Showing papers on "Tetrahedral molecular geometry published in 1997"
TL;DR: In this article, the use of three dicyanobenzene derivatives as bridging ligands was used to synthesize four copper coordination polymers, [Cu(dchq)2]-ClO4)(Me2CO)2 (1; dchq = 1,2-dicyanohydroquinone), [Cu[ipn]2]-PF6)(Me 2CO) (2; ipn = 1.3-dimethylterephthalonitrile), and [cu(dmtpn)2](X)(dmt
Abstract: With the use of three dicyanobenzene derivatives as bridging ligands, four copper(I) coordination polymers, [Cu(dchq)2](ClO4)(Me2CO)2 (1; dchq = 1,2-dicyanohydroquinone), [Cu(ipn)2](PF6)(Me2CO) (2; ipn = 1,3-dicyanobenzene), and [Cu(dmtpn)2](X)(dmtpn)(THF) (3a (X = BF4), 3b (X = ClO4); dmtpn = 2,5-dimethylterephthalonitrile) were synthesized and characterized. Single-crystal X-ray analyses revealed that all copper(I) ions in these complexes have tetrahedral geometry and are coordinated by four ligands which also coordinate to the next copper ions, resulting in the formation of coordination polymer compounds. The polymer framework of 1 consists of one-dimensional chains that run along the a-axis direction and weakly interact with each other through π−π interactions between the dchq molecules and through hydrogen bonding. 2 has a two-dimensional sheet with a square arrangement of copper(I) ions. Stacking of the square lattice in the c-axis direction forms cavities in which the acetone molecules and PF6- ani...
72 citations
TL;DR: In this article, the A2CuX4 lattice with diprotonated 3-picolylamine and X = Cl- or Br-, where the cation is dipronated 3picolyamine, was shown to be an unusual variant of the normal antiferrodistortive A2cuX4.
Abstract: The compounds (C6N2H10)CuX4, where the cation is diprotonated 3-picolylamine and X = Cl- or Br-, form an unusual variant of the normal antiferrodistortive A2CuX4 lattice [(C6N2H10)CuCl4, orthorhombic, Pna21, a = 7.747(1), b = 24.960(2), and c = 17.041(1) A, Z = 12; (C6N2H10)CuBr4, orthorhombic, Pna21, a = 8.133(1), b = 26.129(1), and c = 17.148(1) A, Z = 12]. The structures contain ribbons of the antiferrodistortive sheets which are six copper atoms wide. The central four Cu(II) ions have the usual elongated octahedral coordination, while on each edge are CuX42- ions which have a distorted tetrahedral geometry. Long Cu···X interactions (4.000 and 4.124 A for the Cl and Br salts, respectively) between these terminating anions link the ribbons together into sheets. The organic cations provide overall stability to the lattice and link adjacent sheets together, forcing the existence of short two-halide X···X contacts between sheets (average Cl···Cl = 4.629 A, Br···Br = 4.425 A). While the changes in the semic...
61 citations
TL;DR: In this article, the first rotationally resolved photoelectron spectra for a tetrahedral molecule were obtained and the analysis of the rotational structure was accompanied by a description of the observed symmetry selection rules and propensity rules for core rotational angular momentum changes that characterize the photoionization process.
Abstract: High-resolution zero-kinetic-energy photoelectron spectroscopy has been used to record the transition between the lowest bound state (3s 2A1) of the perdeuterated ammonium radical (ND4) and the X 1A1 ground vibronic state of the perdeuterated ammonium ion (ND4+). The spectra obtained are the first rotationally resolved photoelectron spectra ever measured for a tetrahedral molecule. The analysis of the rotational structure is accompanied by a description of the observed symmetry selection rules and propensity rules for core rotational angular momentum changes that characterize the photoionization process. Rotational constants (B0=2.8560±0.0037 cm−1 and B0+=2.9855±0.0037 cm−1) and centrifugal distortion constants (D0=(4.78±1.4)×10−5 cm−1 and D0+=(4.77±1.5)×10−5 cm−1) have been determined for the 3s 2A1 state of ND4 and the X 1A1 state of ND4+, respectively. The ionic rotational constant is in good agreement with the value B0+=2.9787±0.0029 cm−1 determined indirectly by Crofton and Oka (J. Chem. Phys. 86, ...
