Synthesis of Ruthenium Polyhydride Clusters with 1,4,7-Triazacyclononane-Type Ligands: Stereo and Electronic Effects of Ancillary Ligands

Abstract

A ruthenium bis(η 2 -dihydrogen)-hydrido complex with 1,4,7-triazacyclononane (Cn), [CnRuH(H 2 ) 2 ]-(BPh 4 ) (2a-BPh 4 ), was prepared. The infrared spectra, longitudinal relaxation time (T 1 ) measurements, and density functional theory calculations reveal that the electron density at the metal center of complex 2a is higher than that of the 1,4,7-trimethyl-1,4,7-triazacyclononane (Cn*) analogue [Cn*RuH(H 2 ) 2 ] þ (2b). Complex 2a-BF 4 is converted into the tetranuclear octahydrido cluster complex [(CnRu) 4 (μ-H) 6 -(μ 3 -H) 2 ](BF 4 ) 4 (3-BF 4 ) via spontaneous dehydrogenation, whereas the dehydrogenation of 2b-PF 6 exclusively affords the diruthenium trihydrido complex [(Cn*Ru) 2 (μ-H) 3 ](PF 6 ) 2 (4-PF 6 ).

Polyhydrides of Platinum Group Metals: Nonclassical Interactions and σ-Bond Activation Reactions

“…Complex 164 is converted into the tetranuclear octahydride cluster compound [{(TACN)­Ru} 4 (μ-H) 6 (μ 3 –H) 2 ] 4+ ( 166 ), whereas the dehydrogenation of 165 affords the diruthenium-trihydride derivative [{(TACN*)­Ru} 2 (μ-H) 3 ] 2+ ( 167 ). Reactions of 165 with 5d-polyhydrides give rise to heterobimetallic dinuclear species. , …”

“…They have been mainly prepared through two procedures. Reduction of the ruthenium-(III) precursors RuCl 2 Tp(PR 3 ) (PR 3 = PPh 3 (143), P i PrPh 2 (144), P i Pr 3 (145), PCy 3 (146)) with NaBH 4 in a mixture of tetrahydrofuran-ethanol affords RuHTp(η 2 -H 2 )(PR 3 ) (PR 3 = PPh 3 (147), P i PrPh 2 (148), P i Pr 3 (149), PCy 3 (150)), 147 whereas the hydrogenation of RuHTp R (η 4 -COD) (Tp R = hydridetris(3,5-dimethylpyrazolyl)borate (Tp Me2 ; 151), hydridetris(3-isopropyl-4-bromopyrazolyl)borate (Tp′; 152)) in the presence of a monodentate ligand leads to RuHTp R (η 2 -H 2 )L (Tp R = Tp Me2 , L = PCy 3 (153), py (154), THT (155); Tp R = Tp′, L = PCy 3 (156), py (157), THT (158), NHEt 2 (159)). 148,149 The octahedral geometry of these compounds (Scheme 17) has been confirmed by the X-ray structure of 149.…”

Osmium(II)–Bis(dihydrogen) Complexes Containing Caryl,CNHC–Chelate Ligands: Preparation, Bonding Situation, and Acidity

“…The stability and chemical properties of the metal–dihydrogen interaction are further very sensitive to the position of the coligands in the metal coordination sphere . As a result, complexes containing two coordinated hydrogen molecules are rare, , in particular in the absence of hydride ligands, which exert a stabilizing cis -effect. , …”

Aluminum-Stabilized Low-Spin Iron(II) Hydrido Complexes of 1,4,7-Trimethyl-1,4,7-triazacyclononane

“…3 Despite these pioneering studies on the di-iron oxo complexes, little known are the corresponding hydrido forms having these ligand systems. Hitherto, the syntheses of the related dinuclear hydrido clusters of group 8 and 9 metals by Wieghardt, 4 our group, 5 Paneque, and Ruiz, 6 respectively, have involved [(Me 3 tacn) 2 Rh 2 (H) 2 (μ-H) 2 ] 2+ , [(Me 3 tacn) 2 M 2 (μ-H) 3 ] + (M = Fe, Ru), and [(Tp Me 2 ) 2 Ir 2 (H) 2 (μ-H)(μ-L)] (L = Cl, SC 4 H 3 ). We became intrigued with their reactivity toward unactivated substrates, compared to other ligand systems of Cp, CO, and triphos.…”