Ruthenium dihydridobis(pyrazolyl)borate complexes adopting a kappa(3) N,N,H, kappa(2) N,H, or kappa(2) N,N bonding mode

Ruthenium complexes containing the dihydridobis(3,5-bis(trifluromethyl)pyra zolyl)borate ligand Bp((CF3)2) have been prepared and structurally characte rized. Reaction of (Bp((CF3)2))RuH(COD) (1a) with 2 equiv of bulky phosphin es PR3 under 3 bar of H-2 produces the hydrido(dihydrogen) complexes (Bp((C F3)2)RuH(H-2)(PR3)(2) (R = Cy, 2a; R = Pr-i, 3a). X-ray structural analysis of 3a confirms a kappa(2) N,H bonding mode of the Bp(CF3)2 ligand. In the absence of dihydrogen, the monohydride complex (Bp((CF3)2))RuH(COD)(PCy3) ( 4a) is isolated. Upon pressurization to 3 bar H-2, 4a converts into (Bp((CF 3)2))RuH(H-2)(PCy3) (5a) with rechelation of the pendant pyrazolyl ring and hydrogenation of the COD ligand, Addition of 2 equiv of PPh3 or Ppyl(3) to 1a under 3 bar of H-2 leads to the formation of the corresponding hydride complexes (Bp((CF3)2))RuH(PR3)(2) (R = Ph, 6a; R = pyl, 7a). Under similar conditions, 1a reacts with 2 equiv of (BuNH2)-Bu-t to produce the amine add uct (Bp((CF3)2))RuH((BuNH2)-Bu-t)(2) (8a). By addition of 1 equiv of MeI to 8a, the iodo complex (Bp((CF3)2))RuI((BuNH2)-Bu-t)(2) (9a) is isolated and characterized by an X-ray structural determination. The analogous chloro c omplex (Bp((CF3)2))RuCl((BuNH2)-Bu-t)(2) (10a) can be prepared by stirring a dichloromethane solution of 8a for 18 h. In the absence of dihydrogen, 1a reacts with a large excess of (BuNH2)-Bu-t to give (Bp((CF3)2))RuH(COD)((B uNH2)-Bu-t) (11a). The structure with a kappa(2) N,H coordination of the Bp ((CF3)2) ligand is confirmed by an X-ray determination. Using the more ster ically demanding diisopropylamine in the same conditions used for the forma tion of 8a, we could not isolate any complex. However upon N-2 atmosphere, the dinuclear species with a mu(2)-bridging dinitrogen ligand [(Bp((CF3)2)) RuH((Pr2NH)-Pr-i)](2)(N-2) (12a) could be isolated and characterized by a s ingle-crystal X-ray determination. Addition of mesitylene to 1a produces th e arene complex ((Bp((CF3)2))RuH(eta(6)H(3)Me(3)) (13a). The X-ray structur e determination gave conclusive evidence for the kappa(2) N,N bonding mode of the Bp((CF3)2) ligand. When exposing la to a CO atmosphere, the new acyl (dicarbonyl) complex (Bp((CF3)2))Ru(COC8H13)(CO)(2) (14a) is isolated in ve ry high yield. Its structure is fully characterized on the basis of 2D homo nuclear and heteronuclear correlation NMR data and by an X-ray structural d etermination. Similar reactions have been performed using the nonfluorinate d complex (Bp(Me2))RuH(COD) (1b) as starting material. The analogous comple xes 2b, 4b-6b, and 14b have been obtained. The variation of of the hapticit y of the Bp ligand plays a crucial role in this chemistry, but the fluorina ted substituents have a limited influence.