Reactions of Diacetylene Ligands with Trinuclear Clusters. 3. Cyclization of Diynes with β-Amino Moieties on the Metal Core of [H₂Os₃(CO)₁₀]

Abstract

Reactions of [H 2 Os 3 (CO) 10 ] with the substituted diynes R-C 5), and {µ-η 1 :η 1 -CH 3 CCdC-C(H)dC(H)-NPh} (6), which have been characterized by single-crystal X-ray diffraction analyses as well as by various spectroscopic methods. In clusters 4-6, the starting diynes 1-3 have been rearranged to form substituted pyrrolyl rings which bridge two osmium atoms in η 1 :η 2 -(4, 5) or η 1 :η 1 -(6) coordination modes depending on the nature of substituents in 1-3. A possible reaction pathway for the diyne cyclization reactions that yield 4-6 involves initial transfer of a hydride onto a coordinated diyne followed by a series of 1,3-shifts and subsequent nucleophilic attack of the nitrogen on the third carbon atom of the diyne system to afford the five-membered pyrrolyl ring. Cluster 6 and its previously characterized furanyl analogue [HOs 3 (CO) 10 {µ-η 1 :η 1 -(OCH-CHCC)-C-CH 3 )}] (7) undergo facile thermal transformation accompanied by the loss of a CO ligand to give the clusters [HOs 3 (CO) 9 {µ 3 ,η 3 -CH 3 CCdC-C(H)dC(H)-NPh}] (8) and [HOs 3 (CO) 9 {µ 3 ,η 3 -(OCHdCHCdCCCH 3 )}] (9). In both 8 and 9, single-crystal X-ray analysis revealed the presence of pentagonal pyramid cluster cores containing three osmium and three carbon atoms.

Molecular rearrangements of diynes coordinated to triosmium carbonyl clusters: reactions of [Os3(μ-H)2(CO)10] and [Os3(CO)10(MeCN)2] with 1,4-dipyridylbuta-1,3-diyne

“…17 The [HOs 3 (CO) 10 (Z 1 :Z 1 -OC 4 H 2 CCH 3 ] has been shown to undergo an aldol condensation reaction with aromatic aldehydes. 33 Similar cyclisation products have also been observed in the reaction of [Os 3 (m-H) 2 (CO) 10 ] with substituted diynes RCR 24,34 Reactions involving [Os 3 (m-H) 2 (CO) 10 ] and Me 3 SiCRC-CRCSiMe 3 do not result in cyclisation products due to the 1,2-shift of the SiMe 3 stabilising the ethynyl ligand. 19 Similarly, a 1,2-shift of one of the ferrocenyl groups along the butadiyne chain has been suggested to account for the products of the reaction of FcC 2 C 2 Fc with [Os 3 (m-H)(CO) 10 (m-Z 2 -NC 5 H 4 )].…”

“…[11][12][13][14][15][16] Recently, the reactions of 1,3-conjugated diynes with ruthenium and osmium clusters have attracted considerable interest because of the unusual transformations that these molecules undergo when they are attached to the cluster core. For the osmium systems, observed chemistry includes intramolecular rearrangement or cyclisation of the ligand under mild conditions [17][18][19][20][21][22][23] and carbon-carbon bond rupture in thermolysis reactions, 24 and related results are observed for ruthenium cluster systems. 25 The result of the ligand rearrangement generally depends essentially on the nature of the terminal substituents of the diyne.…”

“…Both molecules exhibit an indolizinyl ring system formed by H-transfer from the hydrido osmium cluster to the first carbon atom of the diyne followed by nucleophilic attack of one of the pyridyl nitrogen atoms on the third atom of the diyne (Scheme 1). A mechanism involving elimination of H 24 In the case of 1,4-dipyridylbuta-1,3-diyne the mechanism is simpler as no hydrogen migration or elimination occurs, although a similar product is obtained in each case.…”

Coordination Behavior and Transformations of Thienyl-Substituted Diacetylenes upon Coordination to Os3H2(CO)10

“…A similar coordination mode has been observed in other triosmium clusters. 7 Within the organic moiety the shortest bonds are those between C(21)C(22) at 1.342 (17) Å and between C(16)C(17) at 1.352(15) Å, while the longest bonds are C(11)C(12) 1.526 (14)Å and C(12)C(13) at 1.513 (14) Å. The carbonsulfur bonds range from 1.693(10) to 1.736(12) Å for C(13)S(1) and C(17)S(1) respectively.…”

Reaction of the diyne complex [Os3(μ-CO)(CO)9{μ3-η2-Me3SiCCCCSiMe3}] with phosphines and phosphites: Characterization of monophosphine substituted clusters [Os3(μ-CO)(CO)8(PR3){μ3-η2-Me3SiCCCCSiMe3}] (PR3=PPh3, P(OEt)3, PEt3, PHPh2 and Ph2PCH2PPh2)

“…Alkynes and diynes, as ligands, in ruthenium and osmium cluster chemistry are particularly interesting because of the versatility of their chemistry that leads to a range of products involving carbon-carbon bond formation, carbonyl insertion and a range of hydrogenated products depending on whether [M 3 (CO) 12 ] (M = Ru, Os), [M 3 (CO) 10 (NCMe) 2 ] or [Os 3 H 2 (CO) 10 ] is used as the cluster starting material [2]. Despite the plethora of cluster carbonyl complexes that contain diynes or their derivatives relatively little reaction chemistry has been carried out on the substituted complexes despite the presence of the diyne apparently activating the complex by comparison to the binary carbonyls [3][4][5][6][7]. In reported reactions of diyne-substituted cluster complexes decarbonylation as well as ligand rearrangement paths can occur.…”