Poly[[μ2-1,2-bis­(diphenyl­phosphan­yl)-1,2-diethylhydrazine]-μ4-nitrato-μ2-nitrato-silver(I)]

Frederik H Kriel; Manuel A Fernandes; Judy Coates

doi:10.1107/S1600536810019094

. 2010 May 26;66(Pt 6):m710. doi: 10.1107/S1600536810019094

Poly[[μ₂-1,2-bis(diphenylphosphanyl)-1,2-diethylhydrazine]-μ₄-nitrato-μ₂-nitrato-silver(I)]

Frederik H Kriel ^a,^*, Manuel A Fernandes ^b, Judy Coates ^a

PMCID: PMC2979462 PMID: 21579343

Abstract

The title compound, [Ag₂(NO₃)₂(C₂₈H₃₀N₂P₂)]_n, crystallizes in polymeric α-helices. Three O atoms from three different nitrate ions in equatorial positions and two Ag atoms at axial positions set up a trigonal bipyramid. These units are linked by the phosphine ligands into endless helical chains that run along the c axis. The crystal used for the data collection was a racemic twin.

Related literature

For related structures, see: Reddy et al. (1994 ▶, 1995 ▶); Hu (2000 ▶).

Experimental

Crystal data

[Ag₂(NO₃)₂(C₂₈H₃₀N₂P₂)]
M _r = 796.24
Orthorhombic,
a = 16.332 (1) Å
b = 20.6486 (13) Å
c = 9.0164 (5) Å
V = 3040.6 (3) Å³
Z = 4
Mo Kα radiation
μ = 1.44 mm⁻¹
T = 173 K
0.22 × 0.08 × 0.07 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: analytical (SADABS; Bruker, 1999 ▶) T _min = 0.788, T _max = 0.907
13103 measured reflections
8801 independent reflections
6217 reflections with I > 2σ(I)
R _int = 0.051

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.161
S = 1.01
8801 reflections
380 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.58 e Å⁻³
Δρ_min = −0.73 e Å⁻³
Absolute structure: Flack (1983 ▶), 3898 Friedel pairs
Flack parameter: 0.53 (4)

Data collection: SMART-NT (Bruker, 1998 ▶); cell refinement: SAINT-Plus (Bruker, 1999 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810019094/fk2018sup1.cif

e-66-0m710-sup1.cif^{(28.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810019094/fk2018Isup2.hkl

e-66-0m710-Isup2.hkl^{(421.8KB, hkl)}

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

Acknowledgments

The authors would like to thank Project AuTEK (Mintek and Harmony) and the University of the Witwatersrand for financial support.

supplementary crystallographic information

Comment

The centre of a polymeric α-helix produced by the title compound is filled by nitrate counter ions. Three oxygen atoms from three different nitrate ions occupy the equatorial positions of a trigonal bipyramid and two silver atoms are situated at the axial positions. This complex arrangement connects each silver atom of one complex to a silver atom in a neighbouring complex. The resulting α-helices (Figure 2) are packed parallel to each other and run down the c-axis of the crystal.

Polymerisation in silver nitrate complexes analogous to the title compound is commonly encountered. For example, the case of (NO₃)Ag(dppe)Ag(NO₃) that forms long chains with P—Ag—P units as the connecting entity (Hu, 2000). These long chains are also periodically connected by short chains of Ag—O—Ag bonds, giving rise to sheets of connected complexes. The Ag—P bond distances of 2.334 (2) Å and 2.349 (2) Å in the title compound are considerably shorter than those of (NO₃)Ag(dppe)Ag(NO₃) (2.41 Å and 2.42 Å). The trigonal bipyramidal structure of the title compound consists of four long Ag—O bonds in the range of 2.5 Å and two short Ag—O bonds in the range of 2.3 Å. Two longer bonds are to the same NO₃^-, while two sets of a short and long bond are connected to the other two nitrates, respectively. This compares to Ag—O bond lengths between 2.68 Å and 2.17 Å in (NO₃)Ag(dppe)Ag(NO₃). The title compound exhibits Ag—O—Ag angles in the range of 93° to 99° and O—Ag—O angles in the range of 66° to 75°.

Experimental

Silver nitrate (100 mg, 0.59 mmol) was suspended in THF or dissolved in the minimum amount of acetonitrile. To the stirred suspension were added 0.5 equivalents of bis(diphenylphosphino)-1,2-diethylhydrazine (132 mg, 0.29 mmol) in dichloromethane (DCM) (5 ml). The suspension turned light brown. The solvent was removed in vacuo to afford the product as a solid (65% yield).

The title compound crystallised from a mixture of acetonitrile, ethylacetate and hexane after being left at -20 °C for two weeks.