Kinetic and Mechanistic Aspects of Sulfur Recovery from Pd₂I₂(μ-S)(μ-dpm)₂Using I₂and Structures of Pd(II) Complexes with the Chelated Monosulfide of dpm

Abstract

The Pd(2)X(2)(&mgr;-S)(dpm)(2) complexes (2) (X = I, Br) react with halogens to yield PdX(2)(dpm) (3) and elemental sulfur. Kinetic and mechanistic studies on the X = I system in CHCl(3) reveal that the reaction proceeds via addition of I(2) to give Pd(2)I(4)(dpm)(2) (4c), which then undergoes unimolecular decomposition to generate PdI(2)(dpm) (3c); the liberated sulfur concatenates to form elemental S(8). The addition reaction is in the stopped-flow time regime and is first-order in both 2c and I(2), with DeltaH() = 32 +/- 1 kJ mol(-)(1) and DeltaS() = -91 +/- 3 J K(-)(1) mol(-)(1). The slower decomposition reaction of 4c is first order in 4c, with DeltaH() = 80 +/-1 kJ mol(-)(1) and DeltaS() = -26 +/- 3 J K(-)(1) mol(-)(1). Byproduct PdX(2)(dpm(S)) (5) [dpm(S) = Ph(2)PCH(2)P(S)Ph(2)] also forms under some conditions via reaction of 3 with an S(n)() species (n < 8). Complexes 5 (X = Cl (a), Br (b), I (c)) were also synthesized directly, and the structure of the 5c species, as well as of [Pd(dpm(S))(2)]Cl(2), were determined by X-ray analyses that reveal the envelope configuration of the five-membered chelate ring.

Epimerization, diastereoselectivity and hemilability in dicationic chiral ruthenium complexes with bidentate (P∧S) bisphosphine monosulfide ligands

“…This phosphorus is coupled through the metal to the phosphorus nucleus of the arene-tethered ligand ( 2 J P-P = 35.7 Hz), as well as to the phosphine sulfide with J P-P = 19.7 Hz. This latter coupling is decreased with respect to the free ligand (49 Hz) [18], which is the usual observation [18][19][20][21][22] and is indicative of a spin coupling contribution of opposite sign through the metal and thus indicates the coordination of the sulfur to the metal. Likewise, the phosphine of the arene-tethered ligand shows a coupling to the directly coordinated phosphine of diphos(S), but an additional smaller 3 J coupling of 19.7 Hz to the phosphorus atom (the P V ) bound to the sulfur is observed.…”

Stepwise phosphine sulfide formation and metal-bridging reaction of tetradentate and tridentate phosphine ligands on palladium(II)

“…Some phosphine sulfides have been employed as monodentate or bidentate ligands for some metal ions [1][2][3][4][5][6], and we have applied multidentate phosphine sulfide ligands to the Pd(0) catalyzed CÀC coupling reaction to stabilize the zerovalent oxidation state of palladium [7]. However, so far, kinetic study on phosphine sulfide formation reactions of phosphine complexes has not been reported.…”

Synthesis and Carbonylation of Platinum(II) Organometallic Complexes with Bis(phosphanyl) Monosulfides − Crystal Structures of [κ2P,S‐{Ph2CH2P(S)Ph2}Pt(CH3)(Cl)] and [κP,μ‐κS‐{Ph2CH2CH2P(S)Ph2}Pt‐(CH3)]2[BF4]2

“…The usual [7,9,17,21] lowering in the bis(phosphanyl) monosulfide ( 31 P, 31 P) coupling constants is observed in both the neutral and cationic complexes: compared with the 2/3 J(P,P) of the free ligands [for dppmS 2 J(P,P) ϭ 79 Hz, for dppeS 3 J(P,P) ϭ 49 Hz], a decrease of 50 Hz and 41 Hz was found for 1 and 2 and a decrease of 55 Hz and 42 Hz was found for 3 and 4, respectively (Table 1).…”