Phosphines with N‐Heterocyclic Boryl‐Substituents: Ligands for Coordination Chemistry and Catalysis. Issue 11 (16th November 2018)

• Record Type: Journal Article
• Authors: Kaaz, Manuel; Locke, Ralf J. C.; Merz, Luisa; Benedikter, Mathis; König, Simon; Bender, Johannes; Schlindwein, Simon H.; Nieger, Martin; Gudat, Dietrich
• Other Names: Gudat Dietrich guestEditor.; Orthaber Andreas guestEditor.; Slootweg J. Chris guestEditor.; Streubel Rainer guestEditor.
• Is Part Of: European journal of inorganic chemistry. Issue 11/12(2019)
• Page Start: 1586
• Page End: 1593
• Publication Date: 2018-11-16
• Subjects: Phosphane ligands -- Ligand effects -- Cross‐coupling -- Palladium -- Boranes; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201801081
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Boryl‐substituted phosphines NHB–P(R)Ph (R = H, Ph, NHB = N‐heterocyclic boryl substituent) react with Fe2 (CO)9 to give isolable Fe(CO)4 complexes, two of which were characterized by single‐crystal XRD studies. The electronic and steric properties for a series of the boryl phosphines were further assessed by evaluation of TEPs for in‐situ formed complexes [RhCl(NHB–PR 1 R 2 )(CO)2 ] (R 1, R 2 = H, Ph, Me, NMe2 ), and calculations of buried volumes for Fe(CO)4 complexes. The results imply that the NHB‐phosphines exhibit due to their conformational flexibility some variability in their steric bulk, and that some specimens may exhibit similar electron releasing power and steric demand as t Bu3 P. Studies of the amination of bromobenzene with 2, 6‐diisopropylaniline confirmed that these properties can be exploited to promote Pd‐catalyzed C–N cross coupling reactions, and that formal replacement of a phenyl by a NHB substituent in the auxiliary phosphine has a beneficial effect on catalyst performance. Abstract : Phosphines with an N‐heterocyclic boryl substituent at phosphorus behave as strongly electron releasing ligands that may impart despite their conformational flexibility sizeable steric shielding to a transition metal atom. This makes them suitable candidates for application as ligands in cross‐coupling chemistry.