supplementary materials


hy2624 scheme

Acta Cryst. (2013). E69, m312    [ doi:10.1107/S1600536813012439 ]

1,1'-(Ethane-1,2-diyl)dipyridinium bis(1,2-dicyanoethene-1,2-dithiolato-[kappa]2S,S')cuprate(II)

B.-X. Hu, C.-X. Zhou, Y.-M. Liu, L.-Z. Chen and F.-M. Wang

Abstract top

In the title ion-pair complex, (C12H14N2)[Cu(C4N2S2)2], the complex anion exhibits a highly twisted coordination environment around the tetracoordinated CuII atom. The dihedral angles between the 1,2-dicyanoethene-1,2-dithiolato ligands and between the two pyridine rings in the cation are 37.49 (3) and 29.18 (10)°, respectively. Weak C-H...N and C-H...S hydrogen bonds link the cations and anions into a three-dimensional network.

Comment top

During the past few years, the molecular-based materials are widely studied due to their novel applications in the areas of materials science, medicines, biology and so on (Brammer, 2004; Robin & Fromm, 2006). Among these materials, maleonitriledithiolate (mnt) transition metal complexes are a typical kind of bis(1,2-dithiolene) complexes used as building blocks, because they possess an extended electronically delocalized core comprising a central metal, four S atoms and CC units (Duan et al., 2010; Ni et al., 2005). Studies showed that weak inter- or intramolecular interactions in the complexes could influence on their properties (Ren et al., 2006; Wang et al., 2012).

In order to know how the cations affects the stacking mode of [Cu(mnt)2]2- anion, herein, we present a new ion-pair complex. As shown in Fig. 1, it consists of one ethane-1,2-dipydinium (PyEtPy)2+ cation and a [Cu(mnt)2]2- dianion in the asymmetric unit. The [Cu(mnt)2]2- anion exhibits highly twisted coordination environment around the tetracoordinated CuII atom. The dihedral angle between the two mnt ligands is 37.49 (3)°, which is the largest value in this kind complexes. The dihedral angle between two pyridyl planes in the organic cation is 29.18 (10)°. It is seen from Table 1 and Fig. 2 that the crystal structure is stabilized by weak C—H···N and C—H···S hydrogen bonds, which link the cations and anions into a three-dimensional network.

Related literature top

For background to crystalline molecular materials and coordination polymer networks, see: Brammer (2004); Robin & Fromm (2006). For 1,2-dithiolene–metal complexes, see: Duan et al. (2010); Ni et al. (2005). For related structures, see: Ren et al. (2006); Wang et al. (2012).

Experimental top

The synthesis route of the title compound is similar to reference (Wang et al., 2012). It was prepared by a direct reaction of CuCl2 (0.171g, 1.0 mmol), Na2(mnt) (0.372g, 2.0 mmol) and ethane-1,2-dipydinium bromide (0.344g, 1.0 mmol) in a mixed solution of ethanol and H2O (v/v 1:1; 20 ml). After filtration, brown-red block-like single crystals were obtained by slow evaporation of the crude in an acetonitrile solution at room temperature in about two weeks.

Refinement top

H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.97 (methylene) and 0.93 (pyridyl) Å and with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level.
[Figure 2] Fig. 2. The packing diagram of the title compound as viewed along the a axis. Dashed lines denote hydrogen bonds.
1,1'-(Ethane-1,2-diyl)dipyridinium bis(1,2-dicyanoethene-1,2-dithiolato-κ2S,S')cuprate(II) top
Crystal data top
(C12H14N2)[Cu(C4N2S2)2]Z = 2
Mr = 530.20F(000) = 538
Triclinic, P1Dx = 1.553 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.7598 (10) ÅCell parameters from 2653 reflections
b = 12.3811 (15) Åθ = 2.2–28.0°
c = 12.6572 (16) ŵ = 1.35 mm1
α = 77.676 (2)°T = 291 K
β = 72.791 (2)°Block, brown-red
γ = 84.122 (2)°0.25 × 0.20 × 0.15 mm
V = 1133.8 (2) Å3
Data collection top
Bruker APEX CCD
diffractometer
3921 independent reflections
Radiation source: sealed tube3217 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.054
φ and ω scansθmax = 25.0°, θmin = 1.7°
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
h = 98
Tmin = 0.730, Tmax = 0.815k = 1412
5682 measured reflectionsl = 1515
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.036Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.083H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.0333P)2]
where P = (Fo2 + 2Fc2)/3
3921 reflections(Δ/σ)max < 0.001
280 parametersΔρmax = 0.39 e Å3
1 restraintΔρmin = 0.26 e Å3
Crystal data top
(C12H14N2)[Cu(C4N2S2)2]γ = 84.122 (2)°
Mr = 530.20V = 1133.8 (2) Å3
Triclinic, P1Z = 2
a = 7.7598 (10) ÅMo Kα radiation
b = 12.3811 (15) ŵ = 1.35 mm1
c = 12.6572 (16) ÅT = 291 K
α = 77.676 (2)°0.25 × 0.20 × 0.15 mm
β = 72.791 (2)°
Data collection top
Bruker APEX CCD
diffractometer
3921 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
3217 reflections with I > 2σ(I)
Tmin = 0.730, Tmax = 0.815Rint = 0.054
5682 measured reflectionsθmax = 25.0°
Refinement top
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.083Δρmax = 0.39 e Å3
S = 1.00Δρmin = 0.26 e Å3
3921 reflectionsAbsolute structure: ?
280 parametersFlack parameter: ?
1 restraintRogers parameter: ?
Special details top

