Complexation of Constrained Ligands Piperazine, N-substituted Piperazines, and Thiomorpholine

2009 ◽  
Vol 62 (10) ◽  
pp. 1196 ◽  
Author(s):  
Sarah E. Clifford ◽  
Vanny Tiwow ◽  
Aleasia Gendron ◽  
Marcel Maeder ◽  
Monica Rossignoli ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Reaction Pathway ◽  
Formation Constants ◽  
Bidentate Ligand ◽  
Dimethyl Formamide ◽  
X Ray ◽  
Spectrophotometric Titrations ◽  
In Trans ◽  
Monodentate Coordination ◽  
Competing Reactions

Complexation of the symmetric cyclic diamine piperazine (1,4-diazacyclohexane) has been examined in dry dimethyl formamide by spectrophotometric titrations (with Cu2+, Ni2+) to define formation constants, and by stopped-flow kinetics to define the complexation rates and reaction pathway. Initial formation of a rarely observed η1-piperazine intermediate occurs in a rapid second-order reactions. This intermediate then undergoes two competing reactions: formation of (chelated) η2-piperazine (ML) or the formation of (bridging) μ-piperazine (in M2L and M2L3, speciation depending on relative concentrations). Protonation constants and formation constants for complexation in water of N-ethylpiperazine and thiomorpholine (1-aza-4-thiocyclohexane, tm) have been determined by potentiometric titration; 1:1 complexes with first-row M2+ display a log K from ~4 to 6, with speciation that suggests chelation of the heterocycles may be involved. Complexation of thiomorpholine has been further probed by the synthesis of PdII complexes. The N-monodentate coordination mode has been confirmed in trans-[Pd(tm)2Br2] by an X-ray crystal structure. Complexation of N-(2-aminoethyl)piperazine to CuII as a bidentate ligand involving the primary and tertiary amines is also defined by an X-ray crystal structure.

scholarly journals Multi Component Reactions under Increased Pressure: On the Mechanism of Formation of Pyridazino[5,4,3-de][1,6]naphthyridine Derivatives from Reaction of Malononitrile, Aldehyde and 2-Oxoglyoxalarylhydrazones in Q-Tubes

2017 ◽  
Author(s):  
Majdah A. AL-Johani ◽  
Khadijah M. Al-Zaydi ◽  
Sameera M. Mousally ◽  
Norah F. Alqahtani ◽  
Mohamed H. Elnagdi
Keyword(s):  
Crystal Structure ◽  
Reaction Pathway ◽  
Aromatic Aldehydes ◽  
Reaction Products ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Alternate Pathway ◽  
Considerable Research ◽  
Increased Pressure ◽  
Chemical Evidence

The considerable biological and medicinal activities of pyridazines has stimulated considerable research on efficient syntheses of these derivatives. In the last decade, microwave irradiation has generally been used for the energy source. As demonstrated in recent studies, pressure reactor “Q-tubes” may be used to accelerate several of these reactions in a more optimal and safer manner (compared to microwaves). In these studies there has been postulated a pathway for the formation of pyridazino[5,4,3-de][1,6]naphthyridine derivatives . In this paper we consider this pathway, and an alternate pathway, for several reactions. Contrary to the suggestion in these studies the pathway in which initial dimerization of malononitrile was postulated could be excluded based on chemical evidence. The reactions performed were the reaction of arylhydrazonals 1a,b with benzylidinemalononitrile which afforded in Q-tube the 3-acyl-4-aryl-1-phenyl-6-amino-1,4-dihydropyridazines, and the reaction of arylhydrazonals 1a,b, malononitrile 9 and aromatic aldehydes 10a-g in Q-tubes which afforded the tricyclic systems 12a-n whose structure could be established by X-ray crystal structure determination. In conclusion, we have added to the work of the recent studies by excluding a reaction pathway for one of their reaction products.

Synthese, Schwingungs- und Massenspektren von Et2Sn(O2PR2)2 (R = Me, Ph); Kristallstruktur von Et2Sn(O2PPh2)2 / Synthesis, Vibrational Spectra and Mass Spectra of Et2Sn(O2PR2)2 (R = Me, Ph); Crystal Structure of Et2Sn(O2PPh2)2

1996 ◽  
Vol 51 (8) ◽  
pp. 1111-1116 ◽  
Author(s):  
Abdel-Fattah Shihada ◽  
Frank Weller
Keyword(s):  
Crystal Structure ◽  
Vibrational Spectra ◽  
Mass Spectra ◽  
Structure Refinement ◽  
Base Peak ◽  
Trans Position ◽  
X Ray Diffraction ◽  
X Ray ◽  
Octahedral Environment ◽  
In Trans

Et2Sn(O2PPh2)2 has been synthesized by the reaction of (Et2ClSn)2O with Ph2POCl in toluene and by the treatment of (Et2ClSn)2O or Et2SnCl2 with HO2PPh2 in methanol. The reaction of Et2SnO with HO2PMe2 in toluene was used to prepare Et2Sn(O2PMe2)2. An X-ray diffraction study of Et2Sn(O2PPh2)2 (space group P1̅, Z = 1, a = 559,9( 1), b = 983,7(1), c = 1262,4(l)pm, α = 81,85( 1 )°, β = 79,79( 1)°, γ = 75,00(1)°; structure refinement with 2662 independent reflections, R = 0.055) shows that the structure is polymeric and the O2PPh2 ligands function as double bridges between the tin atoms leading to the formation of centrosymmetric Sn2O4P2 eight-membered rings. The ethyl groups are in trans-position in the resulting octahedral environment around tin. The I. R. and Raman spectra of Et2Sn(O2PR2)2 (R = Ph, Me) have been discussed and assigned. The mass spectra of Et2Sn(O2PR2)2 show Sn(O2PR2)+ as the base peak.

