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Acta Crystallogr Sect E Struct Rep Online. 2010 December 1; 66(Pt 12): m1555–m1556.
Published online 2010 November 13. doi:  10.1107/S1600536810044703
PMCID: PMC3011467

Poly[μ-bromido-μ-(2,2-dimethyl­propane-1,3-diyl diisocyanide)-silver(I)]: a powder diffraction study


In the title compound, [AgBr(C7H10N2)]n, adjacent Ag(I) atoms are bridged by bidentate CNCH2C(CH3)2CH2NC ligands via the NC groups, forming [Ag{CNCH2C(CH3)2CH2NC}]n chains with the metal atom in a distorted tetrahedral coordination. The bromide counter-anions cross-link the Ag(I) atoms of the chains, forming a two-dimensional polymeric network {[AgI(CNCH2C(CH3)2CH2NC)]Br}n extend­ing parallel to (010). The polymeric structure is similar to that of the very recently reported Cl, I and NO3 analogues. This gives a strong indication that 2,2-dimethyl­propane-1,3-diyl diisocyanide is a potential ligand for giving polymeric structures on treatment with AgX (X = Cl, Br, I or NO3 ) regardless of the counter-anion used.

Related literature

For the preparation of the bidentate ligand CNCH2C(CH3)2CH2NC, see: Al-Ktaifani et al. (2008 [triangle]). For similar polymeric structures, see: Al-Ktaifani et al. (2008 [triangle]); Rukiah & Al-Ktaifani (2008 [triangle], 2009 [triangle]). For disocyano ligands and their coordination complexes, see: Harvey (2001 [triangle]); Sakata et al. (2003 [triangle]); Espinet et al. (2000 [triangle]); Moigno et al. (2002 [triangle]). For chelate complexing, see: Chemin et al. (1996 [triangle]). Pseudo-Voigt profile coefficients as parameterized in Thompson et al. (1987 [triangle]). Asymmetry correction of Finger et al. (1994 [triangle]). Microstrain broadening by Stephens (1999 [triangle]). Indexing was performed using the program DICVOL04 (Boultif & Louër, 2004 [triangle]). The best estimated space group was determined with the help of the program Check Group inter­faced by WinPLOTR (Roisnel & Rodriguez-Carvajal, 2001 [triangle]). The powder diffraction pattern was subsequently refined using the LeBail method by the program FULLPROF (Rodriguez-Carvajal, 2001 [triangle]). The program GSAS (Larson & Von Dreele, 2004 [triangle]) was inter­faced by EXPGUI (Toby, 2001 [triangle]). The preferred orientation was modeled using a spherical-harmonics description (Von Dreele, 1997 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-m1555-scheme1.jpg


Crystal data

  • [AgBr(C7H10N2)]
  • M r = 309.94
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-m1555-efi1.jpg
  • a = 16.24649 (13) Å
  • b = 16.59379 (12) Å
  • c = 7.40433 (4) Å
  • V = 1996.14 (2) Å3
  • Z = 8
  • Cu Kα1 radiation, λ = 1.54060 Å
  • μ = 20.43 mm−1
  • T = 298 K
  • flat sheet, 7.0 × 7.0 mm

Data collection

  • STOE STADI P Transmission diffractometer
  • Specimen mounting: drifted powder between two Mylar foils
  • Data collection mode: transmission
  • Scan method: step
  • Absorption correction: for a cylinder mounted on the ϕ axis function for a flat sample in transmission geometry (GSAS; Larson & Von Dreele, 2004 [triangle]) T min = 0.139, T max = 0.192
  • min = 4.97°, 2θmax = 89.95°, 2θstep = 0.02°


  • R p = 0.020
  • R wp = 0.027
  • R exp = 0.021
  • R(F 2) = 0.019
  • χ2 = 1.638
  • 4250 data points
  • 172 parameters
  • 40 restraints
  • H-atom parameters constrained

Data collection: WinXPOW (Stoe & Cie, 1999 [triangle]); cell refinement: GSAS (Larson & Von Dreele, 2004 [triangle]); data reduction: WinXPOW; program(s) used to solve structure: FOX (Favre-Nicolin & Černý, 2002 [triangle]); program(s) used to refine structure: GSAS (Larson & Von Dreele, 2004 [triangle]); molecular graphics: ORTEP-3 (Farrugia, 1997 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2010 [triangle]).