59 citations
TL;DR: In this paper, the pendant arms of the disubstituted bispidine (3,7-diazabicyclo[3.3.1]nonane) backbone need to form six-membered chelate rings with the metal to allow a distorted tetrahedral geometry.
Abstract: Molecular mechanics calculations were used to compute the structural
properties of a new type of very rigid tetradentate ligand for tetrahedral
co-ordination geometries. The calculations indicate that the pendant arms
of the disubstituted bispidine (3,7-diazabicyclo[3.3.1]nonane) backbone
need to form six-membered chelate rings with the metal to allow a distorted
tetrahedral geometry. Smaller rings lead to five- (trigonal bipyramidal) or
six-co-ordinate (octahedral) transition-metal compounds. The quality of
these predictions is supported by the experimentally determined structure
of a cobalt(II) compound of the ligand with co-ordinated
pyridine substituents (five-membered chelate rings) and an additional
bidentate nitrate ligand. Comparison of the computed structures with the
crystal structure of the cobalt(II) compound and with that of a
ligand with methyl-protected phenyl substituents supports the rigidity of
the bispidine backbone and indicates that rotation of co-ordinating side
chains around a C–C single bond is the only flexibility in these
ligands.
58 citations
TL;DR: In this paper, X-ray structure analysis of compound 2 a and ab initio calculations on the model compounds [Os(SiR3)H3(PH3)3] reveal a trigonal distortion along the Os-Si axis from an idealised tetrahedral geometry for the central OsSiP3 heavy-atom skeleton.
Abstract: The compounds [M(SiR3)H3(PPh3)3] (1: M = Ru, R = 1 - NC4H4 = pyr; 2a-c: M = Os, R = pyr, Et, Ph) are prepared through reaction of either [RuH2(PPh3)4] or [OsH4(PPh3)3] with the appropriate silane HSiR3 (3a-c: R = pyr, Et, Ph). The X-ray structure analysis of compound 2 a and ab initio calculations on the model compounds [Os(SiR3)H3(PH3)3] (4a-c: R = H, NH2, pyr) reveal a trigonal distortion along the Os-Si axis from an idealised tetrahedral geometry for the central OsSiP3 heavy-atom skeleton. The structure can be described as two face-shared octahedra, one based on osmium (OsH3P3) and the other based on silicon (SiH3N3). Studies of the bonding situation in 2 a reveal that the N-pyrrolyl substituents have a marked shortening effect on the osmium-silicon distance (229.3(3) pm) and that each of the three hydride ligands participates in partial three-centre bonding involving osmium, silicon and hydrogen. 1H, 13C, 29Si and 31P NMR spectra were used to determine the solution structures of complexes 1 and 2 a.
53 citations
TL;DR: In this article, structural analysis of [Ph2P(4-methylbenzylide)2]2Ba represents the first organobarium compound not belonging to the cyclopentadienyl series.
43 citations
TL;DR: In this paper, the X-ray crystal structure of CuX(C5H5NS(p-Tol3P)]2 has been determined and the interatomic important parameters are: Cu P= 2.243(3), Cu S, 2.393(4), 2.425(4) and 2.603(2), C S.
37 citations
TL;DR: In this article, the vibration-rotation states of a tetrahedral molecule in a field of D3h symmetry were studied by an extended group theory, where symmetry adapted rotational wave functions for the ground and the triply degenerate excited vibrational states were constructed.
Abstract: The vibration-rotation states of a tetrahedral molecule in a field of D3h symmetry are studied by an extended group theory. Symmetry adapted rotational wave functions for the ground and the triply degenerate excited vibrational states are constructed. The crystal field potential is derived explicitly for a tetrahedral molecule in a hexagonal close-packed crystal. As an example, the rovibrational energy states of methane in solid parahydrogen are computed. Optical selection rules are also derived from the theory.
36 citations
TL;DR: The crystal structure of Cs2[Co2(nta)2(μ-OH)2] · 4H2O (nta = nitrilotriacetate) has been determined from three-dimensional X-ray diffraction data.
