金属有机化学反应与应用催化

1. Mononuclear ruthenium(II) complexes supported by 1,4,7-trimethyl-1,4,7-triazacyclononane (Me₃tacn) ligands

Treatment of ruthenium(II) precursor [(Me₃tacn)Ru(dmso)Cl₂] (Me₃tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, dmso = dimethylsulfoxide) (1) with concentrated HCl in the presence of air afforded a ruthenium(III) complex [(Me₃tacn)RuCl₃·H₂O] (2). Reaction of 2, 2,2′-bipyridine or substituted 2,2′-bipyridine, and zinc metal powder in the presence of sodium perchlorate gave the corresponding cationic aquaruthenium(II) complex [(Me₃tacn)Ru(R-bpy)(H₂O)](ClO₄)₂ (bpy = 2,2′-bipyridine, R = H, 3; 4,4′-Me₂, 4; 5,5′-Me₂, 5; 4,4′-di-^tBu, 6). The hydrate ligand in complexes 3 and 5 could be substituted by acetonitrile or pyridine forming complexes [(Me₃tacn)Ru(5,5′-Me₂-bpy)(CH₃CN)](ClO₄)₂ (7) and [(Me₃tacn)Ru(R-bpy)(py)](ClO₄)₂ (py = pyridine, R = H (8), R = 5,5′-Me₂ (9), respectively. Interaction of [(Me₃tacn)Ru(bpy)(H₂O)](PF₆)₂ with phenylacetylene in methanol afforded a ruthenium-carbene complex [(Me₃tacn)(bpy)Ru=C(OMe)CH₂Ph](PF₆)₂ (10). The photocatalysis properties of ruthenium complexes  for H₂ evolution by water splitting were also investigated in the paper.

   

Synthesis and reactivity of ruthenium complexes with Me₃tacn ligands.                            

Molecular structures of bipydine ruthenium conplexes

2. Adducts of ruthenium(IV) thiolates with substituted pyridines. Syntheses and structures of [Ru(SMes)₄(R-py)] (R = 4-Et, 4-^tBu, and 3,5-Me₂) and [{Ru(SMes)₄}₂(μ-4,4′-bipy)] (Mes = 2,4,6-trimethylphenyl)

Treatment of the trigonal-bipyramidal ruthenium(IV)–thiolate complex, [Ru(SMes)₄(MeCN)] (Mes = 2,4,6-trimethylphenyl, 1), with an anhydrous diethyl ether solution of hydrogen chloride in THF afforded [Ru(SMes)₃Cl(MeCN)] (2), whereas interaction of 1 with [Et₄N]Cl in THF gave an anionic ruthenium(IV)–thiolate complex, [Et₄N][Ru(SMes)₄Cl] (3). Reaction of 1 with one equivalent of substituted pyridines in dichloromethane gave the corresponding pyridine-coordinated ruthenium(IV)–thiolate complexes, [Ru(SMes)₄(R-py)] (R = 4-Et, 4; 4-^tBu, 5; 3,5-Me₂, 6), while reaction of 1 with 0.5 equiv. of 4,4′-bipy (4,4′-bipy = 4,4′-bipyridine) in dichloromethane resulted in the formation of a dinuclear ruthenium(IV)–thiolate complex [{Ru(SMes)₄}₂(μ-4,4′-bipy)] (7).

                            

Reactions of the ruthenium(IV)–thiolate complex [Ru(SMes)₄(MeCN)]

                                                       

Molecular structure of ruthenium complexes

3. Synthesis and characterization of ruthenium complexes with 1-aryl-2-mercaptoimidazole ligands

Reactions of the vinyl ruthenium starting material Ru(CH=CHPh)Cl(CO)(PPh₃)₂ (1) with 1-aryl-2-mercaptoimidazole (HLa, aryl = 4-chloro-phenyl; HLb, aryl = 4-methyl-phenyl; HLc, aryl = 4-nitrophenyl) in the presence of sodium methoxide in dichloromethane and methanol afforded [Ru(CH=CHPh)(ĸ²-L)(CO)(PPh₃)₂] (2a−2c). Treatment of 1 with HL in THF gave [RuCl(ĸ²-L)(CO)(PPh₃)₂] (3a−3c) contaminant with formation of styrene as byproduct. Interactions of 1 with HLa in dichloromethane led to isolation of a novel dinuclear ruthenium complex [(CO)(PPh₃)(CHNCH₂Ph)Ru(μ-Cl)₂(μ-S)RuCl(-CO)(PPh₃)] (4a) via N−H bond addition to styryl ligand.

                           

Synthesis of Ruthenium Complexes

                                                       

Molecular structure of ruthenium complexes

4. Syntheses, structures and immobilization of ruthenium complexes bearing N,O-Schiff-base or N,N′-diamine ligands functionalized with alkoxysilyl groups

Condensation of γ-aminopropyltriethoxysilane and substituted salicylaldehydes in ethanol afforded three new Schiff-base compounds [(EtO)₃Si(CH₂)₃N=CHArOH] (Ar = C₆H₄, L1H; C₆H₃(4-Cl), L2H; C₆H₂(2,4-^tBu₂), L3H). Treatment of [Ru(NO)Cl₃·xH₂O] with L1H in the presence of Et₃N in THF gave a ruthenium nitrosyl complex [RuCl₂(NO)(ĸ²-O,N-L1)(OEt₂)] (1) with a linear N≡O moiety. Reactions of [(η⁶-p-cymene)RuCl(μ-Cl)]₂ with L1H or L2H in the presence of AgNO₃ and Et₃N afforded complexes [(η⁶-p-cymene)RuCl(ĸ²-O,N-L)] (L = L1, 2; L2, 3). While reaction of [Ru(CO)₂Cl₂]_n and L3H in the presence of Et₃N afforded an anionic ruthenium complex (Et₃NH)[RuCl₂(CO)₂(ĸ²-O,N-L3)] (4). Treatment of alkoxysilyl functionalized N,N′-diamine compound N¹-(3-(trimethoxysilyl)propyl)ethane-1,2-diamine (L4) with [Ru(PPh₃)₃Cl₂] or [Ru(DMSO)₄Cl₂] (DMSO = dimethyl sulfoxide) or [Ru(COD)Cl₂]_x (COD = 1,5-cyclooctadiene) led to formation of complexes [Ru(PPh₃)₂Cl₂(ĸ²N-L4)] (5), [Ru(DMSO)₂Cl₂(ĸ²N-L4)] (6), and [Ru(COD)Cl₂(ĸ²N-L4)] (7). Immobilization of complexes 2 and 5 on SBA-15, and characterization of these hybrid heterogeneous catalysts were studied by transmission electron microscopy (TEM), IR and low pressure N₂ adsorption/desorption measurement. The heteroge-neous catalysts were also briefly tested for oxidation of benzyl alcohol to benzaldehyde.

                           

Syntheses of N,O-Schiff bases (L1H, L2H, L3H) and schematic representation of N,N′-diamine ligand L4.

                           

Syntheses of ruthenium complexes 1−4 with N,O-bidentate Schiff-base ligands bearing ethoxysilyl groups.

                           

Syntheses of ruthenium complexes 5−7 with N,N′-bidentate diamine ligands bearing methoxysilyl groups.