Reaction Chemistry of Complexes Containing PtH, PtSH, or PtS Fragments: From Their Apparent Simplicity to the Maze of Reactions Underlying Their Interconversion

Abstract

The relevance of platinum in the reaction of thiophene and derivatives with homogeneous transition-metal complexes as models for hydrodesulfurization has led us to the study of the reaction chemistry of complexes containing Pt--H, Pt--SH, and Pt--S fragments. Exploration of the reactions triggered by addition of controlled amounts of Na2S or NaSH to [Pt2(H)2(mu-H)(dppp)2]ClO4 (1) has provided evidence of the formation of complexes [Pt2(mu-H)(mu-S)(dppp)2]ClO4 (2), [Pt(H)(SH)(dppp)] (3), [Pt2(mu-S)2(dppp)2] (4), [Pt2(mu-S)(dppp)2] (5) and [Pt(SH)2(dppp)], in which dppp denotes 1,3-bis(diphenylphosphanyl)propane. Consequently, complexes 1, 2, and 5 as well as the already reported 3, 4, and [Pt(SH)2(dppp)] have been obtained and fully characterized spectroscopically. Also the crystal structures of 1 and 2 have been solved. Complexes 1-5 constitute the main framework of the network of reactions that account for the evolution of 1 under various experimental conditions as shown in Scheme 1. Apparently, this network has complexes 2 and 4 as dead-ends. However, their reciprocal interconversion by means of the replacement of one bridging hydride or sulfide ligand in the respective {Pt(mu-H)(mu-S)Pt} and {Pt(mu-S)2Pt} cores enables the closure of the reaction cycle involving complexes 1-5. Theoretical calculations support the existence of the undetected intermediates proposed for conversion from 1 to 2 and from 3 to 2 and also account for the fluxional behavior of 1 in solution. The intermediates proposed are consistent with the experimental results obtained in comparable reactions carried out with labeled reagents, which have provided evidence that complex 1 is the source of the hydride ligands in complexes 2 and 3. Overall, our results show the strong dependence on the experimental conditions for the formation of complexes 1-5 as well as for their further conversion in solution.

C–S Bond Activation and Partial Hydrogenation of Thiophene by a Dinuclear Trihydride Platinum Complex

“…The synthesis and spectroscopic characterization of [(dppp) 2 The ESI-MS measurements were performed on a VG Quattro Micromass Instrument under already described experimental conditions. [50] The carrier was a 1:1 mixture of acetonitrile and water containing formic acid (1-10 %). The exact mass for III was determined on a micrOTOF-Q instrument using direct injection from HPLC 1200RR and Apollo II ESI ionization source.…”

“…The synthesis and NMR features of I-d 3 have already been reported. [50] On the whole the NMR features allowed identification of the compounds formed and eventually led to the synthesis and characterization of new complexes, as depicted in Scheme 3.…”

“…The set of reactions obtained provided solid evidence that behind the apparent simplicity of platinum complexes containing Pt-H, Pt-SH, or Pt-S fragments, there is an outstanding chemistry. [50] Results and Discussion…”

Progress toward the Isolation of Late Metal Terminal Sulfides

“…Finally, treatment of [(dppp)Pt(H)(SH)] ( 57 , dppp = 1,3 ‐ bis(diphenylphosphanyl)propane) with excess NaOH in MeCN results in isolation of [(dppp)Pt] 2 (µ 2 ‐S) 2 ( 59 ), concomitant with formal loss of H – . Calculations suggest that the reaction proceeds via an unobserved terminal sulfide intermediate, [(dppp)Pt(H)(S)] – ( 58 ) …”

S–S Bond Activation in Multi‐Copper ­Aggregates Containing Perthiocarboxylato Ligands

“…[47][48][49][50][51] This prompted us to evaluate the reactivity of 2 with NaBH 4 in CH 3 CN at room temperature. [47][48][49][50][51] This prompted us to evaluate the reactivity of 2 with NaBH 4 in CH 3 CN at room temperature.…”