Experimental. Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

6.9701 (0.0047) x + 5.1850 (0.0148) y + 7.5933 (0.0151) z = 5.1170 (0.0027)

* -0.0036 (0.0020) N5 * 0.0025 (0.0022) C9 * 0.0020 (0.0024) C10 * -0.0053 (0.0025) C11 * 0.0043 (0.0025) C12 * 0.0001 (0.0022) C13

Rms deviation of fitted atoms = 0.0034

7.3331 (0.0038) x + 4.3436 (0.0161) y + 1.7102 (0.0200) z = 4.6388 (0.0108)

Angle to previous plane (with approximate e.s.d.) = 29.18 (10)

* 0.0013 (0.0022) N6 * -0.0036 (0.0025) C16 * 0.0015 (0.0028) C17 * 0.0027 (0.0028) C18 * -0.0049 (0.0027) C19 * 0.0029 (0.0024) C20

Rms deviation of fitted atoms = 0.0031

6.9588 (0.0022) x + 3.8087 (0.0081) y - 0.7118 (0.0088) z = 7.0678 (0.0051)

Angle to previous plane (with approximate e.s.d.) = 10.99 (12)

* -0.0330 (0.0015) S1 * -0.0111 (0.0015) S2 * 0.0353 (0.0026) C1 * 0.0220 (0.0028) C4 * 0.0292 (0.0027) C2 * 0.0074 (0.0032) C3 * -0.0259 (0.0020) N1 * -0.0239 (0.0024) N2

Rms deviation of fitted atoms = 0.0252

7.2222 (0.0021) x + 4.6573 (0.0073) y + 6.9013 (0.0071) z = 8.7279 (0.0018)

Angle to previous plane (with approximate e.s.d.) = 36.27 (4)

* 0.0321 (0.0014) S3 * 0.0067 (0.0014) S4 * -0.0293 (0.0025) C5 * -0.0251 (0.0025) C7 * 0.0012 (0.0029) C8 * -0.0242 (0.0028) C6 * 0.0188 (0.0021) N3 * 0.0197 (0.0021) N4

