1,3-Bis(2,6-diisopropyl­phen­yl)imidazolidinium tetra­phenyl­borate dichloro­methane disolvate

The title compound, C27H39N2 +·C24H20B−·2CH2Cl2, is the first reported imidazolidinium cation with the sterically demanding 2,6-diisopropyl­phenyl groups in the 1,3-positions. The crystal structure is stabilized by weak inter­molecular C—H⋯π(arene) inter­actions. Due to the bulky nature of both the flanking 2,6-diisopropyl­phenyl substituents and the tetra­phenyl­borate counter-ion, anion inter­actions with the imidazolidinium H atom in the 2-position are not observed, also a first for this class of ortho-alkyl-substituted Arduengo-type carbene precursors

1,3-Bis(2,6-diisopropyl­phen­yl)imidazolidin-2-yl­idene

The title compound, C27H38N2, is the first reported free imidazolidin-2-yl­idene carbene with 2,6-diisopropyl­phenyl groups in the 1,3-positions. The five-membered ring adopts a twisted conformation and the dihedral angle between the aromatic rings is 48.81 (6)°. Both isopropyl groups attached to one of the benzene rings are disordered over two sets of sites in 0.74 (2):0.26 (2) and 0.599 (8):0.401 (8) ratios

Hexaaqua­gallium(III) trinitrate trihydrate

The title compound, [Ga(H2O)6](NO3)3·3H2O, is isostructural to other known M III nitrate hydrates (M = Al, Cr, Fe). The structure contains two distinct octa­hedral Ga(OH2)6 units (each of symmetry) which are involved in inter­molecular hydrogen bonding with the three nitrate anions and three water mol­ecules within the asymmetric unit

Crystal structure of 2-chloro-1,3-bis(2,6-diiso- propylphenyl)-1,3,2-diazaphospholidine 2-oxide

Published versionThe title compound, C26H38ClN2OP, was synthesized by reacting phosphoryl chloride with N,N′-bis­(2,6-diiso­propyl­phen­yl)ethane-1,2-di­amine in the presence of N-methyl­morpholine which acted as an auxilliary base to quench the HCl released as a by-product. The resultant N-heterocyclic phosphine five-membered ring adopts a half-chair conformation and features a tetra­coordinate P atom ligated by the chelating di­amine [P—N = 1.6348 (14) and 1.6192 (14) Å], one double-bonded O atom [P1—O1 = 1.4652 (12) Å] and one Cl atom [P1—Cl1 = 2.0592 (7) Å]. The sterically hindered 2,6-diiso­propyl­phenyl (Dipp) groups twist away from the central heterocycle, with torsion angles of −75.66 (19) and 83.39 (19)° for the P—N—Car—Car links. A number of intra­molecular C—H...N, C—H...O and C—H...Cl close contacts occur. In the crystal, mol­ecules are linked by C—H...O hydrogen bonds to generate [010] chains. C—H...Π inter­actions are also observed

(η5-Cyclo­penta­dien­yl)[(1,2,3,4,4a,12a-η)-naphtho­[2,3-b][1,4]benzodioxine]iron(II) hexa­fluoridophosphate

At 296 (2) K, both complexed rings in the iron(II) complex cation of the title salt, [Fe(C5H5)(C16H10O2)]PF6, are almost parallel [dihedral angle between planes = 2.4 (3)°]. The quaternary C atoms of the complexed arene ring are located at the longest distance from the Fe atom, with Fe—C distances of 2.112 (4) and 2.105 (3) Å, which are slightly longer than the average Fe—C distance for this ring (2.083 Å). The Fe ion is located 1.660 (1) and 1.543 (1) Å, respectively, from the cyclo­penta­dienyl and the complexed arene ring

A new polymorph of 2,6-bis(trifluoromethyl)benzoic acid

Publisher's version/PDFThe asymmetric unit of a second polymorph of the title compound, C[subscript 9]H[subscript 4]F[subscript 6]O[subscript 2], contains five independent molecules, which form hydrogen-bonded O—H[ellipsis]O dimers about inversion centers. The most significant structural difference between this structure and that of the first polymorph [Tobin & Masuda (2009). Acta Cryst. E65, o1217] is the hydrogen-bonded, dimeric orientation of the carboxylic acid functionalities

The crystal structures of two isomers of 5-(phenyl- isothiazolyl)-1,3,4-oxathiazol-2-one

