3404-63-5Relevant articles and documents
A Series of Crystallographically Characterized Linear and Branched σ-Alkane Complexes of Rhodium: From Propane to 3-Methylpentane
Bukvic, Alexander J.,Burnage, Arron L.,Tizzard, Graham J.,Martínez-Martínez, Antonio J.,Mckay, Alasdair I.,Rees, Nicholas H.,Tegner, Bengt E.,Kr?mer, Tobias,Fish, Heather,Warren, Mark R.,Coles, Simon J.,Macgregor, Stuart A.,Weller, Andrew S.
supporting information, p. 5106 - 5120 (2021/05/04)
Using solid-state molecular organometallic (SMOM) techniques, in particular solid/gas single-crystal to single-crystal reactivity, a series of σ-alkane complexes of the general formula [Rh(Cy2PCH2CH2PCy2)(ηn:ηm-alkane)][BArF4] have been prepared (alkane = propane, 2-methylbutane, hexane, 3-methylpentane; ArF = 3,5-(CF3)2C6H3). These new complexes have been characterized using single crystal X-ray diffraction, solid-state NMR spectroscopy and DFT computational techniques and present a variety of Rh(I)···H-C binding motifs at the metal coordination site: 1,2-η2:η2 (2-methylbutane), 1,3-η2:η2 (propane), 2,4-η2:η2 (hexane), and 1,4-η1:η2 (3-methylpentane). For the linear alkanes propane and hexane, some additional Rh(I)···H-C interactions with the geminal C-H bonds are also evident. The stability of these complexes with respect to alkane loss in the solid state varies with the identity of the alkane: from propane that decomposes rapidly at 295 K to 2-methylbutane that is stable and instead undergoes an acceptorless dehydrogenation to form a bound alkene complex. In each case the alkane sits in a binding pocket defined by the {Rh(Cy2PCH2CH2PCy2)}+ fragment and the surrounding array of [BArF4]- anions. For the propane complex, a small alkane binding energy, driven in part by a lack of stabilizing short contacts with the surrounding anions, correlates with the fleeting stability of this species. 2-Methylbutane forms more short contacts within the binding pocket, and as a result the complex is considerably more stable. However, the complex of the larger 3-methylpentane ligand shows lower stability. Empirically, there therefore appears to be an optimal fit between the size and shape of the alkane and overall stability. Such observations are related to guest/host interactions in solution supramolecular chemistry and the holistic role of 1°, 2°, and 3° environments in metalloenzymes.
Synthesis, Structure, and Reactions of Stable Titanacyclopentanes
Mashima, Kazushi,Sakai, Nozomu,Takaya, Hidemasa
, p. 2475 - 2483 (2007/10/02)
Titanacyclic compounds of the formula Cp*2Ti(CH2CH2C(CH2CHR)CH2) (5a; R=H and 5b; R=C6H5, Cp*=pentamethylcyclopentadienyl), the first stable titanacyclopentanes, have been prepared by the reaction of bis(pentamethylcyclopentadienyl)titanium-ethylene complex (3) with methylenecyclopropanes (4), and their structures were determined based on both spectroscopic data and X-ray crystallography.Complex 5b crystallized in space group P21/a (Z=4) with cell constants, a=21.832(3), b=8.580(1), c=14.759(2) Angstroem, β=96.81(1) deg, U=2744.9(6) Angstroem3 (4261 reflections, R=0.053).The reaction of 5 with carbon monoxide afforded spiroheptan-5-ones in 98percent yield.The thermal decomposition of 5 has been investigated, and possible mechanisms of the reactions have been proposed based on deuterium-labeled experiments.A novel formal reductive elimination of organic ligands giving 1-phenylspirohexane has been observed in the thermolysis of 5b.A structure-reactivity relationship has been discussed.