Rms deviation of fitted atoms = 0.0220

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.7697 (4)0.4815 (2)0.1224 (2)0.0391 (7)
C20.7087 (4)0.5794 (2)0.0580 (2)0.0438 (7)
C30.7285 (5)0.5782 (3)0.2764 (3)0.0534 (9)
C40.7788 (4)0.4812 (2)0.2281 (2)0.0399 (7)
C51.0203 (4)0.0026 (2)0.1945 (2)0.0381 (7)
C61.1186 (5)0.0989 (2)0.1573 (2)0.0471 (8)
C70.9214 (4)0.0103 (2)0.3037 (2)0.0383 (7)
C80.9143 (5)0.1115 (2)0.3834 (3)0.0476 (8)
C90.4956 (4)0.0999 (2)0.1511 (2)0.0473 (8)
H9A0.51150.16260.09430.057*
C100.5896 (5)0.0029 (3)0.1309 (3)0.0597 (10)
H10A0.66950.00020.06040.072*
C110.5661 (5)0.0882 (3)0.2138 (3)0.0638 (10)
H11A0.62830.15450.20050.077*
C120.4494 (5)0.0818 (3)0.3178 (3)0.0622 (10)
H12A0.43330.14350.37590.075*
C130.3573 (5)0.0154 (2)0.3354 (3)0.0511 (8)
H13A0.27740.02000.40560.061*
C140.2858 (4)0.2108 (2)0.2732 (3)0.0413 (7)
H14A0.17530.19750.33410.050*
H14B0.25470.25060.20610.050*
C150.4079 (4)0.2779 (2)0.3040 (3)0.0453 (8)
H15A0.42960.24040.37470.054*
H15B0.52320.28380.24640.054*
C160.2857 (5)0.4217 (2)0.4142 (3)0.0525 (9)
H16A0.29960.37170.47760.063*
C170.2222 (5)0.5267 (3)0.4229 (3)0.0678 (11)
H17A0.19340.54880.49210.081*
C180.2010 (5)0.5992 (3)0.3304 (3)0.0662 (11)
H18A0.15780.67120.33590.079*
C190.2430 (5)0.5663 (3)0.2295 (3)0.0593 (10)
H19A0.22760.61500.16570.071*
C200.3078 (4)0.4609 (2)0.2238 (3)0.0506 (8)
H20A0.33840.43780.15510.061*
Cu10.88151 (5)0.23822 (3)0.20268 (3)0.03682 (13)
N10.6543 (4)0.6544 (2)0.0053 (2)0.0597 (8)
N20.6877 (5)0.6526 (2)0.3190 (3)0.0809 (11)
N31.2014 (5)0.1729 (2)0.1268 (2)0.0733 (10)
N40.9043 (5)0.1908 (2)0.4499 (2)0.0708 (9)
N50.3814 (3)0.10412 (17)0.25224 (19)0.0362 (6)
N60.3283 (3)0.39007 (18)0.31502 (19)0.0375 (6)
S10.81723 (12)0.36536 (6)0.06140 (6)0.0456 (2)
S20.84617 (12)0.36517 (6)0.31245 (6)0.0456 (2)
S31.04488 (12)0.11853 (6)0.09586 (6)0.0457 (2)
S40.80239 (11)0.10227 (6)0.35693 (6)0.0459 (2)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0419 (18)0.0328 (15)0.0380 (17)0.0020 (13)0.0092 (14)0.0017 (13)
C20.051 (2)0.0408 (17)0.0368 (17)0.0010 (15)0.0112 (15)0.0036 (14)
C30.079 (3)0.0398 (18)0.049 (2)0.0081 (17)0.0337 (19)0.0061 (16)
C40.0478 (19)0.0299 (15)0.0422 (18)0.0034 (13)0.0154 (15)0.0060 (13)
C50.0471 (19)0.0306 (15)0.0361 (17)0.0025 (13)0.0127 (14)0.0060 (12)
C60.067 (2)0.0352 (17)0.0350 (17)0.0019 (15)0.0125 (16)0.0032 (14)
C70.0486 (19)0.0275 (14)0.0375 (17)0.0017 (13)0.0135 (14)0.0018 (12)
C80.063 (2)0.0393 (18)0.0370 (18)0.0026 (15)0.0067 (16)0.0102 (15)
C90.063 (2)0.0375 (17)0.0339 (17)0.0012 (15)0.0050 (16)0.0033 (13)
C100.065 (2)0.054 (2)0.050 (2)0.0092 (18)0.0008 (18)0.0185 (18)
C110.076 (3)0.0374 (19)0.082 (3)0.0137 (18)0.026 (2)0.0213 (19)
C120.090 (3)0.0356 (18)0.059 (2)0.0010 (18)0.027 (2)0.0027 (16)
C130.069 (2)0.0411 (18)0.0373 (18)0.0007 (16)0.0114 (17)0.0022 (14)
C140.0418 (18)0.0342 (15)0.0461 (18)0.0081 (13)0.0112 (15)0.0103 (13)
