Ionic and Neutral Half‐Sandwich Guanidinatoruthenium(II) Complexes and Their Solution Behavior. Issue 19 (12th June 2015)

• Record Type: Journal Article
• Authors: Kishan, Ram; Kumar, Robin; Baskaran, Sambath; Sivasankar, Chinnappan; Thirupathi, Natesan
• Is Part Of: European journal of inorganic chemistry. Issue 19(2015)
• Page Start: 3182
• Page End: 3194
• Publication Date: 2015-06-12
• Subjects: Ruthenium -- Hydrogenation -- Rearrangement -- N ligands -- N–H activation; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201500395
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: Ionic and neutral half‐sandwich guanidinatoruthenium(II) complexes [(η 6 ‐C10 H14 )RuL(κ 2 ( N, N′ ){(ArN)2 C‐N(H)Ar})][OTf] [Ar = 4‐MeC6 H4, L = 2‐methylimidazole (1 ); Ar = 2‐MeC6 H4, L = 1, 3, 5‐triaza‐7‐phosphaadamantane (PTA;2 )], [(ArNH)3 C][(η 6 ‐C10 H14 )RuCl3 ] [Ar = 2‐ClC6 H4 (3 )] and [(η 6 ‐C10 H14 )RuCl(κ 2 ( N, N′ ){(ArN)2 C‐N(H)Ar})] [Ar = 2‐ClC6 H4 (4 ), 2‐FC6 H4 (5 ), 4‐ClC6 H4 (6 ), and 4‐(NO2 )C6 H4 (7 )] have been isolated and the molecular structures of all but6 were determined by single‐crystal X‐ray diffraction. VT 31 P{ 1 H} NMR spectroscopy of complex2 revealed the presence of a mixture of four isomers in a ratio of appproximately 1.4:11.0:1.6:0.1. Theoretical calculations were performed on the syn ‐ syn, syn ‐ anti, anti ‐ syn, and anti ‐ anti conformers of2, which revealed syn ‐ anti to be the most stable conformer, both in the gas phase and in solution. Furthermore, the energies relating to the interactions between the lone pairs of the nitrogen atoms of the CN3 unit and the antibonding orbital of the central carbon atom in the syn ‐ anti conformer of2 were investigated by NBO analysis. The 1 H NMR spectrum of3 reveals the presence of two species and their ratio is dependent upon the concentration of3 in CDCl3 and on the amount of D2 O in CD3 CN. The two species have been ascribed to the presence of a monomer and a water‐bridged dimer. The new complexes1 –7 were screened as pre‐catalysts in the transfer hydrogenation of acetophenone and complex3 was tested as a pre‐catalyst in the transfer hydrogenation of a variety of ketones to explore the scope of the reaction. Abstract : The guanidinate ligand in2 adopts the syn ‐ anti conformation in the solid state whereas in solution a mixture of syn ‐ anti, syn ‐ syn, anti ‐ syn, and anti ‐ anti conformations are observed, as detected by VT 31 P{ 1 H} NMR spectroscopy.