[Ni(NHC)2] as a Scaffold for Structurally Characterized trans [H-Ni-PR2] and trans [R2P-Ni-PR2] Complexes

Sara Sabater, David Schmidt, Heidi Schmidt, Maximilian Kuntze-Fechner, Thomas Zell, Connie Isaac, Nasir Rajabi, Harry Grieve, William Blackaby, John Lowe, Suart Macgregor, Mary Mahon, Udo Radius, Michael Whittlesey

Research output: Contribution to journalArticlepeer-review

Abstract

Addition of PPh 2 H, PPhMeH, PPhH 2 , P( para -Tol)H- 2 , PMesH 2 and PH 3 to the two-coordinate Ni(0) N-heterocyclic carbene species [Ni(NHC) 2 ] (NHC = I i Pr 2 , IMe 4 , IEt 2 Me 2 ) affords a series of mononuclear, terminal phosphido Ni complexes. Structural characterisation of nine of these compounds show they exhibit unusual trans [H-Ni-PR 2 ] or novel trans [R 2 P-Ni-PR 2 ] geometries. The bis-phosphido complexes are more accessible when smaller NHCs (IMe 4 > IEt 2 Me 2 > I i Pr) and phosphines are employed. P-P activation of the diphosphines R 2 P-PR 2 (R 2 = Ph 2 , PhMe) provides an alternative route to some of the [Ni(NHC) 2 (PR 2 ) 2 ] complexes. DFT calculations capture these trends with P-H bond activation proceeding from unconventional phosphine adducts in which the H substituent bridges the Ni-P bond. P-P bond activation from [Ni(NHC) 2 (Ph 2 P-PPh 2 )] adducts proceeds with computed barriers below 10 kcal/mol. The ability of the [Ni(NHC) 2 ] moiety to afford isolable terminal phosphido products reflects the stability of the Ni-NHC bond that prevents ligand dissociation and onward reaction.

Original languageEnglish
JournalChemistry - A European Journal
Early online date30 Jun 2021
DOIs
Publication statusE-pub ahead of print - 30 Jun 2021

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