Quinquedentate Coordination of 3-[(2'-Amino-ethyl)amino]-2-[(2″-aminoethyl)aminomethyl]propionic Acid (LH). Crystal Structure of trans-[Co(L)Cl][ClO4].H2O And Molecular Mechanics Examination of Isomers

1994 ◽  
Vol 47 (5) ◽  
pp. 817 ◽  
Author(s):  
PV Bernhardt ◽  
TW Hambley ◽  
GA Lawrance ◽  
KJ Molloy

The anion (1c) of the branched polyamino acid 3-[(2′-aminoethyl)amino]-2-[(2″-aminoethyl)- aminomethyl ] propionic acid (1b) binds as a quinquedentate ligand to cobalt(III). Reaction with cobalt(II) chloride, followed by oxidation and acidification, yields exclusively one isomer of [Co(1c) Cl ]+. The complex was crystallized readily as a perchlorate monohydrate salt, in the monoclinic space group P 21/n, a 7.921(2), b 17.357(4), c 11.852(4) Ǻ, β 107.25(2)°, Z = 4; a single-crystal X-ray structure determination was refined to R 0.033 for 2099 `observed' reflections. The carboxylate and two adjacent secondary amines occupy an octahedral face, with the chloro ligand trans to the carboxylate , and the secondary amines adopt R,S stereochemistries. The Co-O distance [1.901(2) Ǻ] is at the short end of the range of cobalt- carboxylate bonds, and Co-N distances [average 1.944 Ǻ (primary amines), average 1.950 Ǻ (secondary amines)] are slightly shorter than average for Co-N bonds. The Co- Cl distance is 2.255(1) Ǻ. Molecular mechanics examination of all possible isomers and conformers of [Co(1c) Cl ]+ and of the related pentaamine 1,5,9-triamino-5-methyl-3,7-diazanonane (2) indicate a greater variation in strain energy across the range of isomers and conformers in the latter more strained system.

1994 ◽  
Vol 47 (5) ◽  
pp. 829 ◽  
Author(s):  
TW Hambley ◽  
TW Hambley ◽  
GA Lawrance ◽  
GA Lawrance ◽  
M Maeder ◽  
...  

The branched, potentially quinquedentate , 5-methyl-3,7-diazanonane-1,5,9-triamine (1) reacts in hot water with rhodium(III) chloride to yield fac -[ Rh (H2(1))Cl3]2+. Only upon extended reflux for several weeks is coordination as a quinquedentate achieved. The fac complex was crystallized readily as a mixed chloride perchlorate trihydrate salt, in the triclinic space group Pī , a 8.666(2), b 10.319(2), c 12.558(3) Ǻ, α 94.34(2), β 98.86(2), γ 97.75(2)°, Z = 2; a single-crystal X-ray structure determination was refined to Rw 0.037 for 3703 'observed' reflections. The central primary amine and two adjacent secondary amines occupy an octahedral face, with the chloro ligands then necessarily fac also. The Rh -N distances vary, with the shortest distance to the primary amine [2.023(2)Ǻ] rather than to the secondary amines [2.066(2), 2.077(2) Ǻ], as do the Rh-Cl distances [range 2.345(1)-2.369(1)Ǻ]. The two primary amines on the chain terminals remain uncoordinated, the central facially capping unit preferring coordination first, possibly indicating a general intermediate for coordination of polydentate l igands containing this type of unit.


Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.


1981 ◽  
Vol 36 (10) ◽  
pp. 1208-1210 ◽  
Author(s):  
Hartmut Köpf ◽  
Joachim Pickardt

Abstract The molecular structure of the bridged [1]-titanocenophane 1,1'-dimethylsilylene titanocene dichloride, (CH3)2Si(C5H4)2TiCl2, has been investigated by an X-ray structure determination. Crystal data: monoclinic, space group C2/c, Z = 4, a = 1332.9(3), 6 = 988.7(3), c = 1068.9(3) pm, β = 113.43(2)°. The results are compared with the structural dimensions of similar compounds: 1,1'-methylene titanocene dichloride, CH2(C5H4)TiCl2, with the unbridged titanocene dichloride, (C5H5)2TiCl2 and the ethylene-bridged compound (CH2)2(C5H4)2TiCl2


1986 ◽  
Vol 41 (10) ◽  
pp. 1191-1195 ◽  
Author(s):  
Ute Patt-Siebel ◽  
Somluck Ruangsuttinarupap ◽  
Ulrich Müller ◽  
Jürgen Pebler ◽  
Kurt Dehnicke

S5N5[SnCl5(CH3CN)] is prepared by the reaction of SnCl2 with trithiazyl chloride in acetonitrile suspension. The compound is characterized by its IR spectrum, the 119Sn Mössbauer spectrum and by an X-ray crystal structure determination (1851 observed, independent reflexions, R = 0.024). S5N5[SnCl5(CH3CN)] crystallizes in the monoclinic space group P21/n with Z = 4 and the lattice dimensions a = 758.8; b = 1574.6; c = 1429.1 pm; β = 97.65°. The compound consists of planar S5N5® cations with the azulene-like structure, and anions [SnCl5(CH3CN)]e in which the tin atom has a distorted octahedral coordination. The bond angle Sn-N ≡ C (168°) is surprisingly small.


