Low-dimensional compounds containing cyanido groups. Part XXXV. Structure, spectral, thermal and magnetic properties of a binuclear Cu^II–bi­quinoline complex with bridging and terminal dicyanamide ligands

From the system CuCl₂–biq–NaN(CN)₂ (biq is 2,2′-bi­quinoline), the binuclear mol­ecular complex bis­(μ-dicyanamido-κ²N¹:N⁵)bis­[(2,2′-bi­quinoline-κ²N,N′)(di­cyanamido-κN¹)copper(II)], [Cu₂(C₂N₃)₄(C₁₈H₁₂N₂)₂] or [Cu₂(biq)₂(dca)₂(μ_1,5-dca)₂] (1) [dca is dicyanamide, N(CN)₂⁻] was isolated and characterized by crystal structure analysis, and spectral, thermal and magnetic measurements. IR spectroscopy confirmed the presence of the biq and dca ligands in 1. Its solid-state structure consists of discrete centrosymmetric binuclear copper(II) units with double end-to-end dca bridges. Each Cu^II atom is in a distorted square-pyramidal environment with the equatorial plane formed by two nitrile N atoms from bridging dca groups, one of the two N atoms of the chelate biq mol­ecule and one nitrile N atom from a terminal dca ligand, whereas the second biq N atom occupies the axial position. Thermal decomposition of 1 in an air atmosphere proceeds gradually, with copper(I) cyanide being the final decomposition product. Magnetic measurements revealed the formation of alternating spin chains and a relatively strong exchange inter­action within the binuclear units was also confirmed by Broken Symmetry DFT (density functional theory) calculations.

Computing details

Data collection: CrysAlis PRO (Rigaku OD, 2017); cell refinement: CrysAlis PRO (Rigaku OD, 2017); data reduction: CrysAlis PRO (Rigaku OD, 2017); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009).

Bis(µ-dicyanamido-κ²N¹:N⁵)bis[(2,2'-biquinoline-κ²N,N')(dicyanamido-κN¹)copper(II)]

Crystal data

[Cu2(C2N3)4(C18H12N2)2]	Z = 1
Mr = 903.87	F(000) = 458
Triclinic, P1	Dx = 1.575 Mg m^−3
a = 9.5158 (5) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.6393 (4) Å	Cell parameters from 7968 reflections
c = 11.0824 (7) Å	θ = 4.3–29.1°
α = 88.441 (4)°	µ = 1.18 mm^−1
β = 71.611 (5)°	T = 120 K
γ = 81.106 (4)°	Prism, blue
V = 952.78 (9) Å^3	0.33 × 0.24 × 0.13 mm

Data collection

Rigaku Xcalibur AtlasS2 Gemini ultra diffractometer	4642 independent reflections
Radiation source: fine-focus sealed X-ray tube	4219 reflections with I > 2σ(I)
Detector resolution: 5.1783 pixels mm^-1	Rint = 0.025
ω scans	θmax = 29.4°, θmin = 3.4°
Absorption correction: multi-scan (CrysAlis PRO; Rigaku OD, 2017)	h = −12→12
Tmin = 0.804, Tmax = 1.000	k = −12→12
14202 measured reflections	l = −15→13

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.035	H-atom parameters constrained
wR(F^2) = 0.095	w = 1/[σ^2(Fo^2) + (0.0438P)^2 + 0.8125P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.001
4642 reflections	Δρmax = 1.09 e Å^−3
280 parameters	Δρmin = −0.35 e Å^−3

Special details

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

Refinement. Crystal structure of 1 was determined using an Oxford Diffraction Xcalibur Gemini ultra diffractometer equipped with an AtlasS2 CCD detector using MoKα radiation. CrysAlis PRO 1.171.39.35c (Rigaku Oxford Diffraction, 2017) was used for data collection, cell refinement, data reduction and absorption correction. The structure was solved by SHELXT (Sheldrick, 2015a) and subsequent Fourier syntheses using SHELXL2014 (Sheldrick, 2015b), implemented in WinGX program suite (Farrugia, 2012). Anisotropic displacement parameters were refined for all non-H atoms. An analysis of the bond lengths and angles was performed using SHELXL2014 while PLATON (Spek, 2009) running under WinGX was used to analyze the π–π interactions. DIAMOND (Brandenburg, 2009) was used for molecular graphics.

