ABSTRACT
Spontaneous ion separation of the scorpionate beryllium complex, TpBeI 1 (Tp = 1-trispyrazolylborate), occurs upon treatment with THF, yielding [TpBe(thf)]I 2, which was characterized by heteronuclear NMR spectroscopy (1H, 9Be, 13C) and structurally characterized by single crystal X-ray diffraction. 2 represents a rare example of a structurally characterized monocationic beryllium complex, and to the best of our knowledge, the synthesis of 2 by a solvent-induced ion separation has previously only been observed in the reactions of beryllium dihalides with strong Lewis bases.
ABSTRACT
[Ph4 P]2 [Be(N3 )4 ] (1) and [PNP]2 [Be(N3 )4 ] (2; PNP=Ph3 PNPPh3 ) were synthesized by reacting Be(N3 )2 with [Ph4 P]N3 and [PNP]N3 . Compound 1 represents the first structurally characterized homoleptic beryllium azide. The electronic structure and bonding situation in the tetraazidoberyllate dianion [Be(N3 )4 ]2- were investigated by quantum-chemical calculations (NPA, ELF, LOL).
ABSTRACT
RGa {R=HC[C(Me)N(2,6-iPr2C6H3)]2} reacts with Sb(NMe2)3 with insertion into the Sb-N bond and elimination of RGa(NMe2)2 (2), yielding the Ga-substituted distibene R(Me2N)GaSb=SbGa(NMe2 )R (1). Thermolysis of 1 proceeded with elimination of RGa and 2 and subsequent formation of the bicyclo[1.1.0]butane analogue [R(Me2N)Ga]2Sb4 (3).
ABSTRACT
LGa (L = [(2,6-i-Pr2-C6H3)NC(Me)]2CH) reacts with elemental tellurium with formation of the Te-bridged compound [LGa-µ-Te]2 1, whereas the reactions with Ph2Te2 and i-Pr2Te occurred with cleavage of the Te-Te and Te-C bond, respectively, and subsequent formation of LGa(TePh)2 2 and LGa(i-Pr)Tei-Pr 3. 1-3 were characterized by heteronuclear NMR ((1)H, (13)C, (125)Te) and IR spectroscopy and their solid state structures were determined by single crystal X-ray analyses.
ABSTRACT
Monovalent RAl (R=HC[C(Me)N(2,6-iPr2C6H3)]2) reacts with E2Et4 (E=Sb, Bi) with insertion into the weak E-E bond and subsequent formation of RAl(EEt2)2 (E=Sb 1; Bi 2). The analogous reactions of RGa with E2Et4 yield a temperature-dependent equilibrium between RGa(EEt2)2 (E=Sb 3; Bi 4) and the starting reagents. RIn does not interact with Sb2Et4 under various reaction conditions, but formation of RIn(BiEt2)2 (5) was observed in the reaction with Bi2Et4 at low temperature.
ABSTRACT
Triethylchalcogenostiboranes Et3Sb[double bond, length as m-dash]E (E = S , Se ) were synthesized and their solid state structures were determined. The Sb-Se bond length is the shortest ever reported. Short SbE contacts were not observed. According to quantum chemical calculations, the bonding situation in and is best described as a polarized Sb-E single bond.
ABSTRACT
The synthesis and crystal structures of 1-tris(pyrazolyl)borate beryllium halides TpBeX (X = Cl 1, Br 2, I 3, F 4), the pyrazole adduct of TpBeF (5) and of 1-tris(pyrazolyl)borate beryllium hydride, deuteride and azide TpBeX (X = H 6, (2)H (D) 7, N3 8; Tp = 1-trispyrazolylborate) is described. In addition, (9)Be-NMR spectroscopy is introduced as suitable analytical tool for the in situ characterization of heteroleptic organoberyllium halides, pseudohalides and hydrides. Studies in different solvents and solvent mixtures allowed the formulation of a reference guide for the chemical shift of heteroleptic coordination complexes of beryllium only based on variation of the second substituent.
ABSTRACT
Methanetrisamidines {HC[C(NR)NHR]3} (R = i-Pr 1a; Ph 1b) were reacted with different metal complexes. Reaction of 1a with NiCl2(H2O)6 occurred with protonation of 1a and formation of {[C(C(NHi-Pr)2)3](2+)[NiCl4](2-)} 2, whereas the reaction with CuCl gave [C(C(N(i-Pr)CuCl)NHi-Pr)2(C(NHi-Pr)2)] 3. The formation of 2 and 3, which contain the N-H tautomeric form of 1a, occurred with H-migration from carbon to nitrogen. In contrast, reactions of 1b with [M(NCMe)3(CO)3] (M = Cr, Mo, W) yielded octahedral complexes fac-[M(CO)3CH(C(NHPh)NPh)3] (M = Cr 4a, Mo 4b, W 4c), in which the C-H tautomeric form is preserved. 1b is a rather strong σ-donor ligand as was shown by IR spectroscopy. The structures of 2, 3 and 4a were determined by single crystal X-ray diffraction.