Donor-Akzeptor-Komplexe von WCl3(N3S2) und WBr3(N3S2). Die Kristallstruktur von WCl3(N3S2) ·THF/ Donor Acceptor Complexes of WCl3(N3S2) and WBr3 (N3S2).The Crystal Structure of WCl3(N3S2)·THF

1987 ◽  
Vol 42 (8) ◽  
pp. 943-946 ◽  
Author(s):  
Abderraouf Khabou ◽  
Wolfgang Willing ◽  
Ulrich Müller ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Ir Spectra ◽  
Dihedral Angle ◽  
Trans Position ◽  
X Ray Diffraction ◽  
Tungsten Atom ◽  
X Ray ◽  
Cell Dimensions ◽  
Donor Acceptor ◽  
In Trans

AbstractThe donor acceptor complexes WC13(N 3S2)-L (L = TH F, pyridine), and [WCl3(N3S2)]2 · dipy are prepared from WCl3(N3S2) and the corresponding donor molecules. WBr3(N3S2) ­ THF is formed by the reaction of WCl3(N3S2) THF with BrSiMe3. The complexes have been characterized by their IR spectra. The crystal structure of WCl3(N3S2) THF was determ ined by X-ray diffraction. It crystallizes monoclinically in the space group P21/c with four formula units per unit cell (1903 observed, independent reflexions, R = 0.031); the cell dimensions are a = 1072.0. b = 1007.2, c = 1128.9 pm; β = 94.84°. The tungsten atom is a member of a nearly planar WN3S2 ring with WN bond distances of 180 and 184 pm, which correspond to double bonds. The sixfold coordination of the W atom is completed by three chlorine atoms and the O atom of the tetrahydrofuran ligand, which is coordinated in trans-position to one of the N atoms; the THF molecules forms a dihedral angle of 40.1° with the WN3S2 ring.

Synthesis, Spectral, Thermal and Structural Characterization of the Copper(II) Saccharinato Complex of 2–Aminopyrimidine, [Cu(sac–O)2(ampym–N)2(H2O)2]·2ampym

2006 ◽  
Vol 61 (2) ◽  
pp. 153-158
Author(s):  
Okan Zafer Yeşilel ◽  
Halis Ölmez ◽  
Hümeyra Paşaoğlu ◽  
Gökhan Kaştaş ◽  
Orhan Büyükgüngör
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Π Interactions ◽  
Hydrogen Bonding Interactions ◽  
Vis Spectroscopy ◽  
Phenyl Rings ◽  
In Trans

AbstractBis(2-aminopyrimidine-N)diaquabis(saccharinato-O)copper(II) di(2-aminopyrimidine), [Cu(sac-O)2(ampym-N)2(H2O)2] · 2ampym was synthesized and characterized by means of elemental analysis, IR and UV-vis spectroscopy, magnetic susceptibility, simultaneous TG, DTG, DTA techniques, and X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c [a = 7.4697(5), b = 10.1679(5), c = 22.743(2)Å , β = 92.844(5), Z = 2, R = 0.0275, wR= 0.0757, V = 1725.26(19) Å3]. The copper atom is bonded to two ampym N atoms and two sac O atoms as well as to two water O atoms in trans positions in the geometry of a distorted octahedron. There are also two ampym moieties as solvate molecules in the unit cell. The crystal structure is stabilized by N-H· · ·O, O-H· · ·N and C-H· · ·O type hydrogen bonding interactions. Intermolecular π−π interactions between the phenyl rings of ampym groups and C-H· · ·π interactions also support the packing of the molecules. The thermal decomposition of the complex has been studied.

Die Kristallstruktur von PPh4[MoOCl4(OCHNMe2)] / The Crystal Structure of PPh4[MoOCl4(OCHNMe2)]

1986 ◽  
Vol 41 (4) ◽  
pp. 523-526 ◽  
Author(s):  
Dieter Fenske ◽  
Kay Jansen ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Carbon Tetrachloride ◽  
Octahedral Geometry ◽  
Distorted Octahedral Geometry ◽  
Dimethyl Formamide ◽  
Structural Investigations ◽  
X Ray ◽  
Distorted Octahedral ◽  
Cell Dimensions ◽  
Ray Methods

Green crystals of the title compound are formed in the reaction of (PPh4)2 [Mo2(O2C -Ph)4Cl2] ·2 CH2Cl2 with dimethyl formamide/carbon tetrachloride in the presence of water. According to the structural investigations by X-ray methods PPh4[MoCl4(O CHNMe2)] crystallizes orthorhombically in the space group C2221 with four formula units per unit cell (3132 observed, independent reflexions, R - 0.068). The cell dimensions are a = 792.1 pm, b = 1656.8 pm, c = 2211.3 pm. The structure consists of PPh4⊕ cations and anions [MoOCl4(OCHNMe2)]⊖, in which the coordination sphere of the molybdenum atom is of distorted octahedral geometry. The ligands are four equatorial chlorine atoms, one terminal O atom (Mo = O 165 pm) and the O atom of the dimethyl formamide molecule (MoO 232 pm). The IR spectrum is reported

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