Bis(1,4-di­aza­cyclo­heptane-N,N')­nickel(II) diperchlorate

The title compound, [Ni(C₅H₁₂N₂)₂](ClO₄)₂, consists of discrete [Ni(C₅H₁₂N₂)₂]²⁺ cations and perchlorate anions. The Ni^II atom is at the center of symmetry and is coordinated in a square-planar manner by the nitro­gen donors of a pair of mesocyclic 1,4-di­aza­cyclo­heptane (DACH) ligands. Both DACH rings adopt boat conformations in the trans form. The perchlorate O atoms are hydrogen bonded with the nitro­gen donors of the DACH rings to form a macrocycle-like system.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.051
• wR factor = 0.141
• Data-to-parameter ratio = 13.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_737  Alert C D...A   Calc    2.997(7), Rep    2.997(3) ....       2.33 s.u-Ratio
                     N1   -O3      1.555   2.645


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

Mesocyclic ligands (molecules contain seven- to ten-membered rings) occupy an important place between acyclic and macrocyclic ligands due to offer several attractive features as a framework for ligand development with exceptionally strong ligand fields, unique conformational requirements and the potential for further functionalization (Musker, 1992; Grapperhaus & Darensbourg, 1998; Bu et al., 2000). 1,5-Diazacyclooctane (DACO) and 1,4-diazacycloheptane (DACH) are the most typical examples of the diazamesocyclic ligands. However, comparison of the widely investigation of DACO, structural studies on DACH are still quite rare (Musker, 1992; Allen et al., 1996). As part of our effort to further develop this interesting system, we report herein the synthesis and X-ray crystal structure of a Ni^II complex of DACH, namely the title compound, (I).

In the complex cation, the Ni^II center is four-coordinated, forming an exact plane, with the Ni1 atom at the center of symmetry (Fig. 1). The Ni—N1 and Ni—N2 bond distances are 1.911 (4) and 1.915 (4) Å, respectively, and are nearly equivalent. The chelate N1—Ni1—N2 angle is 81.06 (17)°, and slightly smaller than the non-chelate N1—Ni1—N2ⁱ angle [symmetry code: (i) -x, -y, -z]. The C—C bond distances in the methylene groups of DACH are in the range 1.499 (8)–1.537 (7) Å, which are normal aliphatic C—C bonds with sp³ hybridization. Both DACH moieties in the complex adopt the boat conformation in a trans form due to the central symmetry, which is similar to the structure of [Ni(DACH)₂]Cl₂·2H₂O (Hussain, 1983). The perchlorate ions have no close contacts to the Ni^II centers, since the shortest axial distance for Ni···O is 3.925 (3) Å.

The [Ni(DACH)₂]²⁺ unit carries two perchlorate ions which are hydrogen bonded to the nitrogen donors of DACH (Fig. 2). These hydrogen bonds form a macrocycle-like ring system including a pair of N—-H···O···N–H bridges, which is similar to the structure of [Ni(DACO)₂]Br₂ (Du et al., 2000).

S2. Experimental

A mixture of Ni(ClO₄)₂·6H₂O (220 mg, 0.6 mmol) and 1,4-diazacycloheptane (120 mg, 1.2 mmol) was dissolved in methanol (15 ml) at room temperature. A yellow powder precipitated immediately. The complex was filtered off and washed several times with anhydrous ether. Yield: 253 mg (92%). Yellow block-shaped single crystals of (I) were grown from CH₃COCH₃/CH₃OH (5:1). FT–IR data (KBr pellet, cm^-1): 3268 (m), 3123 (m), 3083 (m), 2948 (w), 1635 (w), 1473 (m), 1122 (versus), 1109 (versus), 988 (m), 636 (s), 626 (s). Analysis calculated for (I): C 26.23, H 5.28, N 12.24%; found: C 26.41, H 5.40, N 12.13%.

S3. Refinement

The H atoms attached to C and N atoms were placed in geometrically calculated positions and included in the final refinement as riding with displacement parameters derived from the atoms to which they were bonded.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL (Bruker, 1998).

Figures

	Fig. 1. ORTEP view (Johnson, 1976) of the cation of the title complex with 30% probability ellipsoids.
	Fig. 2. Molecular packing diagram in the unit cell of (I) (H atoms not mentioned in the text have been omitted for clarity).