Published VersionThe syntheses and crystal structures of two isomers of phenyl iso­thia­zolyl oxa­thia­zolone, C11H6N2O2S2, are described [systematic names: 5-(3-phenyl­iso­thia­zol-5-yl)-1,3,4-oxa­thia­zol-2-one, (I), and 5-(3-phenyl­iso­thia­zol-4-yl)-1,3,4-oxa­thia­zol-2-one, (II)]. There are two almost planar (r.m.s. deviations = 0.032 and 0.063 Å) mol­ecules of isomer (I) in the asymmetric unit, which form centrosymmetric tetra­mers linked by strong S...N [3.072 (2) Å] and S...O contacts [3.089 (1) Å]. The tetra­mers are π-stacked parallel to the a-axis direction. The single mol­ecule in the asymmetric unit of isomer (II) is twisted into a non-planar conformation by steric repulsion [dihedral angles between the central iso­thia­zolyl ring and the pendant oxa­thia­zolone and phenyl rings are 13.27 (6) and 61.18 (7)°, respectively], which disrupts the π-conjugation between the heteroaromatic iso­thia­zoloyl ring and the non-aromatic oxa­thia­zolone heterocycle. In the crystal of isomer (II), the strong S...O [3.020 (1) Å] and S...C contacts [3.299 (2) Å] and the non-planar structure of the mol­ecule lead to a form of π-stacking not observed in isomer (I) or other oxathiazolone derivatives

1-(2,4,6-Triisopropyl­phen­yl)ethanone

The title compound, C17H26O, is a di-ortho-alkyl substituted phenyl ethanone that exhibits a significant twisting of the ketone fragment relative to the aromatic ring [O—C—C—C torsion angle = 89.32 (17)°] due to steric pressure from the ortho-isopropyl groups. One ortho- and the para-isopropyl group exhibit orientational disorder with a refined site occupancy factor of 0.562 (3):0.438 (3)

Crystal structure determination as part of an ongoing undergraduate organic laboratory project: 5-[(<i>E</i>)-styryl]-1,3,4-oxathiazol-2-one

Published versionThe title compound, C10H7NO2S, provides the first structure of an &alpha;-alkenyl oxathiazolone ring. The phenyl ring and the oxa&shy;thia&shy;zolone groups make dihedral angles of 0.3 (3) and &minus;2.8 (3)&deg;, respectively, with the plane of the central alkene group; the dihedral angle between the rings is 2.68 (8)&deg;. A careful consideration of bond lengths provides insight into the electronic structure and reactivity of the title compound. In the crystal, extended &Pi;-stacking is observed parallel to the a-axis direction, consisting of cofacial head-to-tail dimeric units [centroid&ndash;centroid distance of 3.6191 (11) &Aring;]. These dimeric units are separated by a slightly longer centroid&ndash;centroid distance of 3.8383 (12) &Aring;, generating infinite stacks of mol&shy;ecules

Anhydrous TEMPO-H: reactions of a good hydrogen atom donor with low-valent carbon centres

Publisher's version/PDFIn this paper, we report a novel synthesis of anhydrous 1-hydroxy-2,2,6,6-tetramethyl-piperidine (TEMPO-H). An X-ray crystal structure and full characterization of the compound are included. Compared to hydrated TEMPO-H, its anhydrous form exhibits improved stability and a differing chemical reactivity. The reactions of anhydrous TEMPO-H with a variety of low-valent carbon centres are described. For example, anhydrous TEMPO-H was reacted with 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene (IMes), an unsaturated NHC. Crystals of CHNC[subscript 6H[subscript 2](CH[subscript 3])[subscript 3]][subscript 2]C...HO-(NC[subscript 5]H[subscript 6](CH[subscript 3])[subscript 4]), IMes...TEMPO-H, were isolated and a crystal structure determined. The experimental structure is compared to the results of theoretical calculations on the hydrogen-bonded dimer. Anhydrous TEMPO-H was also reacted with the saturated NHC, 1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene (SIPr), giving the product [CH[subscript 2]Ni-Pr[subscript 2]C[subscript 6]H[subscript 3]][subscript 2]CH...O(NC[subscript 5]H[subscript 6](CH[subscript 3])[subscript 4]). In contrast, the reaction of hydrated TEMPO-H with 1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene gave small amounts of the hydrolysis product, N-(2,6-diisopropylphenyl)-N-[2-(2,6-diisopropylphenylamino)ethyl]formamide. Finally, anhydrous TEMPO-H was reacted with (triphenylphosphoranylidene)ketene to generate Ph[subscript 3]PC(H)C(=O)O(NC[subscript 5]H[subscript 6](CH[subscript 3])[subscript 4]). A full characterization of the product, including an X-ray crystal structure, is described