Table 1
Selected geometric parameters (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810044703/er2080sup1.cif

Rietveld powder data: contains datablocks I. DOI: 10.1107/S1600536810044703/er2080Isup2.rtv

Additional supplementary materials: crystallographic information; 3D view; checkCIF report


The authors thank Professors I. Othman, Director General, and T. Yassine, Head of the Chemistry Department, for their support and encouragement.

supplementary crystallographic information


In order to better understand and further explore the chemistry of 2,2-dimethylpropane-1,3-diyl diisocyanide, the synthesis and solid state characterization of the polymeric complex {[AgI(CNCH2C(CH3)2CH2NC)]Br}n is presented. Treatment of AgBr with two equimolar amount of 2,2-dimethylpropane-1,3-diyl diisocyanide in dry EtOH at room temperature afforded a highly insoluble white powder (I) even in polar or coordinate solvents. These strongly gave an indication that the obtained compound (I) have a polymeric structure, which is very similar to the polymeric structure of {[AgI(CNCH2C(CH3)2CH2NC)]X}n (X = Cl- or I-) (Al-Ktaifani et al., 2008; Rukiah & Al-Ktaifani, 2009).

The solid state structure of (I) was confirmed by X-ray powder diffraction study exhibiting, as expected, a polymeric structure, which is very similar to the analogous Cl-, I- and NO3- polymers. In the obtained structure, the AgI centers are bridged with each of the two adjacent Ag neighbours by the bidentate ligands CNCH2C(CH3)2CH2NC via the NC groups to form {AgI(CNCH2C(CH3)2CH2NC)}n chains. The Br- counterpart anions are cross linked the Ag centres of the chains to form a polymeric 2-D network {[AgI(CNCH2C(CH3)2CH2NC)]Br}n (Fig. 1). In the same manner to the polymeric structure of Cl-, I- and NO3- analogues, the CNCH2C(CH3)2CH2NC in the complex just behaves as bis-monodentate and the chelate behaviour is completely absent. This is undoubtedly expected for steric reason as the distance between the two isocyanide groups in the CNCH2C(CH3)2CH2NC molecule are relatively too short to allow chelate complexing (Chemin et al., 1996) (Fig.2).

As the conformation of the bidentate ligand (CNCH2C(CH3)2CH2NC) in the three polymeric structures are almost alike, it can be concluded that their molecular structures are very similar. Therefore it can be stated the counterpart anion (Cl-, Br- or I-) have no effective role in changing the polymeric structure of the complex. It is also noteworthy, that the bidentate ligand exhibits a very strong tendency to form polymeric complexes rather than dimeric or trimeric complexes suggesting the 2,2-dimethylpropane-1,3-diyl diisocyanide to be a potential bidentate ligand in the syntheses of organometallic polymers of different transition metals.


All reactions and manipulations were carried out under inert atmosphere by using two fold vacuum line and schlenk technique. Solvents were dried and distilled over sodium wire; glassware dried and flamed before used. AgBr was a commercial sample and was used as received. IR spectra were operated on FTIR Jasco 300 E. Microanalysis was performed using EURO EA. Powder X-ray diffraction was performed by Stoe Transmission diffractometre (Stadi P).

A solution of CNCH2C(CH3)2CH2NC (0.30 g, 2.45 mmol) in EtOH (5 ml) was added to a suspension of AgBr (0.22 g, 1.19 mmol) in dry EtOH (10 ml) at room temperature. The resulting solution was stirred for overnight, and then filtered and volatiles were removed in vacuo. The obtained product was washed with ether to afford a white powder (0.29 g, yield 80%, m.p. starts to decompose at 395 K). Analytical data for AgC7H10N2Br: found C, 27.95%; H, 3.35%; N, 7.99%; required: C, 27.12%; H, 3.25%; N, 9.03%. IR (KBr) νcm-1: 2201.6 (N[equivalent] C).


The powder sample was slightly ground in a mortar, loaded into two foils of Mylar and fixed in the sample holder with a mask of suitable internal diameter (7.0 mm). Data were collected at room temperature and pressure in transmission geometry employing Cu Kα1 radiation. Indexing was performed using the program DICVOL04 (Boultif & Louër, 2004) with default options. An orthorhombic unit cell of reasonable volume (assuming Z=8) gave indexing figures of merit M20=18.0, F20=36.9(0.0090, 60). The best estimated space group in the orthorhombic system was Pcab which determined with the help of the program Check Group interfaced by WinPLOTR (Roisnel & Rodriguez-Carvajal, 2001). The parameters a and b were interchanged for working with the standard setting of space group i.e Pbca. The powder diffraction pattern from 5 to 90° (2q) was subsequently refined with these cell and space group using LeBail method by the program FULLPROF (Rodriguez-Carvajal, 2001). One line with very low intensity was not indexed with the previous cell and corresponds to the reflection (111) of the AgBr. The program FOX (Favre-Nicolin & Černý, 2002) was employed for structure solution. The powder pattern was truncated to 55° in 2θ (Cu Kα1 ), corresponding to real-space resolution of 1.67 Å. The Monte Carlo simulated annealing (parallel tempering algorithm) used to solve the crystal structure of compound (I) from powder pattern in direct space. One molecule of CNCH2C(CH3)2CH2NC ligand and two free atoms of Ag and Br were introduced randomly in the orthorhombic cell calculated by Le Bail refinement. The H atoms can be ignored during the structure solution process because they do not contribute significantly to the powder diffraction pattern, due to their low X-ray scattering power. During the parallel tempering calculations, the ligand had the possibility to translate, to rotate around its centre of mass and to modify its torsion angles and the atoms Ag and Br had the possibility to modify its position in the unit cell. The model found by FOX was introduced in the program GSAS (Larson & Von Dreele, 2004), interfaced by EXPGUI (Toby, 2001) for Rietveld refinements as a starting point. The background was refined using a shifted Chebyshev polynomial with 20 coefficients. The Thompson-Cox-Hastings (Thompson et al., 1987) pseudo-Voigt profile function was used with an axial divergence asymmetry correction of (Finger et al., 1994). The two asymmetry parameters of this function S/L and D/L were both fixed at 0.0215 during the Rietveld refinement.