30 citations
TL;DR: The first metal complex of TTF or BEDT-TTF analogs, in which the sulfur atom in a five- or six-membered ring directly coordinates to the silver ion, was synthesized and the molecular structure and packing were characterized crystallographically as mentioned in this paper.
28 citations
TL;DR: An anaerobic optical spectroscopic, competitive metal binding assay is employed to determine the coordination geometry and association constants (Ka) for the binding of Co(II) to wild-type gp32 and a series of zinc ligand substitution mutants and reveals that the local protein structure restricts accommodation of a non-native metal complex in a ligand-specific manner.
Abstract: Phage T4 gene 32 protein (gp32) is a zinc metalloprotein which binds cooperatively and preferentially to single-stranded nucleic acids and functions as a replication and recombination accessory protein. Zn(II) coordination by gp32 employs a His-Cys3 metal ligand donor set derived from the His64-X12-Cys77-X9-Cys87-X2-Cys90 sequence in the ssDNA-binding core domain of the molecule. Crystallographic studies reveal that His64 and Cys77 are derived from two independent beta-strands within a distorted three-stranded beta-sheet and are relatively more buried from solvent than are Cys87 and Cys90, which are positioned immediately before and within, respectively, an alpha-helix. In an effort to understand the origin of the stability of the metal complex, we have employed an anaerobic optical spectroscopic, competitive metal binding assay to determine the coordination geometry and association constants (Ka) for the binding of Co(II) to wild-type gp32 and a series of zinc ligand substitution mutants. At pH 7.5, 25 degrees C, wild-type gp32 binds Co(II) with a Ka approximately 1 x 10(9) M-1. Competition experiments reveal that Ka for Zn(II) is 3.0 (+/-1.0) x 10(11) M-1. We find that all non-native metal complexes retain tetrahedral or distorted tetrahedral coordination geometry but are greatly destabilized in a manner essentially of whether a new protein-derived coordination bond is formed (e.g., in H64C gp32) or not. Co(II) binding isotherms obtained for three His64 substitution mutants, H64C, H64D, and H64N gp32s, suggest that each mutant forms a dimeric Cys4 tetrathiolate intermediate complex at limiting [Co(II)]f, each then rearranges at high [Co(II)]f to form a monomolecular site of the expected geometry and Ka approximately 1 x 10(4) M-1. Like the His64 mutants, C77A gp32 appears to form at least two types of complexes over the course of a Co(II) titration: one with octahedral coordination geometry formed at low [Co(II)]f, with a second tetrahedral or five-coordinate site formed at higher [Co(II)]f. Apo C87S and C90A gp32s, in contrast, each form a single complex at all [Co(II)]f, consistent with Cys2-His-H2O tetrahedral geometry of Ka approximately (1-2) x 10(5) M-1. These studies reveal that the local protein structure restricts accommodation of a non-native metal complex in a ligand-specific manner. The implications of this work for de novo design of zinc complexes in proteins are discussed.
TL;DR: The second-order rate constants for the reaction between hydrogen sulfide ion and phenoxide ion with 4-nitrophenyl esters of substituted benzoic substituent in 10% acetonitrile-water (v/v) solution obey Hammett correlations as mentioned in this paper.
Abstract: The second-order rate constants for the reaction between
hydroxide
ion and phenoxide ion with 4-nitrophenyl esters of substituted benzoic
acids in 10% acetonitrile–water (v/v) solution obey Hammett
σ correlations. The values of the Hammett ρ
of 1.67 (kArO) and 2.14 (kOH)
are consistent with a large change in hybridization at the central
carbon by comparison with the ρ value for a standard
reaction where a full sp2 to sp3 change occurs.
The transition state for the concerted reaction thus has a substantially
tetrahedral geometry. The observation of the anti-Hammond
effect whereby the ρ value for the hydroxide ion exceeds
that of the less reactive phenoxide ion is consistent with a concerted,
ANDN, mechanism for these reactions. A stepwise
mechanism, AN + DN, is unlikely to
yield a measurable break in the Hammett correlation for a change in the
benzoyl substituent if the partitioning of the putative tetrahedral
intermediate involves forward and reverse reactions with Hammett
correlations possessing similar ρ values.
