119567-05-4Relevant articles and documents
The facile transformation of a hydrido alkynyl to vinylidene ligand on a tetranuclear metal framework, a process involving a reversible skeletal rearrangement. Syntheses and crystal structures of the triruthenium-platinum clusters Ru3Pt(μ-H){μ4-η 2-C≡C(t-Bu)}(CO)9(C8H12), Ru ...
Ewing, Paul,Farrugia, Louis J.
, p. 1246 - 1260 (2008/10/08)
Full title: The facile transformation of a hydrido alkynyl to vinylidene ligand on a tetranuclear metal framework, a process involving a reversible skeletal rearrangement. Syntheses and crystal structures of the triruthenium-platinum clusters Ru3Pt(μ-H){μ4-η 2-C≡C(t-Bu)}(CO)9(C8H12), Ru3Pt(μ-H){μ4-η 2-C≡C(t-Bu)}(CO)9(Ph2P(CH 2)2PPh2), Ru3Pt(μ4-η2-C=C(H)t-Bu)(CO) 9(Ph2P(CH2)2PPh2), and [Ru3Pt(μ-H)(μ4-η 2-C=C(H)t-Bu)(CO)9(Ph2P(CH2) 2PPh2)]+BF4-. Treatment of R3(μ-H){μ3-η 2-C≡C(t-Bu)}(CO)9 with Pt(COD)2 (COD = cycloocta-1,5-diene) affords the tetranuclear alkynyl cluster Ru3Pt(μ-H){μ4-η 2-C≡C(t-Bu)}(CO)9(COD) (4). Crystal data for 4: monoclinic, space group P21/n; a = 11.283 (3), b = 17.843 (2), c = 13.625 (3) A°; β= 94.06 (2)°; V = 2736 (1) A?3; Z = 4; final R (Rw) values 0.023 (0.029) for 3815 independent observed data (I > 3.0σ(I)). 4 has an "out-of-plane" spiked-triangular metal framework with a platinum atom bonded to an equilateral Ru3 triangle via one Ru atom (Ru-Ru = 2.791 (1)-2.815 (1), Ru(2)-Pt = 2.645 (1) A?). The μ4-η2(⊥)-alkynyl ligand is σ-bonded to the Pt atom and Ru(2) and asymmetrically π-bonded to the remaining two Ru atoms (Ru(1)-C(11) = 2.484 (5), Ru(3)-C(11) = 2.291 (5) A?), which are also bridged by a hydride. The Pt atom is asymmetrically chelated to a COD ligand, which is easily displaced by bis(diphenylphosphino)ethane (dppe) affording two complexes, the hydrido alkynyl Ru3Pt(μ-H){μ4-η 2-C≡C(t-Bu)}(CO)9(dppe) (6) and the tautomeric vinylidene cluster Ru3Pt(μ4-η2-C=C(H)t-Bu)(CO) 9(dppe) (11). Crystal data for 6: monoclinic, space group P21/n; a = 13.867 (3), b = 17.725 (2), c = 17.429 (7) A?; β= 92.50 (2)°; V = 4280 (2) A?3; Z = 4; final R (Rw) values 0.028 (0.032) for 5167 independent observed data (I > 3.0σ(I)). Crystal data for 11: monoclinic, space group C2/c; a = 47.561 (5), b = 12.176 (2), c = 23.155 (10) A?; β= 118.27 (2)°; V = 11810 (6) A?3; Z = 8; final R (Rw) values 0.048 (0.056) for 5865 independent observed data (I > 2.5σ(I)). Complex 6 has a similar Ru3Pt core (Ru-Ru = 2.792 (1)-2.824 (1), Ru(3)-Pt = 2.681 (1) A?) and μ4-η2 (⊥)-alkynyl geometry to that found in 4, except that this ligand is more symmetrically π-bonded to the two hydrido-bridged Ru atoms (Ru(1)-C(11) = 2.396 (6), Ru(2)-C(11) = 2.427 (6) A?). Complex 11 has a μ4-η2-vinylidene ligand bonded to a butterfly Ru3Pt core, with the Pt atom on a wingtip (Ru-Ru = 2.708 (2)-2.823 (2) A?; Pt-Ru = 2.730 (1), 2.792 (1) A?). The vinylidene moiety is σ-bonded to the Pt atom and to two Ru atoms and is π-bonded to the remaining Ru center. Complexes 6 and 11 readily interconvert in solution, with 11 being the thermodynamically favored product. This facile process involves a reversible skeletal rearrangement of the Ru3Pt core, and kinetic studies imply an intramolecular mechanism. 11 is protonated by HBF4 along a metal-metal edge, giving the cationic hydrido vinylidene cluster [Ru3Pt(μ-H)(μ4-η 2-C=C(H)t-Bu)-(CO)9(dppe)]+BF4 - (17). Crystal data for 17: triclinic, space group P1; a = 10.189 (4), b = 14.329 (4), c = 15.596 (9) A?; α = 97.70 (4), β= 94.72 (4), γ= 98.75 (3)°; V = 2218 (2) A?3; Z = 2, final R (Rw) values 0.035 (0.044) for 6293 independent observed data (I > 3.0σ(I)). The cluster core closely resembles that found in 11, with a hydride ligand bridging the hinge Ru-Ru vector. Protonation of 6 occurs at the α-carbon of the acetylide affording the alkyne complex [Ru3Pt(μ-H)(μ4-η 2-HC≡C(t-Bu))(CO)9(dppe)]+BF 4- (18). 18 irreversibly isomerizes to 17 in solution.