Geometric soft restraints were applied to the C°N, N—C and C—C distances to guide them towards their normal values, but no restrains were imposed on the Ag—C and Ag—Br distances. Likewise, no restraints were imposed on bond angles. The hydrogen atoms were introduced at theoretical positions with CH2 and CH3 distances constrained to be 0.97 Å for CH3 and 0.98 Å for CH2. They were refined with restrains on their bonds distances and bond angles to their normal values. One isotropic atomic displacement parameter was introduced per types of atoms C, N and H. The final refinement cycles were performed using anisotropic displacement parameters for Ag and Br atoms. Intensities were corrected for absorption effects with a function for a flat plate sample in transmission geometry (function number 4 in GSAS). The value of with m.d was 0.8. The plate normal can be either perpendicular to the diffraction vector or tilted by some fixed angle [var phi] in the diffraction plane. The preferred orientation was modeled using a spherical-harmonics description (Von Dreele, 1997) with 18 coefficients. In the course of the refinement, the structure of AgBr has been introduced in the final refinement. The unit-cell parameters, the atomic displacement parameters of Ag and Br and the profile parameters were allowed to vary of this compound. The amount of this impurity was about 0.1%. The observed and calculated diffraction patterns for the refined crystal structure are shown in Fig. 3.


Fig. 1.
A view, along the c axis of the crystal structure of compound (I), H atoms are not shown for clarity.
Fig. 2.
The asymmetric unit of (I) and atom-numbering are shown.
Fig. 3.
Final observed (points), calculated (line) and difference profiles for the Rietveled refinement of (I).

Crystal data

[AgBr(C7H10N2)]F(000) = 1184.0
Mr = 309.94Dx = 2.063 Mg m3
Orthorhombic, PbcaCu Kα1 radiation, λ = 1.54060 Å
Hall symbol: -P 2ac 2abµ = 20.43 mm1
a = 16.24649 (13) ÅT = 298 K
b = 16.59379 (12) ÅParticle morphology: fine powder visual estimate
c = 7.40433 (4) ÅWhite
V = 1996.14 (2) Å3flat sheet, 7.0 × 7.0 mm
Z = 8Specimen preparation: Prepared at 298 K and 101.3 kPa

Data collection

STOE STADI P Transmission diffractometerScan method: step
Radiation source: sealed X-ray tube, C-TechAbsorption correction: for a cylinder mounted on the [var phi] axis function for a flat plate sample in transmission geometry absorption correction 'GSAS (Larson & Von Dreele, 2004)'
Ge 111Tmin = 0.139, Tmax = 0.192
Specimen mounting: drifted powder between two Mylar foilsmin = 4.97°, 2θmax = 89.95°, 2θstep = 0.02°
Data collection mode: transmission


Least-squares matrix: fullExcluded region(s): none
Rp = 0.020172 parameters
Rwp = 0.02740 restraints
Rexp = 0.021H-atom parameters constrained
R(F2) = 0.01907(Δ/σ)max = 0.02
χ2 = 1.638Background function: GSAS Background function number 1 with 20 terms. Shifted Chebyshev function of 1st kind 1: 1519.26 2: -1446.56 3: 737.807 4: -254.400 5: 19.2069 6: 34.2759 7: -57.6962 8: 44.0465 9: 4.23667 10: 15.2262 11: -36.4418 12: 19.8416 13: 11.6080 14: -21.7772 15: 7.42188 16: 2.13196 17: -8.09916 18: 10.4475 19: -3.62142 20: 2.86699
4250 data pointsPreferred orientation correction: Spherical harmonics function

Special details

Experimental. The sample was ground lightly in a mortar, loaded between two Myler foils and fixed in the sample holder with a mask of 7.0 mm intrnal diameter.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

