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The addition of PPh2H, PPhMeH, PPhH2, P(para‐Tol)H2, PMesH2 and PH3 to the two‐coordinate Ni0 N‐heterocyclic carbene species [Ni(NHC)2] (NHC=IiPr2, IMe4, IEt2Me2) affords a series of mononuclear, terminal phosphido nickel complexes. Structural characterisation of nine of these compounds shows that they have unusual trans [H−Ni−PR2] or novel trans [R2P−Ni−PR2] geometries. The bis‐phosphido complexes are more accessible when smaller NHCs (IMe4>IEt2Me2>IiPr2) and phosphines are employed. P−P activation of the diphosphines R2P−PR2 (R2=Ph2, PhMe) provides an alternative route to some of the [Ni(NHC)2(PR2)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(Ph2P−PPh2)] adducts proceeds with computed barriers below 10 kcal mol−1. 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. [ABSTRACT FROM AUTHOR]

Treatment of [Ru(PPh 3 )(C 6 H 4 PPh 2 ) 2 H][Li(THF) 2 ] with AlMe 2 Cl and SnMe 3 Cl leads to elimination of LiCl and CH 4 and formation of the heterobimetallic complexes [Ru(C 6 H 4 PPh 2 ) 2 {PPh 2 C 6 H 4 AlMe(THF)}H] 5 and [Ru(PPh 3 )(C 6 H 4 PPh 2 )(PPh 2 C 6 H 4 SnMe 2 )] 6 , respectively. The pathways to 5 and 6 have been probed by variable temperature NMR studies, together with input from DFT calculations. Complete reaction of H 2 occurs with 5 at 60 °C and with 6 at room temperature to yield the spectroscopically characterized trihydride complexes [Ru(PPh 2 ) 2 {PPh 2 C 6 H 4 AlMe}H 3 ] 7 and [Ru(PPh 2 ) 2 {PPh 2 C 6 H 4 SnMe 2 }H 3 ] 8 . In the presence of CO, 6 forms the acylated phosphine complex, [Ru(CO) 2 (C(O)C 6 H 4 PPh 2 )(PPh 2 C 6 H 4 SnMe 2 )] 9 , through a series of intermediates that were identified by NMR spectroscopy in conjunction with 13 CO labeling. Complex 6 undergoes addition and substitution reactions with the N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene (IMe 4 ) to give [Ru(IMe 4 ) 2 (PPh 2 C 6 H 4 )(PPh 2 C 6 H 4 SnMe 2 )] 10 , which converted via rare N-Me group C-H activation to [Ru(IMe 4 )(PPh 3 )(IMe 4 )'(PPh 2 C 6 H 4 SnMe 2 )] 11 upon heating at 60 °C and to a mixture of [Ru(IMe 4 ) 2 (IMe 4 )'(PPh 2 C 6 H 4 SnMe 2 )] 12 and [Ru(PPh 3 )(PPh 2 C 6 H 4 )(IMe 4 -SnMe 2 )'] 13 at 120 °C., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The 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=IiPr 2 , IMe 4 , IEt 2 Me 2 ) affords a series of mononuclear, terminal phosphido nickel complexes. Structural characterisation of nine of these compounds shows that they have 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 >IiPr 2 ) 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 -1 . 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., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The preparation and reactivity with H 2 of two Ru complexes of the novel ZnPhos ligand (ZnPhos = Zn( o -C 6 H 4 PPh 2 ) 2 ) are described. Ru(ZnPhos)(CO) 3 ( 2 ) and Ru(ZnPhos)(IMe 4 ) 2 ( 4 ; IMe 4 = 1,3,4,5-tetramethylimidazol-2-ylidene) are formed directly from the reaction of Ru(PPh 3 )(C 6 H 4 PPh 2 ) 2 (ZnMe) 2 ( 1 ) or Ru(PPh 3 ) 3 HCl/LiCH 2 TMS/ZnMe 2 with CO and IMe 4 , respectively. Structural and electronic structure analyses characterize both 2 and 4 as Ru(0) species in which Ru donates to the Z-type Zn center of the ZnPhos ligand; in 2 , Ru adopts an octahedral coordination, while 4 displays square-pyramidal coordination with Zn in the axial position. Under photolytic conditions, 2 loses CO to give Ru(ZnPhos)(CO) 2 that then adds H 2 over the Ru-Zn bond to form Ru(ZnPhos)(CO) 2 (μ-H) 2 ( 3 ). In contrast, 4 reacts directly with H 2 to set up an equilibrium with Ru(ZnPhos)(IMe 4 ) 2 H 2 ( 5 ), the product of oxidative addition at the Ru center. DFT calculations rationalize these different outcomes in terms of the energies of the square-pyramidal Ru(ZnPhos)L 2 intermediates in which Zn sits in a basal site: for L = CO, this is readily accessed and allows H 2 to add across the Ru-Zn bond, but for L = IMe 4 , this species is kinetically inaccessible and reaction can only occur at the Ru center. This difference is related to the strong π-acceptor ability of CO compared to IMe 4 . Steric effects associated with the larger IMe 4 ligands are not significant. Species 4 can be considered as a Ru(0)L 4 species that is stabilized by the Ru→Zn interaction. As such, it is a rare example of a stable Ru(0)L 4 species devoid of strong π-acceptor ligands.