Bis(1,4-diazacycloheptane-N,N')nickel(II) diperchlorate

Crystal data

[Ni(C5H12N2)2](ClO4)2	F(000) = 476
Mr = 457.94	Dx = 1.724 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.7899 (17) Å	Cell parameters from 3489 reflections
b = 8.071 (2) Å	θ = 2.5–25.0°
c = 16.152 (4) Å	µ = 1.45 mm^−1
β = 94.760 (5)°	T = 293 K
V = 882.0 (4) Å^3	Prism, yellow
Z = 2	0.20 × 0.20 × 0.15 mm

Data collection

Bruker SMART 1000 diffractometer	968 reflections with I > 2σ(I)
ω scans	Rint = 0.052
Absorption correction: multi-scan [SAINT (Bruker 1998) and SADABS (Sheldrick, 1997)]	θmax = 25.0°
Tmin = 0.760, Tmax = 0.812	h = −8→8
3544 measured reflections	k = −9→9
1557 independent reflections	l = −8→19

Refinement

Refinement on F^2	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.051	w = 1/[σ^2(Fo^2) + (0.075P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.141	(Δ/σ)max = 0.007
S = 0.98	Δρmax = 0.65 e Å^−3
1557 reflections	Δρmin = −0.41 e Å^−3
115 parameters

Special details

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. Single crystal X-ray diffraction measurements were carried out on a BRUKER SMART 1000 CCD diffractometer. The structure was solved by direct and difference Fourier methods and refined by full-matrix least-squares methods.

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

	x	y	z	Uiso*/Ueq
Ni1	0.0000	0.0000	0.0000	0.0265 (3)
N1	0.1841 (6)	0.0219 (5)	0.0955 (3)	0.0314 (11)
H1C	0.2933	−0.0403	0.0885	0.038*
N2	−0.1095 (6)	0.1921 (5)	0.0486 (3)	0.0325 (11)
H2C	−0.1973	0.2422	0.0110	0.039*
C1	0.0855 (9)	−0.0405 (7)	0.1691 (4)	0.0423 (16)
H1A	0.1838	−0.0559	0.2155	0.051*
H1B	0.0247	−0.1470	0.1558	0.051*
C2	−0.0711 (9)	0.0804 (8)	0.1935 (4)	0.0478 (16)
H2A	−0.1464	0.0280	0.2348	0.057*
H2B	−0.0056	0.1764	0.2193	0.057*
C3	−0.2118 (8)	0.1384 (8)	0.1231 (4)	0.0431 (15)
H3A	−0.2884	0.2304	0.1419	0.052*
H3B	−0.3030	0.0493	0.1069	0.052*
C4	0.0611 (8)	0.3057 (7)	0.0713 (4)	0.0383 (15)
H4A	0.0280	0.3816	0.1146	0.046*
H4B	0.0914	0.3700	0.0233	0.046*
C5	0.2402 (8)	0.1995 (7)	0.1022 (4)	0.0388 (15)
H5A	0.3498	0.2215	0.0688	0.047*
H5B	0.2814	0.2268	0.1595	0.047*
Cl1	0.4644 (2)	0.15911 (19)	0.37453 (10)	0.0456 (5)
O1	0.4525 (13)	0.2417 (11)	0.2992 (4)	0.160 (4)
O2	0.3003 (13)	0.0729 (12)	0.3883 (6)	0.193 (5)
O3	0.4917 (9)	0.2842 (7)	0.4364 (4)	0.098 (2)
O4	0.6346 (14)	0.0742 (12)	0.3836 (8)	0.216 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0243 (5)	0.0296 (5)	0.0245 (5)	0.0070 (4)	−0.0039 (4)	−0.0033 (5)
N1	0.028 (2)	0.038 (3)	0.027 (2)	0.011 (2)	−0.0032 (19)	−0.002 (2)
N2	0.028 (3)	0.037 (3)	0.030 (3)	0.010 (2)	−0.006 (2)	−0.001 (2)
C1	0.051 (4)	0.041 (4)	0.033 (3)	−0.001 (3)	−0.004 (3)	0.009 (3)
C2	0.052 (4)	0.056 (4)	0.038 (4)	−0.001 (3)	0.013 (3)	−0.007 (3)
C3	0.027 (3)	0.052 (4)	0.051 (4)	0.003 (3)	0.009 (3)	−0.013 (3)
C4	0.043 (4)	0.026 (3)	0.045 (4)	−0.004 (3)	−0.001 (3)	−0.005 (3)
C5	0.027 (3)	0.045 (3)	0.043 (4)	−0.005 (3)	−0.001 (3)	0.000 (3)
Cl1	0.0425 (9)	0.0430 (9)	0.0504 (10)	−0.0030 (7)	−0.0009 (7)	−0.0046 (8)
O1	0.193 (8)	0.211 (9)	0.068 (5)	−0.038 (7)	−0.035 (5)	0.043 (5)
O2	0.170 (8)	0.237 (9)	0.182 (8)	−0.174 (8)	0.075 (7)	−0.097 (8)
O3	0.112 (5)	0.096 (4)	0.088 (4)	−0.054 (4)	0.021 (4)	−0.023 (4)
O4	0.183 (9)	0.150 (7)	0.328 (15)	0.108 (7)	0.095 (10)	0.065 (9)

