Ru(II)-hydride-trop complexes: X-ray single-crystal determination and quantum-chemical calculations.

Abstract

As part of our search for catalytically active Ru(II)-hydride complexes, we have synthesized and crystallographically characterized three different ruthenium species, namely dihydrido[(SR)-(10,11-η)-N-(pyridin-2-ylmethyl-κN)-5H-dibenzo[a,d]cyclohepten-5-amine](triphenylphosphane-κP)ruthenium(II) tetrahydrofuran monosolvate, [RuH2(C21H18N2)(C18H15P)]·C4H8O or (SR)-[Ru(II)(H)2{N-(pyridin-2-ylmethyl)tropNH}(PPh3)]·THF, (1), chlorido{(1SR,2RS)-N,N'-bis[(10,11-η)-5H-dibenzo[a,d]cyclohepten-5-amine]ethane-1,2-diamine-κ(2)N,N'}hydridoruthenium(II) dimethoxyethane hemisolvate, [RuClH(C32H28N2)]·0.5C4H10O2 or (1SR,2RS)-[Ru(II)(H)(Cl){tropNH(CH2)2HNtrop}]·DME, (2), and chlorido{(1SR,2RS)-N,N'-bis[(10,11-η)-5H-dibenzo[a,d]cyclohepten-5-amine]propane-1,3-diamine-κ(2)N,N'}hydridoruthenium(II), [RuClH(C33H30N2)] or (1SR,2RS)-[Ru(II)(H)(Cl){tropNH(CH2)3HNtrop}], (3), where trop is 5H-dibenzo[a,d]cycloheptene. In all three complexes, the Ru(II) center resides in an octahedral coordination environment. For (1)-(3), the hydride atoms were located in a difference Fourier map and were refined freely. In solution, the (1)H NMR spectra of all species show the presence of the hydride resonance. Comparison with quantum-chemical calculations reveals that the crystallographic data sets are plausible. In every case, the prediction is in very good agreement with the observed X-ray data. Not only the observed geometry is predicted well but also the Ru-H(hydride) bond lengths are reproduced remarkably well. Complexes (1) and (2) crystallized in the triclinic P1 space group, while (3) crystallized in the tetragonal space group I4(1)/a. For (3), there is disorder of the axial ligands producing two isomers (in a 98.7:1.3 ratio). Details of the synthesis, characterization, X-ray analysis, and theoretical calculations for complexes (1)-(3) are presented.