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

	x	y	z	Uiso*/Ueq
Cu1	0.30516 (3)	0.25748 (2)	0.24715 (2)	0.01807 (9)
N10	0.11429 (19)	0.39324 (17)	0.27427 (16)	0.0183 (3)
N20	0.15998 (18)	0.18501 (17)	0.42799 (15)	0.0181 (3)
N2	0.5031 (2)	0.1424 (2)	0.18965 (17)	0.0258 (4)
N3	0.7546 (2)	−0.1474 (2)	−0.12686 (17)	0.0262 (4)
N1	0.7337 (2)	0.0036 (2)	0.05344 (18)	0.0263 (4)
N5	0.3950 (2)	0.4106 (2)	0.3069 (2)	0.0322 (4)
C21	0.0269 (2)	0.2656 (2)	0.46555 (18)	0.0189 (4)
C11	−0.0001 (2)	0.3787 (2)	0.37726 (18)	0.0189 (4)
C2	0.6072 (2)	0.0757 (2)	0.12148 (19)	0.0202 (4)
C3	0.7361 (2)	−0.0747 (2)	−0.04102 (19)	0.0201 (4)
C22	0.1892 (2)	0.0761 (2)	0.50342 (19)	0.0202 (4)
C12	0.0987 (2)	0.4946 (2)	0.18738 (19)	0.0215 (4)
C27	0.0820 (2)	0.0500 (2)	0.62095 (19)	0.0232 (4)
C19	−0.1403 (2)	0.4656 (2)	0.4009 (2)	0.0261 (4)
H19	−0.2208	0.4539	0.4753	0.031*
C23	0.3281 (2)	−0.0141 (2)	0.4617 (2)	0.0253 (4)
H23	0.4002	0.0018	0.3831	0.030*
C29	−0.0855 (2)	0.2457 (2)	0.58108 (19)	0.0239 (4)
H29	−0.1794	0.3057	0.6048	0.029*
C5	0.4456 (2)	0.5057 (3)	0.2812 (2)	0.0321 (5)
C18	−0.1592 (3)	0.5664 (2)	0.3162 (2)	0.0290 (5)
H18	−0.2535	0.6246	0.3313	0.035*
C28	−0.0571 (3)	0.1391 (2)	0.6580 (2)	0.0270 (5)
H28	−0.1309	0.1251	0.7363	0.032*
C25	0.2529 (3)	−0.1502 (3)	0.6520 (2)	0.0312 (5)
H25	0.2758	−0.2272	0.7015	0.037*
C17	−0.0394 (3)	0.5846 (2)	0.2065 (2)	0.0253 (4)
C24	0.3588 (3)	−0.1248 (2)	0.5349 (2)	0.0292 (5)
H24	0.4524	−0.1849	0.5064	0.035*
C26	0.1182 (3)	−0.0651 (3)	0.6943 (2)	0.0301 (5)
H26	0.0479	−0.0828	0.7735	0.036*
C13	0.2216 (3)	0.5100 (2)	0.0788 (2)	0.0288 (5)
H13	0.3139	0.4485	0.0640	0.035*
C14	0.2069 (3)	0.6144 (3)	−0.0051 (2)	0.0380 (6)
H14	0.2902	0.6259	−0.0773	0.046*
N6	0.4470 (3)	0.8162 (3)	0.1354 (3)	0.0546 (7)
C16	−0.0506 (3)	0.6896 (3)	0.1163 (3)	0.0368 (6)
H16	−0.1430	0.7498	0.1274	0.044*
C6	0.4737 (3)	0.7222 (3)	0.1928 (3)	0.0401 (6)
C15	0.0702 (3)	0.7045 (3)	0.0143 (3)	0.0425 (6)
H15	0.0623	0.7764	−0.0445	0.051*
N4	0.5117 (4)	0.6184 (3)	0.2628 (4)	0.0712 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.01698 (13)	0.01921 (13)	0.01593 (13)	0.00010 (9)	−0.00346 (9)	−0.00140 (9)
N10	0.0193 (8)	0.0174 (8)	0.0186 (8)	−0.0015 (6)	−0.0071 (6)	−0.0015 (6)