C150.0436 (19)0.0362 (16)0.056 (2)0.0069 (14)0.0153 (16)0.0110 (14)
C160.079 (3)0.0449 (19)0.0355 (18)0.0065 (17)0.0199 (17)0.0051 (14)
C170.108 (3)0.050 (2)0.042 (2)0.002 (2)0.010 (2)0.0206 (17)
C180.093 (3)0.0376 (19)0.065 (3)0.0082 (19)0.017 (2)0.0171 (18)
C190.086 (3)0.0396 (19)0.052 (2)0.0044 (18)0.026 (2)0.0020 (16)
C200.071 (2)0.0458 (18)0.0339 (18)0.0015 (16)0.0114 (16)0.0099 (14)
Cu10.0427 (2)0.0313 (2)0.0346 (2)0.00331 (15)0.01034 (17)0.00546 (15)
N10.071 (2)0.0499 (17)0.0505 (18)0.0040 (15)0.0195 (16)0.0059 (14)
N20.139 (3)0.0435 (18)0.074 (2)0.0230 (19)0.053 (2)0.0209 (17)
N30.108 (3)0.0440 (17)0.058 (2)0.0173 (17)0.0132 (19)0.0122 (15)
N40.108 (3)0.0420 (17)0.0482 (18)0.0037 (17)0.0094 (18)0.0032 (15)
N50.0413 (15)0.0309 (12)0.0347 (14)0.0027 (11)0.0111 (12)0.0043 (10)
N60.0417 (15)0.0319 (13)0.0377 (14)0.0017 (11)0.0096 (12)0.0075 (11)
S10.0638 (6)0.0395 (4)0.0309 (4)0.0057 (4)0.0127 (4)0.0057 (3)
S20.0669 (6)0.0341 (4)0.0418 (5)0.0090 (4)0.0272 (4)0.0091 (3)
S30.0639 (6)0.0335 (4)0.0312 (4)0.0070 (4)0.0053 (4)0.0034 (3)
S40.0571 (5)0.0370 (4)0.0342 (4)0.0031 (4)0.0018 (4)0.0046 (3)
Geometric parameters (Å, º) top
C1—C41.360 (4)C13—H13A0.9300
C1—C21.431 (4)C14—N51.482 (3)
C1—S11.730 (3)C14—C151.503 (4)
C2—N11.143 (3)C14—H14A0.9700
C3—N21.136 (4)C14—H14B0.9700
C3—C41.430 (4)C15—N61.479 (3)
C4—S21.732 (3)C15—H15A0.9700
C5—C71.357 (4)C15—H15B0.9700
C5—C61.437 (4)C16—N61.333 (3)
C5—S31.721 (3)C16—C171.357 (4)
C6—N31.134 (3)C16—H16A0.9300
C7—C81.425 (4)C17—C181.356 (4)
C7—S41.738 (3)C17—H17A0.9300
C8—N41.141 (4)C18—C191.361 (4)
C9—N51.332 (4)C18—H18A0.9300
C9—C101.371 (4)C19—C201.358 (4)
C9—H9A0.9300C19—H19A0.9300
C10—C111.353 (5)C20—N61.332 (4)
C10—H10A0.9300C20—H20A0.9300
C11—C121.373 (5)Cu1—S32.2554 (8)
C11—H11A0.9300Cu1—S12.2561 (8)
C12—C131.361 (4)Cu1—S22.2571 (8)
C12—H12A0.9300Cu1—S42.2630 (8)
C13—N51.335 (4)
C4—C1—C2120.1 (2)N6—C15—C14111.5 (2)
C4—C1—S1123.3 (2)N6—C15—H15A109.3
C2—C1—S1116.5 (2)C14—C15—H15A109.3
N1—C2—C1176.5 (3)N6—C15—H15B109.3
N2—C3—C4177.2 (3)C14—C15—H15B109.3
C1—C4—C3120.8 (2)H15A—C15—H15B108.0
C1—C4—S2122.9 (2)N6—C16—C17120.2 (3)
C3—C4—S2116.3 (2)N6—C16—H16A119.9
C7—C5—C6119.5 (2)C17—C16—H16A119.9
C7—C5—S3124.0 (2)C18—C17—C16119.7 (3)
C6—C5—S3116.5 (2)C18—C17—H17A120.1
N3—C6—C5177.7 (4)C16—C17—H17A120.1
C5—C7—C8121.6 (2)C17—C18—C19119.9 (3)
C5—C7—S4122.7 (2)C17—C18—H18A120.1
C8—C7—S4115.7 (2)C19—C18—H18A120.1
N4—C8—C7177.6 (3)C20—C19—C18118.7 (3)
N5—C9—C10119.9 (3)C20—C19—H19A120.6
N5—C9—H9A120.0C18—C19—H19A120.6
C10—C9—H9A120.0N6—C20—C19121.1 (3)
C11—C10—C9119.9 (3)N6—C20—H20A119.4
C11—C10—H10A120.1C19—C20—H20A119.4
C9—C10—H10A120.1S3—Cu1—S197.08 (3)
C10—C11—C12119.3 (3)S3—Cu1—S2153.90 (4)
C10—C11—H11A120.4S1—Cu1—S292.15 (3)
C12—C11—H11A120.4S3—Cu1—S492.28 (3)
C13—C12—C11119.6 (3)S1—Cu1—S4152.11 (4)
C13—C12—H12A120.2S2—Cu1—S490.80 (3)
