Bulky N-phosphinomethyl-functionalized N-heterocyclic carbene chelate ligands

• Verfasst von: Salem, Hiyam [VerfasserIn]
• Verfasst von: Schmitt, Martin [VerfasserIn]
• Verfasst von: Herrlich, Ulrike [VerfasserIn]
• Verfasst von: Kühnel, Erik [VerfasserIn]
• Verfasst von: Brill, Marcel [VerfasserIn]
• Verfasst von: Nägele, Philipp [VerfasserIn]
• Verfasst von: Bogado, André Luiz [VerfasserIn]
• Verfasst von: Rominger, Frank [VerfasserIn]
• Verfasst von: Hofmann, Peter [VerfasserIn]
• Titel: Bulky N-phosphinomethyl-functionalized N-heterocyclic carbene chelate ligands
• Titelzusatz: synthesis, molecular geometry, electronic structure, and their ruthenium alkylidene complexes
• Verf.angabe: Hiyam Salem, Martin Schmitt, Ulrike Herrlich (née Blumbach), Erik Kühnel, Marcel Brill, Philipp Nägele, André Luiz Bogado, Frank Rominger, and Peter Hofmann
• E-Jahr: 2013
• Jahr: January 2, 2013
• Umfang: 18 S.
• Fussnoten: Gesehen am 26.01.2022
• Titel Quelle: Enthalten in: Organometallics
• Ort Quelle: Washington, DC : ACS Publ., 1982
• Jahr Quelle: 2013
• Band/Heft Quelle: 32(2013), 1, Seite 29-46
• ISSN Quelle: 1520-6041
• DOI: doi:10.1021/om300487r
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 178719986X

Abstract

A new, extremely bulky, and electron-rich N-phosphinomethyl-functionalized N-heterocyclic carbene ligand, 5a (tBuNHCPtBu), and a somewhat less bulky congener, 5b (MesNHCPtBu), forming five-membered chelate rings with metal centers, have been synthesized in four steps starting from the easily accessible di-tert-butyl(hydroxymethyl)phosphine oxide (1). 5a was isolated and fully characterized by spectroscopic methods including UV-photoelectron spectroscopy and X-ray diffraction. The reaction of 5a with [Ru(COD)Cl2]n under hydrogen pressure or with [Ru(p-cymene)Cl2]2 led to the formation of the unsaturated dinuclear complex [Ru(tBuNHCPtBu)(μ-Cl)(Cl)]2 (6), which serves as a precursor for a series of ruthenium carbene complexes (7a-f) using substituted phenyldiazomethanes (p-X-C6H4(CH)N2; X = H (a), Br (b), CF3 (c), NO2, (d), CH3 (e)) and trimethylsilyldiazomethane (f). Treatment of 6 with phosphine or pyridine ligands led to the formation of the mononuclear adducts, [Ru(tBuNHCPtBu)(Cl2)(PR3)] (R = Me (8), Ph (9), Cy (10)) and [Ru(tBuNHCPtBu)(Cl2)(py)n] (n = 1 (11), 2 (12); if (py)2 = bipy (13)), which were synthesized in order to find alternative precursor complexes because the dimer 6 showed very low solubility in most organic solvents. Complex 7a was obtained analytically pure on a different route via transmetalation from a silver complex bearing tBuNHCPtBu (15) to the first-generation Grubbs catalyst as the ruthenium precursor. Complexes 7a-c and 7e were characterized by X-ray diffraction analysis, revealing a geometry that can be viewed as both a distorted square pyramid and a distorted trigonal bipyramid with the two chloro ligands in a cis configuration. The steric bulk, especially of 5a with its N-tBu moiety, stabilizes 16 VE Ru complexes. In contrast to ligand 5a, the somewhat less bulky MesNHCPtBu ligand 5b has allowed its direct metalation with two ruthenium alkylidene precursors, affording the two new carbene complexes 17 and 18.