Ag10.38967 (9)0.80095 (7)0.4117 (2)0.05958
Br10.30684 (11)0.82642 (9)0.0900 (3)0.06015
C10.5098 (7)0.7575 (9)0.344 (2)0.057 (2)*
C20.6370 (3)0.6752 (3)0.2513 (6)0.057 (2)*
C30.6320 (4)0.5873 (3)0.3162 (7)0.057 (2)*
C40.5598 (2)0.5488 (2)0.2127 (5)0.057 (2)*
C50.6150 (2)0.5772 (2)0.5193 (5)0.057 (2)*
C60.7112 (3)0.5453 (3)0.2551 (6)0.057 (2)*
C70.8331 (7)0.6053 (8)0.4282 (19)0.057 (2)*
N10.5660 (5)0.7181 (6)0.3133 (11)0.044 (3)*
N20.7802 (6)0.5754 (5)0.3512 (12)0.044 (3)*

Atomic displacement parameters (Å2)

Ag10.0490 (14)0.0637 (13)0.0660 (12)0.0106 (10)0.0053 (16)−0.0066 (11)
Br10.079 (2)0.0452 (15)0.0560 (16)0.0074 (12)−0.011 (2)0.0034 (14)

Geometric parameters (Å, °)

Ag1—Br12.7680 (19)C3—C51.538 (5)
Ag1—Br1i2.8322 (22)C3—C61.533 (5)
Ag1—C12.140 (9)C4—H4a0.97
Ag1—C7ii2.162 (10)C4—H4b0.97
Br1—Ag12.7680 (19)C4—H4c0.97
Br1—Ag1iii2.8322 (22)C5—H5a0.97
C1—N11.146 (16)C5—H5b0.97
C2—C31.538 (5)C5—H5c0.97
C2—N11.431 (5)C6—H6a0.98
C2—H2b0.98C7—Ag1iv2.162 (10)
C3—C41.540 (5)C7—N21.144 (16)
Br1—Ag1—Br1i106.50 (7)C3—C4—H4b109.3
Br1—Ag1—C1107.1 (4)C3—C4—H4c109.5
Br1—Ag1—C7v98.9 (4)H4a—C4—H4b109.5
Br1i—Ag1—C1106.9 (4)H4a—C4—H4c109.4
Br1i—Ag1—C7v94.55 (35)H4b—C4—H4c109.4
C1—Ag1—C7v139.3 (6)C3—C5—H5a109.4
Ag1—Br1—Ag1iii93.22 (6)C3—C5—H5b109.4
Ag1—C1—N1164.9 (14)C3—C5—H5c109.4
C3—C2—N1109.2 (6)H5a—C5—H5b109.5
N1—C2—H2a109.5C3—C6—N2110.8 (6)
C2—C3—C4106.1 (4)N2—C6—H6a109.1
C2—C3—C5114.7 (4)N2—C6—H6b109.1
C2—C3—C6107.1 (4)H6a—C6—H6b109.3
C4—C3—C5107.76 (35)Ag1vi—C7—N2154.8 (13)
C4—C3—C6107.7 (4)C1—N1—C2171.9 (13)
C5—C3—C6113.0 (4)C6—N2—C7174.9 (13)
C1—Ag1—Br1—Ag1iii31.9 (5)N1—C2—C3—C468.0 (13)
C7ii—Ag1—Br1—Ag1iii−179.7 (4)N1—C2—C3—C5−50.8 (14)
Br1i—Ag1—Br1—Ag1iii−82.21 (8)N1—C2—C3—C6−177.1 (10)
Br1—Ag1—C7ii—N2ii70 (3)C2—C3—C6—N268.7 (13)
C1—Ag1—C7ii—N2ii−160 (3)C4—C3—C6—N2−177.4 (10)
Br1—Ag1—Br1i—Ag1i−168.31 (7)C5—C3—C6—N2−58.6 (14)
C1—Ag1—Br1i—Ag1i77.5 (4)

Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) x−1/2, −y+3/2, −z+1; (iii) x, −y+3/2, z−1/2; (iv) x+1/2, −y+3/2, −z+1; (v) x+1/2, −y+5/2, −z+1; (vi) x+3/2, −y+5/2, −z+1.

Hydrogen-bond geometry (Å, °)

C2—H2A···N20.982.602.950 (17)101.0
C4—H4C···N10.972.452.908 (18)108.0
C5—H5A···N20.972.622.959 (18)101.0
C5—H5B···N10.972.532.903 (16)103.0
C6—H6A···Br1vii0.982.853.820 (13)169.0
C6—H6B···Br1viii0.982.913.671 (13)136.0

Symmetry codes: (vii) x+1/2, −y+3/2, −z; (viii) −x+1, y−1/2, −z+1/2.


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ER2080).


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