Synthesis and Coordination Chemistry of a Tridentate o-Phenylene-Bridged Diphosphine−NHC System

Abstract

The preparation of a di-o-phenylene-bridged tridentate PCP donor set is described starting with t-BOCaniline followed by a series of steps that include lithiation, quenching with Pr i 2 PCl, conversion to the phosphine sulfide, and assembling the unsaturated N-heterocyclic carbene unit. After desulfurization, the imidazolinium unit flanked by two phosphine units, represented as [(PCP)H]PF 6 is obtained. Subsequent reaction with group 10 M(0) reagents (Ni(COD) 2 , Pd(PPh 3 ) 4 , and Pt(PPh 3 ) 4 ) generates good yields of the corresponding metal hydride complexes, [(PCP)MH]PF 6 salts (where M ) Ni(II), Pd(II), and Pt(II)). Each of these species has been characterized by elemental analyses, NMR spectroscopy, and X-ray crystallography. All of the structures show that the PCP unit is twisted with respect to the square plane of the d 8 metal complex.Supporting Information Available: Crystallographic data for 3, 7a, 7b, and 7c (CIF files); experimental details for X-ray structure determinations. This information is available free of charge via the Internet at http://pubs.acs.org. OM9000764 (45) Gilbertson, S. R.; Wang, X.

Synthetic Routes to N-Heterocyclic Carbene Precursors

“…The classical trialkylorthoformate route followed by reduction of the sulfides led to the bis-(phosphine) imidazolinium salt 33. 60 Gautier and co-workers recently showed that the "classical" SIMes imidazolinium salt could be obtained in 53% overall yield by using this alkylating route. Reaction of mesitylamine with 1,2-dibromoethane was efficiently conducted in methanol as solvent.…”

Nickel N-heterocyclic carbene complexes and their utility in homogeneous catalysis

“…There is an isolated report of the use of the oxidation method (Scheme 15) reported for the preparation of the (772) [237] from the reaction of the imidazolinium salt and Ni(COD) 2 .…”

Neutral Tridentate PNP Ligands and Their Hybrid Analogues: Versatile Non‐Innocent Scaffolds for Homogeneous Catalysis

“…These ligands range from the ubiquitous 2,2',6',2''-terpyridine [23] (tpy, 6 in Figure 2) to bis-(imino)pyridine systems 7, studied for late-transition-metal alkene polymerizations, [24] and related pyridine-based scaffolds such as 8 [25] and 9. [26] Other neutral tridentate frameworks, including structures 10 [27] and 11, [28] have also recently been developed, but little emphasis has so far been placed on catalytic applicability of these systems.…”