N20	0.0182 (8)	0.0202 (8)	0.0169 (8)	−0.0046 (6)	−0.0062 (6)	−0.0003 (6)
N2	0.0233 (9)	0.0301 (10)	0.0240 (9)	0.0018 (7)	−0.0093 (7)	−0.0069 (7)
N3	0.0213 (9)	0.0310 (10)	0.0245 (9)	0.0022 (7)	−0.0068 (7)	−0.0080 (7)
N1	0.0181 (8)	0.0329 (10)	0.0278 (9)	0.0017 (7)	−0.0088 (7)	−0.0116 (7)
N5	0.0286 (10)	0.0278 (10)	0.0353 (11)	0.0072 (8)	−0.0080 (8)	−0.0056 (8)
C21	0.0196 (9)	0.0215 (9)	0.0169 (9)	−0.0055 (7)	−0.0063 (7)	−0.0026 (7)
C11	0.0186 (9)	0.0201 (9)	0.0185 (9)	−0.0026 (7)	−0.0062 (7)	−0.0042 (7)
C2	0.0203 (10)	0.0222 (10)	0.0202 (9)	−0.0021 (8)	−0.0099 (8)	−0.0018 (7)
C3	0.0136 (9)	0.0214 (9)	0.0236 (10)	0.0004 (7)	−0.0051 (7)	0.0011 (8)
C22	0.0224 (10)	0.0227 (10)	0.0202 (9)	−0.0085 (8)	−0.0110 (8)	0.0022 (7)
C12	0.0273 (11)	0.0182 (9)	0.0223 (10)	−0.0036 (8)	−0.0122 (8)	0.0001 (7)
C27	0.0277 (11)	0.0286 (11)	0.0184 (10)	−0.0115 (9)	−0.0115 (8)	0.0026 (8)
C19	0.0187 (10)	0.0303 (11)	0.0271 (11)	−0.0002 (8)	−0.0053 (8)	−0.0042 (8)
C23	0.0245 (11)	0.0265 (11)	0.0277 (11)	−0.0066 (8)	−0.0114 (9)	0.0045 (8)
C29	0.0196 (10)	0.0315 (11)	0.0192 (10)	−0.0054 (8)	−0.0030 (8)	−0.0034 (8)
C5	0.0175 (10)	0.0344 (13)	0.0450 (14)	0.0022 (9)	−0.0125 (10)	−0.0112 (10)
C18	0.0231 (11)	0.0268 (11)	0.0382 (13)	0.0042 (8)	−0.0147 (9)	−0.0040 (9)
C28	0.0269 (11)	0.0375 (12)	0.0165 (9)	−0.0131 (9)	−0.0032 (8)	0.0019 (8)
C25	0.0395 (13)	0.0320 (12)	0.0350 (12)	−0.0170 (10)	−0.0258 (11)	0.0148 (10)
C17	0.0296 (11)	0.0199 (10)	0.0314 (11)	−0.0019 (8)	−0.0173 (9)	−0.0005 (8)
C24	0.0286 (11)	0.0268 (11)	0.0396 (13)	−0.0066 (9)	−0.0205 (10)	0.0070 (9)
C26	0.0370 (13)	0.0376 (12)	0.0238 (11)	−0.0174 (10)	−0.0167 (10)	0.0113 (9)
C13	0.0308 (12)	0.0300 (11)	0.0253 (11)	−0.0033 (9)	−0.0095 (9)	0.0054 (9)
C14	0.0473 (15)	0.0390 (14)	0.0298 (12)	−0.0109 (11)	−0.0141 (11)	0.0142 (10)
N6	0.0658 (18)	0.0405 (14)	0.0574 (16)	−0.0176 (13)	−0.0158 (14)	0.0110 (12)
C16	0.0437 (15)	0.0281 (12)	0.0463 (15)	0.0013 (10)	−0.0285 (12)	0.0066 (10)
C6	0.0349 (14)	0.0341 (13)	0.0485 (16)	−0.0094 (11)	−0.0072 (12)	−0.0007 (11)
C15	0.0581 (18)	0.0355 (13)	0.0418 (15)	−0.0081 (12)	−0.0278 (13)	0.0180 (11)
N4	0.0644 (19)	0.0479 (16)	0.129 (3)	−0.0260 (14)	−0.064 (2)	0.0281 (17)