TL;DR: In this article, the neutral dppfFe(NO)2 (1), the novel cationic [dppfCo(NO), SbF6] (2), as well as the dppfeFe(CO), 1,1′-bis-(diphenylphosphino)ferrocene) complexes were prepared and characterized.
TL;DR: In this article, the effect of varying the bidentate ligand upon the reaction of unconjugated dienes with (R2P(CH2)nPR2)Fe0 species has been investigated.
TL;DR: Bis{μ-[(dimercaptomethylene)propanedinitrilato-S,S‘]}tetrakis(4-methylpyridine)dizinc(II)−chloroform was obtained by the reaction of ZnCl2 with (NC)2CCS2K2 in a solution of 4-methyl pyridine, EtOH, and CHCl3.
Abstract: Bis{μ-[(dimercaptomethylene)propanedinitrilato-S,S‘]}tetrakis(4-methylpyridine)dizinc(II)−chloroform was obtained by the reaction of ZnCl2 with (NC)2CCS2K2 in a solution of 4-methylpyridine, EtOH, and CHCl3. The zinc atom in the dimer has a tetrahedral geometry. Each of the two (dimercaptomethylene)propanedinitrilato S atoms bridges two bis(4-methylpyridine)zinc moieties to give an eight-membered ring even though an adduct has effectively been formed. The Zn−N bond lengths are 2.035(4) and 2.077(3), A and those of Zn−S are 2.317(1) and 2.321(1) A, respectively.
TL;DR: In this paper, a tetrameric compound with distorted tetrahedral geometry was obtained by electrochemical oxidation of copper metal in an acetonitrile solution of the neutral ligand.
TL;DR: In this article, the reaction of NbCl5, NaStBu, Se and Et4NCl in CH3CN in a 1:6:1:1.6 molar ratio is described.
TL;DR: A new heteroditopic cryptand (L) has been synthesized in high yields as mentioned in this paper at 5 °C and in absence of any templating metal ion, bytripod-tripod Schiff-base condensation of tris(3-aminopropyl)amine and 2,2′,2″-nitrilotris(ethyleneoxy)tris(benzaldehyde)======Following by reduction in situ with NaBH============
Abstract: A new heteroditopic cryptand (L) has been synthesized in high yields,
at 5 °C and in absence of any templating metal ion, by
tripod–tripod Schiff-base condensation of tris(3-aminopropyl)amine
and 2,2′,2″-nitrilotris(ethyleneoxy)tris(benzaldehyde)
followed by reduction in situ with NaBH
4
. The
molecule has an endo-endo conformation with a distance of 5.291
A between the two bridgehead nitrogens. The cryptand forms
mononuclear cryptates of the general formula
[ML][ClO
4
]
2
with copper(II) and
zinc(II) perchlorates. The crystal structure of
[ZnL][ClO
4
]
2
·2H
2
O was
determined. The Zn
II
occupies the N
4
end of the
cavity in an almost ideal tetrahedral geometry. The blue
copper(II) cryptate exhibits ligand-field bands at 875 and
745 nm and a ligand-to-metal charge transfer at 275 nm in acetonitrile
solution at 298 K indicative of pseudo-tetrahedral CuN
4
co-ordination. However, its EPR spectral characteristics in the solid
state or in solution are typical of a magnetically concentrated
complex.
TL;DR: In this article, the edge-bridged tetrahedral geometry of five-coordinate d0 complexes with strong π-donors D is analyzed with extended Huckel methodology as well as density functional theory.
Abstract: The edge-bridged tetrahedral geometry of five-coordinate d0 complexes [MD2L3] with strong π-donors D is analyzed with extended Huckel methodology as well as density functional theory. It is shown that this geometry, also encountered in bent metallocene systems [MCp2L3], can be considered as a distortion of a regular trigonal bipyramid arising from a second-order Jahn−Teller distortion of e‘ symmetry (in D3h) and corresponds to a deformation along a reversed-Berry pathway. This model was tested with a structure-correlation analysis of all experimentally determined [MD2L3] structures, thus allowing a mapping of the reversed-Berry pathway. The catalytic potential of these complexes and their isolobal relationship to [MCp2L3] are emphasized.
