Metallacycles of 1,4-Bis(3-thiophenyl)-1,3-butadiyne in Mixed Metal Clusters Derived by C−C Bond Coupling of Alkynyls

Abstract

Reaction of cis-Pt(C⋮CTp)2(dppe) (Tp = thiophene) with Ru3(CO)11(CH3CN) in refluxing toluene for 1 h resulted in head-to-head C−C bond coupling of the alkynyl ligands forming 1,4-bis(3-thiophenyl)buta-1,3-diyne, which afforded an extraordinal 1,4-heterodimetalla[5,6-b]thienopentalene, [PtRu3{μ4-η1:η1:η1:η1:η4:η4-C4H2S-CCC(H)CTp}(μ-CO)2(CO)6(dppe)] (1) (Tp = 3-thiophene), in 54% yield. Its crystal structure shows that a hydrogen shift occurs from the thiophene substituent to an end carbon atom of the 1,3-diyne, transforming 1,4-bis(3-thiophenyl)buta-1,3-diene, which results in formations of PtC4 and RuC4 rings, both with metallacyclopenta-2,4-diene. The Ru3(μ-CO)2(CO)6 moiety conforms to an open cluster, and its central ruthenium atom forms a RuCp ring whose carbon atoms bond to two ruthenium atoms by eight Ru−C π-bonds. Reactions of the acetylides with single metal media, Fe(CO)5, gave rise to annealation of alkynyls via both cyclic and acyclic dimerization processes, affording extraordinal metallacycles of 1,3-diyne, a platinacyclobutene consisting of a cyclone, [FePt{μ2-η1:η1:η4-(C4Tp2-CO)-CO}(CO)3(dppe)] (2), and a 1,2-heterodimetallacyclo-3-penten-5-one, [FePt(μ2-η1:η1:η2-TpCCCCTp-CO)(μ-CO)(CO)2](dppe)] (3), in 15 and 16% yields, respectively.

Synthesis and Structural Characterization of SiO2-Supported PtFe Catalysts Prepared from PtFe2(C8H12)(CO)8

“…A comparison of these data with those reported previously for conventionally-prepared Pt/SiO 2 and PtFe/SiO 2 samples with similar Pt and Fe loadings indicate that the light-off curves characterizing both cluster-derived samples are shifted to lower temperatures by approximately 50°C [34]. Consistent with previous literature reports [32][33][34][35][36][37], this result indicates that Fe improves considerably the catalytic performance of Pt for the oxidation of CO.…”

“…The synthesis of mixed organometallic PtFe clusters of different compositions is known for years [18,35]. However, only a limited number of such clusters have been used so far for the preparation of supported PtFe catalysts.…”

Crystal Structure of a Mixed Metal Compound Cross-Linked by 2-Ethynylpyridine, [PtRu3(.MU.4-.ETA.1:.ETA.2:.ETA.2-C.IDN.CPy-.KAPPA.N)(.ETA.1-C.IDN.CPy)(CO)9(PMe2Ph)2]

“…One ethynylpyridine in Pt(h 1 -C∫CPy)2(PMe2Ph)2 underwent a rearrangement, and now overbridges onto the cluster nuclei by (h In the present compound, the bond distance of Pt-C3, is 1.975(10)Å, which is more shortened from the corresponding distances, 2.078(8) and 2.054(9)Å, of [PtRu3{m4-C4H2S-C=CC(H)=CTp}(CO)8(dppe)], 7 indicating that the central metal atom of the present [Pt(h 1 -C∫CPy)(PMe2Ph)2]-moiety may be electronically enhanced in a positive character. Ethynyl carbon atoms of the other rearranged alkynyl-group newly overbridge onto the triangular cluster nuclei by totally (1s, 4p) bonds through a perpendicular coordination (Fig.…”

Crystal structure of dicarbonyl[μ2-methylenebis(diphenylphosphane)-κ2P:P′][μ2-2-(2,4,5-trimethylphenyl)-3-oxoprop-1-ene-1,3-diyl](triphenylphosphane-κP)ironplatinum(Fe—Pt)–dichloromethane–toluene (1/1/2), [(OC)2Fe(μ-dppm)(μ-C(=O)C(2,4,5-C6H2Me3)=CH)Pt(PPh3)]

“…The first step involves formation of a kinetic isomer [(OC) 2 Fe(-dppm){-C( O)C(H) C(Ar)}Pt(PPh 3 )], which then evolves to the thermodynamic one [(OC) 2 Fe(-dppm)-{-C( O)C(Ar) C(H)}Pt(PPh 3 )]. Other strategies leading to structurally characterized dimetallacyclopentones have been reported by Yamazaki et al (2005Yamazaki et al ( , 2006, implying the reaction of Fe(CO) 5 with the -alkyne-Pt 0 complex Pt( 2 -PhC CC CPh)(PPh 3 ) 2 or the bis-acetylide-Pt II compound Pt(C CTp) 2 (dppe) (Tp = 3-thiophene, dppe = 1,2-bis(diphenylphosphino)ethane), and leading to [(OC) 3 Fe{-C( O)C(Ph) C(C C-Ph)}Pt(PPh 3 ) 2 ] and [(OC) 2 Fe(-CO){-C( O)C(Tp) C(C C-Tp)}Pt(dppe)], respectively.…”