1993 ◽  
Vol 48 (7) ◽  
pp. 1009-1012 ◽  
Author(s):  
Kurt Merzweiler ◽  
Harald Kraus

[{Cp(CO)2Fe}SnCl3] reacts with Na2Se in THF to form the compound [{Cp(CO)2Fe}3ClSn3Se4] 1. 1 crystallizes in the monoclinic space group P21/n with 4 formula units per unit cell. The lattice constants are α = 1435.2(7), b = 1124.4(4), c = 1972.7(12) pm, β = 94.59(4)°. According to the X-ray structure determination 1 contains a bicyclic Sn3Se4 framework.


1989 ◽  
Vol 44 (8) ◽  
pp. 903-910 ◽  
Author(s):  
Astrid Görge ◽  
Ute Patt-Siebel ◽  
Ulrich Müller ◽  
Kurt Dehnicke

[WCl4(NCl)]2 reacts in acetonitrile with the trimethylsilyl compounds Me3SiSR (R = Me, Ph), and Me3SiESiMe3 (E = S, Se), with substitution of the chlorine atom of the N-chloronitreno group W=N–Cl and formation of CH3CN–WCl4(NSR) and CH3CN–WCl4(NEN)WCl4–NCCH3, respectively. Excess Me3SiBr reacts with CH3CN–WCl4(NSMe) to afford CH3CN–WBr4(NSMe). [CH3CN–WNCl3]4 was obtained from CH3CN–WCl4(NCl) and N(SiMe3)3. The products were characterized by their IR spectra. Two X-ray crystal structure determinations were also carried out. CH3CN—WCl4(NSMe) forms twinned crystals, and only non-overlapping reflexions of one of the twin individuals were used for the structure determination (846 unique values, R = 0.055). Crystal data: a = 592.4(2), b = 758.8(2), c = 1203.7(8) pm, β = 95.06(4)°, monoclinic, space group P21/m, Z = 2. The compound is a monomer in which the acetonitrile ligand is situated in the trans position to the W≡N–S̱̅–Me group. The bond lengths (W≡N 174(2), N–S 161(2) pm) and bond angles (WNS 176(1), NSC 102.1(9)°) are in agreement with the proposed formula. Crystal data for [CH3CN–WNCl3]4: a = 1009.5(2), b = 1274.5(2), c = 1287.9(2) pm, β = 108.17(1)°, monoclinic, space group P21/c, Z = 2 (2113 unique reflexions, R = 0.057). The compound forms tetrameric units, in which the W atoms form a square and are linked with one another via N atoms at alternating distances (W=N 171(2), W–N 207(2), W–NCMe 238(2) pm).


1995 ◽  
Vol 50 (1) ◽  
pp. 66-70 ◽  
Author(s):  
Inge Pabst ◽  
Peter Sondergeld ◽  
Mirjam Czjzek ◽  
Hartmut Fuess

The title compound has been prepared in two different ways: First, by boiling single crystals of [(C2H5)4N]HgCl3 in a mixture of n-hexane/n-octane [4:1] at T = 350 K, and second, in a synthesis from stoichiometric quantities of the components. X-ray structure analysis gave the stoichiometry [(C2H5)4N]2Hg3Cl8, monoclinic, space group P21, a = 7.538(3), b = 19.909(6), c = 10.274(3) Å, β = 95.13(1)°, V = 1535.7(9) A3, Z = 2. The basic [Hg3Cl8]2--units form broken zig-zag chains along [100]. The Hg–Cl distances within the [Hg3Cl8]2- clusters range from 2.315(3) to 2.755(4) Å. This is a new coordination type for halomercurates.


1988 ◽  
Vol 43 (2) ◽  
pp. 135-137 ◽  
Author(s):  
H.-Jürgen Meyer ◽  
Joachim Pickardt

Ca2[Fe(CN)6] · C6H12N4 · 6H2O crystallizes in the monoclinic space group B2/b with a = 1130,2(4), b = 1373,5(4), c = 1353,0(4) pm and γ = 97,17°. The X-ray single crystal structure determination converged at R = 0.055 (2057 reflections). Each of the four Fe(CN)6 octahedra (Z = 4) in the unit cell is coordinated by six Ca atoms with mean NCYAN - Ca distances of 253.5(3) pm. The Ca atoms are bridged by hexamethylenetetramine and water molecules


1989 ◽  
Vol 67 (11) ◽  
pp. 1832-1836 ◽  
Author(s):  
Frederick W. B. Einstein ◽  
Richard H. Jones ◽  
Xiaoheng Zhang ◽  
Derek Sutton

The title complex (2) has been synthesized from the reaction of (η5-C5Me5)Ir(CO)2 (1) with AgBF4. Complex 2 crystallizes in the monoclinic space group P21/c with a = 12.355(2) Å, b = 13.713(2) Å, c = 16.672(3) Å, β = 97.70(1)°, and Z = 4. The structure was solved by using 3131 observed reflections (I ≥ 2.5σ(I)) in the range 0° < 2θ < 50° to final discrepancy indices of RF = 0.032 and RwF = 0.038. The cation may be described as consisting of two molecules of 1 bound to Ag+ by donor–acceptor Ir → Ag bonds. The Ir—Ag—Ir skeleton is nearly linear (angle 173.67(6)°). The Ag—Ir bond lengths are equal (2.659(1) Å), and the two molecules of 1 are disposed mutually trans, to give the cation approximate (noncrystallographic) C2h symmetry. Keywords: complex, iridium, silver, metal-metal bond, X-ray, crystal, structure, carbonyl, donor-acceptor, pentamethylcyclopentadienyl.


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