TL;DR: In this article, Leroyet et al. further extend a previous formalism, the construction of a dipole function adapted to tetrahedral molecules, based on an algebraic construction of symmetrized tensor operators.
TL;DR: In this article, a mixture of NaI and LnCl3 was used to give five monomeric complexes (Me3Si)2C5H3]2LnI(THF) (Ln = La (1), Sm (2), Y (3), Er (4), Lu (5)) in 50-69% yield.
TL;DR: The quantitative two-step electrochemical oxidation of 2 at controlled potential in CH(3)CN also leads to 11: an ECE mechanism, in which the diprotonated species plays a key role, is proposed.
Abstract: Several novel diazadioxa ferrocenyl derivatives have been prepared along with their previously unknown electroactive precursor [(C5H5)Fe(C5H4CH2N(CH3)(CH2)2OCH2−)]2 (2). Di-N,N‘-protonated and -methylated species [2(H)2][X]2 (3a−c) (X = CF3SO3, BF4, PF6) and [2(Me)2][CF3SO3]2 (5), and N−H−N monoprotonated species [2H][X] (4a−c) have been isolated in high yield. The efficient syntheses of compounds [2Na][PF6] (6), [2Cu][CF3SO3] (7), [2Ag][CF3SO3] (8), and [2MCl2] (M = Zn, Hg) (9, 10) are reported. The crystal structure of complex 7 has been determined by X-ray analysis at 180 K. Crystal data: monoclinic P21/c, with a = 11.511(2) A, b = 19.613(2) A, c = 14.493(2) A, β = 88.32(2)°, V = 3273.2(1) A3 , Z = 4; R = 0.034, Rw = 0.039 for 3379 observations and 407 variable parameters. The copper(I) atom, bound to the two O and two N atoms of the ferrocenyl ligand, is in a very distorted tetrahedral geometry with a large N(1)CuN(2) angle (163.1(2)°). In cyclic voltammetry, 4a−c undergo two quasi-reversible (Fe(II)...
TL;DR: The luminescent dinuclear copper complex was obtained from the reaction of CuI with oesq, in which the two copper(I) atoms are triply-bridged, each in a distorted tetrahedral geometry with a Cu…Cu distance of 2.550(1) A as mentioned in this paper.
Abstract: The luminescent dinuclear copper(I) complex [Cu
2
I
2
(oesq)] (oesq = 8,8′-[oxybis(ethylenesulfanyl)]diquinoline) was obtained from the reaction of CuI with oesq, in which the two copper(I) atoms are triply-bridged, each in a distorted tetrahedral geometry with a Cu…Cu distance of 2.550(1) A.
TL;DR: In this paper, the authors compared the results of ab initio calculations of equilibrium geometry with a large (triple zeta valence + polarisation) basis, at both the SCF and MP2 levels, with known experimental structural and dipole moment data.
TL;DR: The CoCl2(C5H8N2Se)2 compound as mentioned in this paper shows a tetrahedral geometry around the cobalt ion and the mean Co-Cl and Co-Se distances are 2.277 and 2.456, respectively.
Abstract: The crystal structure of the title compound, [CoCl2(C5H8N2Se)2], shows a discrete molecular structure with tetrahedral geometry around the cobalt ion. The mean Co—Cl and Co—Se distances are 2.277 (3) and 2.456 (3) A, respectively. Bond angles around the Co atom range from 101.1 (1) to 120.0 (1)°. Ring distances and angles in the ligand compare favorably with the literature values of analogous compounds, and show significant increases from values observed in the uncoordinated selone. However, the mean C—Se bond distance of 1.88 (2) A shows no significant difference from the free ligand. Other corresponding bond distances and angles show no significant differences between the free and coordinated ligands.
