these soft donors would be excellent candidates for oxidative addition reactions to the phosphorus(I) fragment in [P I dppe][Br].…”

Synthesis of Mono- and Diiron Dithiolene Complexes as Hydrogenase Models by Dithiolene Transfer Reactions, Including the Crystal Structure of [{Ni(S2C2Ph2)}6]

“…In the13 C NMR spectrum one would therefore expect to see six signals of equal intensity for the dithiolene carbons, and the same for the ipso carbons of the phenyl substituents. A total of twelve page 15 signals are observed in this region, implying that the solid state structure is maintained in solution.The molecule is chiral: as shown inFigure 7, when viewed from above Ni(1) the dithiolene ligands of each sulfur in the equatorial plane bridge to the nickel atom in a leftward direction, whereas its enantiomer would have the opposite direction (the molecule of Rawson's Pd 6 complex depicted in that paper is the right-handed enantiomer) 81.…”