114249-89-7Relevant academic research and scientific papers
Activation of an aliphatic C-H bond at room temperature. Conversion on a cluster of a stable σ-bonded alkyl group to a μ2-alkylidene ligand. Synthesis and crystal structure determination of HOs3(6-CH2C5H 3N-2-C(H)=N-i-Pr)(CO)9 and H2Os3(6-CHC5H3 ...
Zoet, Robert,Van Koten, Gerard,Vrieze, Kees,Jansen, Jacob,Goubitz, Kees,Stam, Casper H.
, p. 1565 - 1572 (2008/10/08)
Full title: Activation of an aliphatic C-H bond at room temperature. Conversion on a cluster of a stable σ-bonded alkyl group to a μ2-alkylidene ligand. Synthesis and crystal structure determination of HOs3(6-CH2C5H 3N-2-C(H)=N-i-Pr)(CO)9 and H2Os3(6-CHC5H3N-2-C(H)=N-i-Pr) (CO)81,2. Os3(CO)10(MeCN)2 reacts with i-Pr-Pyca{Me}2 in toluene at room temperature to give HOs3(6-CH2C5H 3N-2-C(H)=N-i-Pr)(CO)9 (1), one of the few examples of a cluster with a metal-σ-alkyl bond. The presence of the latter type of bond was demonstrated by a single-crystal X-ray structure determination. Crystals of HOs3(6-CH2C5H 3N-2-C(H)=N-i-Pr)(CO)9 (1) are monoclinic of space group P21/a with cell constants a = 16.480 (3) A?, b = 14.805 (2) A?, c = 9.459 (1) A?, β = 94.74 (2)°, and Z = 4. A total of 3267 reflections have been used in the refinement, resulting in a final R value of 0.057. Complex 1 is a coordinatively saturated 48e cluster containing a triangular array of osmium atoms [Os(1)-Os(2) = 2.885 (1) A?, Os(2)-Os(3) = 2.971 (1) A?, and Os(1)-Os(3) = 2.905 (1) A?]. The i-Pr-Pyca{Me} ligand has been converted into a monoanionic tridentate ligand that is bonded in a σ,σ-N,N′-chelate (4e) fashion to Os(2) and via a single σ-C-Os interaction [Os(3)-C(6) = 2.22 (2) A?] to the Os3(CO)9 unit. The most interesting part of the structure is the σ-bonded alkyl moiety that has been formed by C-H activation of the 6-Me substituent on the pyridine and is stabilized by the chelate-bonded α-diimine moiety. The hydride was not located, but from structural features it can be deduced to bridge the Os(2)-Os(3) bond. On thermolysis of 1 in n-nonane at 130°C CO was eliminated and H2Os3(6-CHC5H 3N-2-C(H)=N-i-Pr)(CO)8 (2) was formed. Crystals of H2Os3(6-CHC5H 3N-2-C(H)=N-i-Pr)(CO)8 (2) are monoclinic of space group P21/n with cell constants a = 16.284 (1) A?, b = 16.325 (1) A?, c = 8.605 (1) A?, β = 93.80 (1)°, and Z = 4. A total of 3174 reflections have been used in the refinement, resulting in a final R value of 0.051. The X-ray structure determination showed that the σ-bonded alkyl moiety in 1 is converted to an alkylidene ligand which is almost symmetrically bridging an Os-Os bond [Os(1)-C(6) = 2.14 (1) A? and Os(3)-C(6) = 2.18 (1) A?], leaving the geometry of the chelate-bonded α-diimine moiety virtually unchanged. The molecule contains three Os-Os bonds [Os(1)-Os(2) = 2.785 (1) A?, Os(2)-Os(3) = 2.806 (1) A?, and Os(1)-Os(3) = 2.981 (2) A?]. The two hydrides were not located, but structural features indicate that they are bridging the Os(1)-Os(3) and Os(2)-Os(3) bonds.
