Ruthenacyclic Carbamoyl Complexes: Highly Efficient Catalysts for Organosilane Hydrolysis

Abstract

The ruthenacyclic carbamoyl complexes [RuX{2-NHC(O)C 5 H 3 NR}(CO) 2 (NCMe)] (R = H and Me; X = Br and SC 6 H 3o,o-Me 2 ) are excellent catalysts for the hydrolysis of organosilanes, particularly towards primary silanes, generating hydrogen [a]

Very strong trans effect in ruthenacyclic carbamoyl complexes leads to ligand redistribution in phosphine derivatives

“…The X-ray crystal structural determination of 3b has been reported previously [28], and those for 3a, 3b", 4a, 4a', 4b", 4c" and 5 are reported here. The ORTEP plots illustrating the molecular structures of 3b", 4b" and 5 are given in Figure 2, and selected bond parameters together with a common atomic labelling scheme for all these complexes are collected in Table 1.…”

“…Although a number of studies have shown that ruthenium complexes containing a four-membered metalla-heterocyclic ring are unexpectedly stable [28,29], the complex 2, which contains a chelating N,S-donor ligand [27], shows similar behaviour as 1 (Scheme 2). Thus, its reactions with one and two equivalents of PMe3 are instantaneous and give the mono-and di-adducts 3b" and 4b", respectively, via opening of the four-membered metalla-heterocyclic ring at the nitrogen atom; the analogous reaction with P(n-Bu)3, however, does require more forcing conditions (75 o C).…”

“…Chemicals were obtained from Sigma Aldrich and were used as received. The compounds 1, 2 and 3b were synthesized following literature procedures [26][27][28]. Solvents that were used for reactions were distilled over the appropriate drying agents under argon before use.…”

“…A large variety of ironbased model complexes for the metal cofactor have been reported [8][9][10][11][12][13][14][15][16][17][18], including some which mimic the function of the natural enzyme [19][20][21][22]. Since ruthenium complexes are known to catalyse a wide variety of reactions that utilise or involve hydrogen or hydrogenation [23][24][25], we thought that it made sense to also examine ruthenium-based structural mimics such as 1 and 2 (Figure 1b), which we have reported earlier [26][27][28]. In what appeared to be a straightforward study, we looked at the reactivity of the complexes 1/1' and 2 with phosphine ligands as a general assessment of their chemical reactivity.…”

Group VIII carbamoyl complexes as catalysts for alkyne hydrocarboxylation and electrochemical proton reduction

“…8,9,10,11 We recently reported the synthesis and physical properties of metallacyclic carbamoyl complexes 1n as structural analogues of this cofactor for the group VIII triad, viz., iron, ruthenium and osmium (Figure 1b). 12,13,14 An interesting aspect of these complexes is that the 2mercaptopyridine ligand is hemilabile; it imparts stability to the complexes and yet is capable of decoordination at the pyridine-N. 12 This property makes the complexes potential catalysts and indeed, as we would like to report here, they are efficient catalysts for alkyne hydroxycarboxylation and electrochemical proton reduction.…”