Formation of Cyclopentadienyl and Ruthenacyclopentadienyl Derivatives through Ynenyl-Diyne and Ynenyl-Alkyne Couplings onto a Triruthenium Cluster Core

Abstract

The compound [Ru3(mu-H)(mu3-eta2-ampy)(CO)9] (1; Hampy =2-amino-6-methylpyridine) reacts with diynes RC4R in THF at reflux temperature to give the ynenyl derivatives [Ru3(mu3-eta2-ampy)(mu-eta3-RC...CC-CHR)(mu-CO)2-(CO)6] (2: R=CH2OPh; 3: R=Ph). These products contain a 1,4-disubstituted butynen-3-yl ligand attached to two ruthenium atoms. The compound [Ru3(mu-eta2-ampy)[mu3-eta6-PhCC5(C...CPh)-HPh2](CO)7] (4), which contains an eta5-cyclopentadienyl ring and a bridging carbene fragment, has also been obtained from the reaction of 1 with diphenylbutadiyne. This compound arises from a remarkable [3+2] cycloaddition reaction of a preformed 1,4-diphenylbutynen-4-yl ligand with a triple bond of a second diphenylbutadiyne molecule. The reactivity of the ynenyl derivatives 2 and 3 with diynes and alkynes has been studied. In all cases, compounds of the general formula [Ru3(mu-eta2-ampy)[mu3-eta5-C(=CHR)C=CRCR1=CR2](CO)7] (5-17) have been obtained. They all contain a ruthenacyclopentadienyl fragment formed by coupling of the coordinated ynenyl ligand of 2 (R = CH2OPh) or 3 (R = Ph) with a triple bond of the new reagent (the CR1=CR2 fragment results from the incoming diyne or alkyne reagent). While most of the products derived from 2 have the alkenyl C=CHR fragment with a Z configuration (R cis to Ru), all the compounds obtained from 3 have this fragment with an E configuration. Except 2 and 3, all the cluster complexes described in this article have a five-electron donor ampy ligand attached to only two metal atoms, a coordination mode unprecedented in cluster chemistry.

Reactivity of a Triruthenium Ynenyl Cluster Complex with Diynes: Cluster-Mediated Combination of up to Three Substituted Butadiyne Molecules into a Carbon-Rich Hydrocarbyl Ligand

“…[9,11] A mechanistic proposal accounting for the formation of compounds similar to 2 from conjugated diynes and hydrido trinuclear clusters has been reported. [8] Apart from the above-mentioned ynenyl compounds derived from [Ru 3 (µ-Η)(µ 3 -η 2 -ampy)(CO) 9 ], [8] only a few more ynenyl derivatives have heretofore been reported as products of reactions of carbonylruthenium clusters with diynes, i.e. the compounds [Ru 2 (µ-NϭCPh 2 )(µ-η 2 -CH 2 ϭ CCH 2 CϵCSiMe 3 )(CO) 6 ], [12] [Ru 3 (µ 3 -η 2 -pyNMe)(µ-η 3 -PhCHϭCCϵCPh)(µ-CO) 2 (CO) 6 ], [11] and [Ru 4 (µ-η 2 -dmpz)(µ 4 -η 4 -MeCHϭCCϵCMe)(µ-CO)(CO) 10 ] (Hdmpz ϭ 3,5-dimethylpyrazole).…”

“…The structure depicted for this compound in Scheme 1, which shows a bridging threeelectron donor hex-2-yn-4-en-4-yl ligand, is also supported by the similarity of its spectroscopic data with those of the compounds [Ru 3 (µ 3 -η 2 -ampy)(µ-η 3 -RCHϭCCϵCR)-(µ-CO) 2 (CO) 6 ] (R ϭ Ph, CH 2 OPh), the structures of which have been determined by X-ray diffraction methods. [8] We have recently reported that the isolation of the 2-amido-6-methylpyridine derivative [Ru 3 (µ 3 -η 2 -ampy)(µ-η 3 -MeCHϭCCϵCMe)(µ-CO) 2 (CO) 6 ] could not be achieved. Although this complex was spectroscopically detected in the reaction of [Ru 3 (µ-Η)(µ 3 -η 2 -ampy)(CO) 9 ] with 2,4-hexadiyne, mixtures of inseparable products were always obtained, regardless of the ratio of the reactants.…”

“…The alternative product would have a hex-2-yn-4-en-5-yl ligand. This selectivity has also been observed previously for the reaction of compound 1 with 1,6-diphenoxy-2,4-hexadiyne, [8] but not with diphenylbutadiyne. [9,11] A mechanistic proposal accounting for the formation of compounds similar to 2 from conjugated diynes and hydrido trinuclear clusters has been reported.…”

“…Although a few hydrocarbyl ligands resulting from the coupling of two diyne molecules at metal cluster cores have (5) 1.131(7) C(6)ϪO (6) 1.139(7) C(7)ϪO (7) 1.127(7) C(8)ϪO (8) 1.129(7) C(9)ϪO(9) 1.138(6) C(10)ϪO (10) 1.138(6) C(11)ϪO(11) 1.176(6) C(12)ϪC (13) 1.356 (7) C (13)ϪC (14) 1.439(7) C(13)ϪC (17) 1.483 (7) C (14)ϪC (15) 1.199(9) C(16)ϪC (19) 1.438 (7) C (16)ϪC (24) 1.448(7) C(17)ϪC (18) 1.489 (6) C (17)ϪC (22) 1.326(7) C(18)ϪC (19) 1.404 (7) C (19)ϪC (20) 1.517 (7) (7) been reported, [8,9,15] complex 4 is the first example of a hydrocarbyl ligand resulting from the coupling of three diyne molecules. The compounds [Ru 3 (µ 3 -η 2 -ampy)(µ-η 3 -RCHϭ CCϵCR)(µ-CO) 2 (CO) 6 ] (R ϭ Ph, CH 2 OPh), structurally analogous to 2, are the only ynenyl derivatives whose reactivity with alkynes and diynes has been studied.…”

“…These ynenyl compounds are prone to react with alkynes and diynes to give interesting coupling products, including η 5 -cyclopentadienyl and η 5 -ruthenacyclopentadienyl derivatives. [8] However, the analogous ynenyl complex derived [ from [Ru 3 (µ-Η)(µ 3 -η 2 -ampy)(CO) 9 ] and 2,4-hexadiyne could not be isolated and, therefore, its reactivity could not be studied. [9] We report herein that the use of 2-aminopyrimidine (Hapyr) as a ligand precursor, instead of 2-amino-6-methylpyridine, leads to the isolation of a trinuclear ynenyl derivative of 2,4-hexadiyne, [Ru 3 (µ 3 -η 2 -apyr)(µ-η 3 -MeCHϭ CCϵCMe)(µ-CO) 2 (CO) 6 ], and allows the study of the reactivity of the latter complex with diynes.…”