Ruthenium hydrides containing the superhindered polydentate polyphosphine ligand P(CH2CH2P(t)Bu2)3.

The complex RuH2(N2)(P(2)P3(tBu)) (1) containing the extremely bulky PP3-type ligand P(2)P3(tBu) = P(CH2CH2P(t)Bu2)3 was synthesized by reduction of RuCl2(P(2)P3(tBu)) (2) with Na/NH3 under a N2 atmosphere. Like other complexes containing the P(2)P3(tBu) ligand, only three of the four donor phosphines are coordinated, and one of the phosphines remains as a dangling pendant phosphine. Reduction of RuCl2(P(2)P3(tBu)) (2) with a range of the more usual hydride reducing agents afforded the previously unknown ruthenium hydride complexes RuHCl(P(2)P3(tBu)) (3), RuH(BH4)(P(2)P3(tBu)) (6), RuH(AlH4)(P(2)P3(tBu)) (7), and the ruthenium(II) trihydride K[Ru(H)3(P(2)P3(tBu))] (8). The ruthenium tetrahydride containing a coordinated H2 ligand RuH2(H2)(P(2)P3(tBu)) (10) was synthesized by exchange of N2 in 1 by H2. Complexes 1, 3, 6, 7, and 8 were characterized by crystallography and multinuclear NMR spectroscopy.