UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Reactivity and coordination chemistry of ruthenium(II) aminophosphine complexes with H2S,thiols,H2O and other small molecules Ma, Erin Shu Fen

Abstract

The coordination of small molecules (H₂S, RSH, H₂0, ROH, H₂ , NH₃ , N₂ and N₂0; R = alkyl) to the coordinatively unsaturated complexes RuX₂ (P-N)(PR₃) (X = CL Br, I; P-N = [o-(7Y,A/-dimethylamino)phenyl]diphenylphosphine; R = Ph, /7-tolyl), themselves prepared from RuX₂ (PR₃)₃ and P-N, was investigated (see figure). The species containing the Ru(P-N) moiety were characterized spectroscopically, particularly by *H and 31P{1H} NMR and in some cases in conjunction with X-ray crystallography. [picture of chemical structues] Cis-RuX₂ (P-N)(PPh₃)(L) species (X = CI, L = H₂S, MeSH, EtSH; X = Br, L = H₂S) were isolated from the reaction of RuX₂ (P-N)(PPh₃) with excess L in acetone, and characterized crystallographically. The geometry of these complexes is pseudo-octahedral with the halogen atoms in mutual cis positions with the coordinated S-ligand cis to the P-atom of the P-N ligand and trans to a halogen atom; all H-atoms on the coordinated S-ligands were refined isotropically. The S-H bond lengths are of equal or shorter distances (1.20 - 1.34 Å) than those of free gaseous ligands (1.33 - 1.40 Å); in particular, the bond length of 1.03 Å for the coordinated MeSH complex is the shortest S-H distance yet reported. Of interest, the ^NMR spectrum of c/s-RuX₂ (P-N)(PPh₃)(SH₂) shows three-bond coupling of only one proton of the coordinated H₂S to the P-atom of the P-N ligand (X = C1, 3JHP= 3.5 HZ; X = Br, 3JHP = 4.3 Hz) at -50°C, and this represents an extension of the Karplus relationship to vicinal coupling within a P-Ru-S-H system. The reaction of RuCl₂ (P-N)(PR₃) with H20 gave /raws-RuCl₂ (P-N)(PR3XOH₂), which was crystallographically characterized. The geometry is pseudo-octahedral with mutually trans Cl-atoms; the H₂0 ligand is trans to the P-atom of the P-N ligand. The orientation of incoming monodentate ligand L in either cis or trans positions (see figure) is affected by the mutual trans influence of L and of the apical phosphine of RuX₂ (P-N)(PR₃). The thermodynamics for the reversible binding of H2S, thiols, H 2 and H20 to RuCl₂ (P-N)(PPh₃), in solution, were determined using UV-Vis and NMR spectroscopies. The low AH0 values (-22 to -54 kJ/mol) imply relatively weak Ru-L bond energies and the negative AS° values (-32 to -140 J/mol K) are consistent with binding of a small molecule at a metal site. Differential scanning calorimetry on solid state samples also allowed for determination of AH° values, and estimation of enthalpy changes for a cis- to transrearrangement in solution. Cw-RuX₂ (P-N)(PPh3)(SH₂) (X = CI, Br) reacted with NaSH or proton sponge (in the presence of added H2S) to give initially Ru(SH)Cl(P-N)(PPh3) and then Ru(SH)₂ (P-N)(PPh₃). The mercapto species, however, are thermally unstable and were only observed by NMR spectroscopy at -78°C. Reaction of 1 atm NH3 with RuX₂ (P-N)(PPh₃) (X = CI, Br) in the solid state led to the formation of frans-RuX₂ (P-N)(PPh3)(NH₃) which, when dissolved in solution, subsequently isomerized to cw-RuX₂ (P-N)(PPh3)(NH₃). Evidence for bis- and tris-arnmine species, as well as for [RuX(P-N)(PPh₃)(NH₃) ₂—X] with a 'strongly associated' halide, is also presented. The formation of cis-RuCl₂ (P-]S0(PPh₃)(N₂O) was observed by NMR spectroscopy at -40°C when RuCl₂ (P-N)(PPh₃) was subjected to 6 atm N₂0 in CD₂Cl₂. The coordination of N₂0 is of particular interest because of the rarity of such a reaction and because of the potential of discovering an effective catalytic oxidation system using N₂0 as an O-atom donor. In fact, c/5-RuCl₂ (P-N)(PPh₃)(N₂0) appears to form c/s-RuCl₂ (P-]S0(PPh₃)(V-N₂) and 02 at T > -40°C. When the system was warmed to room temperature, 0=PPh₃ and (u,-0)(n-Cl)₂[RuCl(P-N)]₂ were formed. The crystallographically characterized u>oxo complex was also formed when RuCl₂(P-N)(PPh₃) was reacted with 0₂. RuCl₂(P-N)(PPh₃) also reacted with HOCPh to give the crystallographically characterized cw-RuCl₂{TJ-N)(PPh₃)(=C=CHPh). The carbene complex reacted with H2S and H₂0 to give c/j-RuCl₂(P-N)(PPh₃)(S=C(H)CH₂Ph) and a mixture containing RuCl(P-N)(PPh₃)(CH₂Ph)(CO) and RuCl₂(P-N)(PPh₃)(CO), respectively. The formulations of the products were based on 31P{1H} NMR and IR spectroscopic data. The reactions of RuCl₂(PR₃) ₃ with aminophosphine ligands other than P-N were also explored: RuCl₂(BPN)(PR₃) (BPN = bis[o-N,N-dimethylammo)phenyl]phenylphosphine) and RuCl₂(PAN)(PR₃) (PAN = l-(N,N-dimethylamino)-8-(diphenylphosphino)naphthalene) were isolated and characterized; RuCl₂(AMPHOS)(PPh₃) (AMPHOS = (R)-(+)-N,N-dimethyl-l-[o- (dimethylphosphino)phenyl]ethylamine) was observed in situ, and an impure sample of RuCl₂(ALAPHOS)₂ (ALAPHOS = [(S)-2-(dimethylamino)propyl]diphenylphosphine) was isolated. PTN (tris[o-(N,N-dimethylamino)phenyl]phenylphosphine) did not react with RuCl₂(PR₃)₃.

Item Media

Item Citations and Data

Rights

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

Usage Statistics