C11—C12—H12A120.2C9—N5—C13121.1 (2)
N5—C13—C12120.2 (3)C9—N5—C14119.0 (2)
N5—C13—H13A119.9C13—N5—C14119.9 (2)
C12—C13—H13A119.9C20—N6—C16120.3 (2)
N5—C14—C15108.6 (2)C20—N6—C15119.3 (2)
N5—C14—H14A110.0C16—N6—C15120.2 (2)
C15—C14—H14A110.0C1—S1—Cu1100.72 (10)
N5—C14—H14B110.0C4—S2—Cu1100.81 (9)
C15—C14—H14B110.0C5—S3—Cu1100.54 (9)
H14A—C14—H14B108.4C7—S4—Cu1100.40 (10)
C2—C1—C4—C30.3 (5)C17—C16—N6—C200.4 (5)
S1—C1—C4—C3176.6 (3)C17—C16—N6—C15176.2 (3)
C2—C1—C4—S2178.5 (2)C14—C15—N6—C2067.1 (4)
S1—C1—C4—S22.1 (4)C14—C15—N6—C16116.2 (3)
C6—C5—C7—C80.8 (5)C4—C1—S1—Cu11.0 (3)
S3—C5—C7—C8176.3 (2)C2—C1—S1—Cu1175.5 (2)
C6—C5—C7—S4178.5 (2)S3—Cu1—S1—C1158.09 (11)
S3—C5—C7—S41.4 (4)S2—Cu1—S1—C12.55 (11)
N5—C9—C10—C110.0 (5)S4—Cu1—S1—C193.23 (12)
C9—C10—C11—C120.8 (5)C1—C4—S2—Cu13.9 (3)
C10—C11—C12—C131.0 (6)C3—C4—S2—Cu1174.9 (2)
C11—C12—C13—N50.5 (5)S3—Cu1—S2—C4114.23 (12)
N5—C14—C15—N6174.3 (2)S1—Cu1—S2—C43.32 (11)
N6—C16—C17—C180.4 (6)S4—Cu1—S2—C4148.94 (11)
C16—C17—C18—C190.2 (6)C7—C5—S3—Cu11.0 (3)
C17—C18—C19—C200.8 (6)C6—C5—S3—Cu1176.2 (2)
C18—C19—C20—N60.8 (6)S1—Cu1—S3—C5155.81 (11)
C10—C9—N5—C130.5 (5)S2—Cu1—S3—C594.35 (12)
C10—C9—N5—C14178.0 (3)S4—Cu1—S3—C52.14 (11)
C12—C13—N5—C90.3 (5)C5—C7—S4—Cu12.9 (3)
C12—C13—N5—C14177.7 (3)C8—C7—S4—Cu1174.9 (2)
C15—C14—N5—C983.5 (3)S3—Cu1—S4—C72.65 (11)
C15—C14—N5—C1394.0 (3)S1—Cu1—S4—C7112.46 (11)
C19—C20—N6—C160.2 (5)S2—Cu1—S4—C7151.43 (10)
C19—C20—N6—C15176.9 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C11—H11A···N2i0.932.613.356 (4)137
C14—H14A···N4ii0.972.603.341 (4)133
C14—H14B···N1iii0.972.603.479 (4)151
C15—H15B···S10.972.833.769 (3)163
C16—H16A···N2iv0.932.563.368 (4)146
C17—H17A···S2iv0.932.823.743 (3)171
C19—H19A···N3v0.932.563.235 (4)129
C20—H20A···N1iii0.932.523.422 (4)164
Symmetry codes: (i) x, y1, z; (ii) x+1, y, z+1; (iii) x+1, y+1, z; (iv) x+1, y+1, z+1; (v) x1, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C11—H11A···N2i0.932.613.356 (4)137
C14—H14A···N4ii0.972.603.341 (4)133
C14—H14B···N1iii0.972.603.479 (4)151
C15—H15B···S10.972.833.769 (3)163
C16—H16A···N2iv0.932.563.368 (4)146
C17—H17A···S2iv0.932.823.743 (3)171
C19—H19A···N3v0.932.563.235 (4)129
C20—H20A···N1iii0.932.523.422 (4)164
Symmetry codes: (i) x, y1, z; (ii) x+1, y, z+1; (iii) x+1, y+1, z; (iv) x+1, y+1, z+1; (v) x1, y+1, z.
Acknowledgements top

This work was supported by the National Natural Science Foundation of China for Young Scholars (grant No. 21201087), the Natural Science Foundation of Jiangsu Provincial Department of Education (grant No. 11KJB150004), the Science and Technology Project of the State General Administration of Quality Supervision, Inspection and Quarantine, People's Republic of China (grant Nos. 2011QK121 and 2011QK122) and a start-up grant from Jiangsu University of Science and Technology.

references
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