Geometric parameters (Å, º)

Ni1—N1	1.911 (4)	C2—H2A	0.9700
Ni1—N1^i	1.911 (4)	C2—H2B	0.9700
Ni1—N2	1.915 (4)	C3—H3A	0.9700
Ni1—N2^i	1.915 (4)	C3—H3B	0.9700
N1—C5	1.484 (7)	C4—C5	1.537 (7)
N1—C1	1.499 (7)	C4—H4A	0.9700
N1—H1C	0.9100	C4—H4B	0.9700
N2—C4	1.499 (6)	C5—H5A	0.9700
N2—C3	1.502 (7)	C5—H5B	0.9700
N2—H2C	0.9100	Cl1—O4	1.341 (8)
C1—C2	1.519 (8)	Cl1—O2	1.348 (6)
C1—H1A	0.9700	Cl1—O1	1.384 (7)
C1—H1B	0.9700	Cl1—O3	1.421 (6)
C2—C3	1.499 (8)
N1—Ni1—N1^i	180.0 (3)	C3—C2—H2B	108.6
N1—Ni1—N2	81.06 (17)	C1—C2—H2B	108.6
N1^i—Ni1—N2	98.94 (17)	H2A—C2—H2B	107.6
N1—Ni1—N2^i	98.94 (17)	C2—C3—N2	113.0 (4)
N1^i—Ni1—N2^i	81.06 (17)	C2—C3—H3A	109.0
N2—Ni1—N2^i	180.0 (3)	N2—C3—H3A	109.0
C5—N1—C1	113.3 (5)	C2—C3—H3B	109.0
C5—N1—Ni1	107.2 (3)	N2—C3—H3B	109.0
C1—N1—Ni1	107.7 (3)	H3A—C3—H3B	107.8
C5—N1—H1C	109.5	N2—C4—C5	108.2 (4)
C1—N1—H1C	109.5	N2—C4—H4A	110.1
Ni1—N1—H1C	109.5	C5—C4—H4A	110.1
C4—N2—C3	112.3 (4)	N2—C4—H4B	110.1
C4—N2—Ni1	106.1 (3)	C5—C4—H4B	110.1
C3—N2—Ni1	108.4 (3)	H4A—C4—H4B	108.4
C4—N2—H2C	110.0	N1—C5—C4	108.9 (4)
C3—N2—H2C	110.0	N1—C5—H5A	109.9
Ni1—N2—H2C	110.0	C4—C5—H5A	109.9
N1—C1—C2	111.0 (4)	N1—C5—H5B	109.9
N1—C1—H1A	109.4	C4—C5—H5B	109.9
C2—C1—H1A	109.4	H5A—C5—H5B	108.3
N1—C1—H1B	109.4	O4—Cl1—O2	115.8 (7)
C2—C1—H1B	109.4	O4—Cl1—O1	109.2 (7)
H1A—C1—H1B	108.0	O2—Cl1—O1	113.9 (6)
C3—C2—C1	114.8 (5)	O4—Cl1—O3	103.0 (7)
C3—C2—H2A	108.6	O2—Cl1—O3	108.2 (4)
C1—C2—H2A	108.6	O1—Cl1—O3	105.7 (5)

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1c···O3^ii	0.91	2.10	2.997 (3)	170
N2—H2c···O3^iii	0.91	2.35	3.137 (4)	144

Symmetry codes: (ii) −x+1, y−1/2, −z+1/2; (iii) x−1, −y+1/2, z−1/2.