ABSTRACT
By embedding an azobenzene unit into a chiral scaffold, switching of azobenzene from the trans-(P) isomer to the cis-(P) isomer and back was achieved (black arrows in picture). The embedding leads to a flipping process in which the phenyl rings can only move directly towards one another in the switching process.
Subject(s)
Azo Compounds/chemistry , Peptides, Cyclic/chemistry , Magnetic Resonance Spectroscopy , Models, Chemical , Molecular Structure , StereoisomerismABSTRACT
Coordination of a strong σ-base has been shown to be an effective method for the stabilization of low valent main group element complexes. This general method was now used for the synthesis of the divalent germanium diazide. IPrGe(N3)21 represents the first neutral homoleptic germanium diazide that could be structurally characterized.
ABSTRACT
Two neutral group 15-pentaazides dmap-As(N(3))(5) (1) and dmap-Sb(N(3))(5) (2) were synthesized and structurally characterized for the first time (dmap = 4-dimethylaminopyridine). Base-stabilization was confirmed to be very suitable for the kinetic stabilization of highly explosive covalent main group polyazides.
ABSTRACT
In situ cryocrystallization has been employed to grow single crystals of 4-methoxybenzaldehyde (anisaldehyde), C(8)H(8)O(2), 2-hydroxybenzaldehyde (salicylaldehyde), C(7)H(6)O(2), and (2E)-3-phenylprop-2-enal (cinnamaldehyde), C(9)H(8)O, all of which are liquids at room temperature. Several weak C-H···O interactions of the types C(aryl)-H···O, C(formyl)-H···O and Csp(3)-H···O are present in these related crystal structures.
ABSTRACT
Directional Cl···Cl type I and II interactions govern the low-density aggregation of 1,1,2,2-tetrachloroethane molecules in synclinal conformation in the crystalline state at low temperature, whereas the dense molecular packing in high-pressure is achieved for the antiperiplanar conformers and electrostatically less favored Cl···Cl contacts. The mechanism of transformation between loose and dense associations involves the collapse of Cl···Cl contacts and conformational conversion.
Subject(s)
Ethane/analogs & derivatives , Hydrocarbons, Chlorinated/chemistry , Chlorides/chemistry , Crystallography, X-Ray , Ethane/chemistry , Molecular Conformation , Pressure , TemperatureABSTRACT
Structural and electronic properties of C-H···O contacts in compounds containing a formyl group are investigated from the perspective of both hydrogen bonding and dipole-dipole interactions, in a systematic and graded approach. The effects of α-substitution and self-association on the nature of the formyl H-atom are studied with the NBO and AIM methodologies. The relative dipole-dipole contributions in formyl C-H···O interactions are obtained for aldehyde dimers. The stabilities and energies of aldehyde clusters (dimer through octamer) have been examined computationally. Such studies have an implication in crystallization mechanisms. Experimental X-ray crystal structures of formaldehyde, acrolein and N-methylformamide have been determined in order to ascertain the role of C-H···O interactions in the crystal packing of formyl compounds.
ABSTRACT
Antimony(III) complexes of the general type LSbF(2) (3: L(1) =[tBuC(NiPr)(2)]; 4: L(2) =[tBuC(NDipp)(2) , Dipp=2,6-iPr(2)C(6)H(3)) and LSb(N(3))(2) (6: L(1); 7: L(2)) were prepared in high yields and characterized by elemental analyses, NMR and IR spectroscopy and single-crystal X-ray diffraction. Moreover, the solid-state structures of [L(2)SbF(2)][L(2)Li] (5), [L(2) AlH(2)] (1), and [L'H][L'K(thf)(3)] (2; L'=HC(NDipp)(2)) are described, in which the Li (5) and K atoms (2) adopt rather unusual coordination modes.
ABSTRACT
Synthesis of group 15-triazides E(N(3))(3) (E = Sb 1, Bi 2) and Py(2)-Bi(N(3))(3)3 (Py = pyridine). Single crystals of 1 were in situ grown by an IR-laser-assisted technique on the diffractometer. The structure of 3, which represents the first structurally characterized neutral Bi-triazide, is influenced by crystal packing effects according to DFT calculations.