Reactions at the Ru–S Bonds of Coordinatively Unsaturated Ruthenium Complexes with Tethered 2,6‐Dimesitylphenyl Thiolate

Abstract

Coordinatively unsaturated ruthenium complexes with a tethered SDmp (Dmp=2,6-dimesitylphenyl) ligand, [(DmpS)Ru(PR(3))][BAr(F) (4)] (3 a: R=Et; 3 b: R=Ph; Ar(F)=3,5-(CF(3))(2)C(6)H(3)), were synthesized by the reactions of [{(p-cymene)RuCl}(2)(mu-Cl)(2)], LiSDmp, phosphines, and NaBAr(F) (4). The Ru--S bonds in 3 a and 3 b were found to serve as the polarized reactive site in reactions with alkyl halides, diazoalkanes, (p-tosyliminoiodo)benzene, phenylacetylene, and H(2). Alkylation of 3 a and 3 b with methyl iodide or ethyl bromide occurred instantaneously to give the thioether complexes [(DmpSR')RuX(PR(3))][BAr(F) (4)] (4 a: R=Et, R'=Me, X=I; 4 b: R=R'=Et, X=Br; 4 c: R=Ph, R'=Me, X=I; 4 d: R=Ph, R'=Et, X=Br). Treatment of 3 a with diazoalkanes N(2)CHR (R=CO(2)Et, SiMe(3)) led to the cycloaddition of carbenes to the Ru--S bond to form [DmpS(CHR)Ru(PEt(3))][BAr(F) (4)] (5 a: R=CO(2)Et; 5 b: R=SiMe(3)), whereas the reaction with (p-tosyliminoiodo)benzene gave rise to [DmpS{NS(O)(C(6)H(4)-4-CH(3))O}Ru(PEt(3))][BAr(F) (4)] (6), which contains a five-membered ruthenacycle of RuSNSO. Addition of phenylacetylene to the Ru--S bond occurred reversibly to produce the vinyl sulfide complexes [DmpS(PhCCH)Ru(PR(3))][BAr(F) (4)] (7 a: R=Et; 7 b: R=Ph). On the other hand, the phenylacetylene at ruthenium slowly isomerized to vinylidene and bridged Ru and S in the products, [DmpS{C(CHPh)}Ru(PR(3))][BAr(F) (4)] (8 a: R=Et; 8 b: R=Ph). Complex 3 a catalyzed the hydrogenation of acetophenone, in which the heterolytic H-H splitting at the Ru-S site is suggested to be involved in the mechanism.

Hydrogenation and Transfer Hydrogenation Promoted by Tethered Ru−S Complexes: From Cooperative Dihydrogen Activation to Hydride Abstraction/Proton Release from Dihydrogen Surrogates

“…[6] Cooperative HÀH bond activation at the RuÀS bond in tethered thiolate complexes I is believed to yield dihydrogen adduct II with the protonated sulfur atom (I!II, Scheme 1). [2] A different approach to arrive at II would be to exploit the Lewis acidity of I at the ruthenium center and its Lewis basicity at the sulfur atom in two independent steps (Scheme 1). The reaction of coordinatively unsaturated II with cyclohexa-1,4-dienes of type III could lead to neutral hydride complexes IV and Wheland complexes V (I!IV and III!V).…”

“…Thiolate complexes 1 [1] and 2, [2] introduced by Ohki and Tatsumi, were shown to activate dihydrogen ( Figure 1). [3] The reactivity of the RhÀS bond in 1 is particularly noteworthy because it splits dihydrogen at À50 8C, [1] and also enables the reduction of C=O and C=N groups under ambient dihydrogen pressure at this temperature.…”

“…[3] The reactivity of the RhÀS bond in 1 is particularly noteworthy because it splits dihydrogen at À50 8C, [1] and also enables the reduction of C=O and C=N groups under ambient dihydrogen pressure at this temperature. [4] Likewise, the more-robust tethered complex 2 promotes dihydrogen activation [2,5] at room temperature, and C=O [2] reduction occurs under higher dihydrogen pressure (10 atm). [6] Cooperative HÀH bond activation at the RuÀS bond in tethered thiolate complexes I is believed to yield dihydrogen adduct II with the protonated sulfur atom (I!II, Scheme 1).…”

A model for the CO-inhibited form of [NiFe] hydrogenase: synthesis of (CO) 3 Fe( μ -S t Bu) 3 Ni{SC 6 H 3 -2,6-(mesityl) 2 } and reversible CO addition at the Ni site

“…1), which has attracted inorganic and organometallic chemists attempting to model both the structure and physicochemical properties. Thiolate-bridged Ni-Fe complexes have been synthesized as structural models of the active site (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26), and sulfurligated mono-and dinuclear transition metal complexes have been reported to promote H 2 activation mimicking the function of [NiFe] hydrogenase (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41). However, synthesis of better structural/functional models remains challenging.…”

Katalytische elektrophile C‐H‐Silylierung von Pyridinen ermöglicht durch vorübergehende Aufhebung der Aromatizität

“…[11,14,15] Der tatsächliche C-H-Silylierungsvorgang (Schritt 2) findet auf der Stufe des dearomatisierten Pyridins,d .h.d es 1,4-Dihydropyridins II,statt. Alle Schritte werden vom gleichen Katalysator, dem thiolatverbrückten Ru-S-Komplex V [16] (d. h. 2, Schema 2) herbeigeführt. Die Ru-S-Bindung in V spaltet die Si-H-Bindung von Hydrosilanen in ein Metallhydrid und ein schwefelstabilisiertes Siliciumkation (V!VI).…”