Geometric parameters (Å, º)

Cu1—N2	1.9546 (18)	C19—H19	0.9500
Cu1—N3^i	1.9919 (18)	C23—C24	1.374 (3)
Cu1—N10	2.0109 (17)	C23—H23	0.9500
Cu1—N5	2.036 (2)	C29—C28	1.367 (3)
Cu1—N20	2.2111 (16)	C29—H29	0.9500
N10—C11	1.327 (3)	C5—N4	1.316 (4)
N10—C12	1.378 (3)	C18—C17	1.408 (3)
N20—C21	1.327 (3)	C18—H18	0.9500
N20—C22	1.374 (3)	C28—H28	0.9500
N2—C2	1.150 (3)	C25—C26	1.361 (4)
N3—C3	1.149 (3)	C25—C24	1.411 (3)
N3—Cu1^i	1.9919 (18)	C25—H25	0.9500
N1—C3	1.299 (3)	C17—C16	1.419 (3)
N1—C2	1.303 (3)	C24—H24	0.9500
N5—C5	1.091 (3)	C26—H26	0.9500
C21—C29	1.416 (3)	C13—C14	1.373 (3)
C21—C11	1.492 (3)	C13—H13	0.9500
C11—C19	1.412 (3)	C14—C15	1.406 (4)
C22—C23	1.413 (3)	C14—H14	0.9500
C22—C27	1.423 (3)	N6—C6	1.135 (4)
C12—C13	1.412 (3)	C16—C15	1.357 (4)
C12—C17	1.416 (3)	C16—H16	0.9500
C27—C28	1.408 (3)	C6—N4	1.326 (4)
C27—C26	1.422 (3)	C15—H15	0.9500
C19—C18	1.364 (3)
N2—Cu1—N3^i	88.16 (7)	C24—C23—C22	120.0 (2)
N2—Cu1—N10	169.15 (7)	C24—C23—H23	120.0
N3^i—Cu1—N10	88.86 (7)	C22—C23—H23	120.0
N2—Cu1—N5	89.86 (8)	C28—C29—C21	119.2 (2)
N3^i—Cu1—N5	157.78 (9)	C28—C29—H29	120.4
N10—Cu1—N5	88.96 (7)	C21—C29—H29	120.4
N2—Cu1—N20	112.45 (7)	N5—C5—N4	173.0 (3)
N3^i—Cu1—N20	98.72 (7)	C19—C18—C17	120.2 (2)
N10—Cu1—N20	78.32 (7)	C19—C18—H18	119.9
N5—Cu1—N20	102.48 (7)	C17—C18—H18	119.9
C11—N10—C12	120.35 (17)	C29—C28—C27	119.77 (19)
C11—N10—Cu1	117.64 (13)	C29—C28—H28	120.1
C12—N10—Cu1	121.95 (14)	C27—C28—H28	120.1
C21—N20—C22	118.59 (17)	C26—C25—C24	120.4 (2)
C21—N20—Cu1	111.27 (13)	C26—C25—H25	119.8
C22—N20—Cu1	130.12 (13)	C24—C25—H25	119.8
C2—N2—Cu1	158.34 (17)	C18—C17—C12	117.95 (19)
C3—N3—Cu1^i	156.25 (17)	C18—C17—C16	123.0 (2)
C3—N1—C2	119.41 (18)	C12—C17—C16	119.0 (2)
C5—N5—Cu1	145.8 (2)	C23—C24—C25	120.8 (2)
N20—C21—C29	122.89 (19)	C23—C24—H24	119.6
N20—C21—C11	116.06 (17)	C25—C24—H24	119.6
C29—C21—C11	121.05 (18)	C25—C26—C27	120.5 (2)
N10—C11—C19	121.39 (19)	C25—C26—H26	119.8
N10—C11—C21	116.58 (17)	C27—C26—H26	119.8
C19—C11—C21	122.03 (18)	C14—C13—C12	119.6 (2)
N2—C2—N1	173.1 (2)	C14—C13—H13	120.2
N3—C3—N1	172.7 (2)	C12—C13—H13	120.2
N20—C22—C23	119.08 (18)	C13—C14—C15	120.9 (2)
N20—C22—C27	121.67 (19)	C13—C14—H14	119.6
C23—C22—C27	119.24 (19)	C15—C14—H14	119.6
N10—C12—C13	119.83 (19)	C15—C16—C17	120.3 (2)
N10—C12—C17	120.56 (19)	C15—C16—H16	119.9
C13—C12—C17	119.60 (19)	C17—C16—H16	119.9
C28—C27—C26	123.0 (2)	N6—C6—N4	175.4 (3)
C28—C27—C22	117.91 (19)	C16—C15—C14	120.6 (2)
C26—C27—C22	119.1 (2)	C16—C15—H15	119.7
C18—C19—C11	119.5 (2)	C14—C15—H15	119.7
C18—C19—H19	120.2	C5—N4—C6	120.9 (3)
C11—C19—H19	120.2

Symmetry code: (i) −x+1, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C23—H23···N2	0.95	2.51	3.391 (3)	154