TL;DR: Using the delocalised wavefunctions from Part 3, for a series of molecules of type MX 2 Y 2 where M is tetravalent, and X, Y are either H, Me or halogen, with a triple-zeta plus polarisation basis and either SCF of MP2 methods, the wave functions were converted to localised orbitals by the Foster-Boys method, which enabled the LMO to be subject to population analysis for changes in hybridisation in the individual total density of the MX and MY bonds.
TL;DR: In this paper, a first-principles study of nitrite sodalite, a synthetic zeolite, was presented, where the NO-2 anions are hosted in octahedral cavities typical of such crystals and each anion is surrounded by four Na cations in a tetrahedral geometry.
Abstract: We present a first-principles study of nitrite sodalite, a synthetic zeolite. The NO-2 anions are hosted in octahedral cavities typical of such crystals, and each anion is surrounded by four Na cations in a tetrahedral geometry. We found that NO-2 is in a rotational state inside the zeolite’s cages. This rotational state explains the orientational disorder experimentally detected in nitrite sodalite.
TL;DR: In this paper, isothermal-isobaric molecular dynamics simulations of molecular crystal SnI 4 are carried out based on a model consisting of rigid tetrahedral molecules interacting via van der Waals forces.
Abstract: Isothermal-isobaric molecular dynamics simulations of molecular crystal SnI 4 are carried out based on a model consisting of rigid tetrahedral molecules interacting via van der Waals forces. The behavior of the crystal upon an increase in pressure is satisfactorily reproduced on both microscopic and macroscopic scales in the pressure regime in which the low-pressure phase is stable. In particular the compression curve obtained is in excellent agreement with the experimentally determined one. Upon further increase in pressure, however, no symmetry change is detected in the present simulations over the pressure regime in which the phase transformation and the subsequent solid state amorphization are experimentally found to take place.
TL;DR: The 1∶1 stoichiometric addition of the bidentate phosphine ligand 2,2-dimethyl-2-sila-1,3-bis(diphenylphosphino)propane (L2) to a range of cadmium(II) salts produced a series of moisture-sensitive complexes of general formula [CdX2(L2)] as discussed by the authors.
Abstract: The 1∶1 stoichiometric addition of the bidentate phosphine ligand 2,2-dimethyl-2-sila-1,3-bis(diphenylphosphino)propane (L2) to a range of cadmium(II) salts produced a series of moisture-sensitive complexes of general formula [CdX2(L2)] (X = Cl 1, Br, I, SCN or NO3). These complexes have been investigated by vibrational and multinuclear (31P and 113Cd) NMR spectroscopy and by X-ray crystallography. Complex 1 crystallises in the orthorhombic space group P212121, with a = 9.2862(10), b = 15.386(2), c = 20.724(3) A, U = 2960.9(6) A3 and Z = 4. The metal centre exhibits four-co-ordinate, tetrahedral geometry, with the ligand bound in a bidentate manner. Both the solution- and solid-state cross-polarisation magic angle spinning 31P NMR spectra of the complexes show clearly resolved 113Cd–31P and 111Cd–31P one bond couplings in a 113Cd∶111Cd ratio of 1.044∶1.046 as expected. Vibrational spectroscopy indicates that each complex is mononuclear, with no evidence for bridging species; [Cd(NO3)2(L2)] features monodentate nitrate groups. The addition of 2 equivalents of the ligand to cadmium perchlorate yields a complex which has been established as [Cd(L2)2][ClO4]2 by spectroscopic and conductance studies.
TL;DR: ZnCl2(C7H10N2S) as discussed by the authors shows a discrete molecular structure with tetrahedral geometry around the zinc ion, and the mean ZnCl and ZnS distances are 2.259 and 2.372, respectively.
Abstract: The crystal structure of the title compound, [ZnCl2(C7H10N2S)2], shows a discrete molecular structure with tetrahedral geometry around the zinc ion. The mean Zn—Cl and Zn—S distances are 2.259 (4) and 2.372 (4) A, respectively. Bond angles around the zinc ion range from 102.8 (1) to 113.7 (1)°. Ring distances and angles in the ligand compare favorably with literature values of analogous compounds, and the mean C—S bond distance of 1.71 (1) A is close to the average distance of 1.72 A observed for several dialkylimidazolethione complexes of main group and transition metal halides.