Methyl 2-(2-pyridyl)­quinoline-4-carboxyl­ate

The synthesis and structure of the title compound, C₁₆H₁₂N₂O₂, are described. The observed conformation in the solid state is similar to that determined previously by ¹H NMR and two-dimensional COSY NMR analysis.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.041
• wR factor = 0.107
• Data-to-parameter ratio = 8.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           27.41
         From the CIF: _reflns_number_total               1538
         Count of symmetry unique reflns         1605
         Completeness (_total/calc)             95.83%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         0
         Fraction of Friedel pairs measured     0.000
         Are heavy atom types Z>Si present           no
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.

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S1. Comment

The photophysical properties and the excited-state chemistry of tris(bipyridyl)ruthenium(II) complexes have been investigated to a great extent because of their unique and interesting features such as chemical stability, reversible redox property, long excited-state life time and chelation properties (Juris et al., 1988). 2,2'-Bipyridine is the prototype ligand of almost all reported Ru(II) tris-chelate complexes (Kaes et al., 2000). Synthetically, it lacks a suitable peripheral chemical functionality that allows it to be bound into a diverse array of substrates. To address this dilemma, a rigorous synthetic research effort towards the structural variation of the commonly used ligands, such as bipyridines, phenanthrolines and terpyridines, must be conducted in order to develop such analogues, where differences in electronic and steric properties may lead to modification of the resulting metal complexes. We have synthesized and characterized a novel diimine ligand, methyl 2-(2-pyridyl)quinoline-4-carboxylate, (I), and covalently bound it into a polymeric matrix (Farah et al., 2000) and on to CdS nanoparticle (Veinot et al., 2000). We report here the synthesis and crystal structure of (I).

The ORTEPII (Johnson, 1976) diagram of (I) (Fig. 1) reveals the expected conformation of the ligand in the solid state as the two N atoms are in the trans configuration to minimize electronic repulsion. The packing (Fig. 2) also precludes interaction between adjacent molecules and reveals an alternating flat/tilt array typical of molecular crystals (Gray & Goodby, 1984). All observed C—C, C—N and C—O bond lengths are in good agreement with those reported in the literature and do not merit any further discussion (International Tables for Crystallography, 1995, Vol. C).

S2. Experimental

4.00 g (16 mmol) of 2-(2-pyridyl)-4-carboxyquinolic acid were dissolved in 70 ml of freshly distilled benzene. 4.10 g (128 mmol) of methanol and 5 ml of H₂SO₄ were added successively and the reaction mixture was refluxed overnight. The reaction product was then poured into 150 ml of water and extracted with (3 x 30 ml) of ether. The ethereal layer was washed with 5% NaHCO₃, then with water and was dried over MgSO₄. After removal of the solvent the resultant product was recrystallized from ethanol; yield: 3.47 g (81%).

Computing details

Data collection: COLLECT (Nonius BV, 1997-2001); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXTL/PC (Sheldrick 1999); program(s) used to refine structure: SHELXTL/PC; molecular graphics: SHELXTL/PC; software used to prepare material for publication: SHELXTL/PC.

Figures

	Fig. 1. ORTEPII drawing with atomic numbering of the title compound. Displacement ellipsoids are plotted with 50% probability. H atoms have been omitted for clarity.
	Fig. 2. Packing diagram of the title compound viewed along the b axis.

2-(2-pyridyl)-4-methylcarboxyquinoline

Crystal data

C16H12N2O2	F(000) = 552
Mr = 264.28	Dx = 1.420 Mg m^−3
Monoclinic, C2	Mo Kα radiation, λ = 0.71073 Å
a = 29.332 (3) Å	Cell parameters from 9674 reflections
b = 3.8551 (2) Å	θ = 2.6–27.5°
c = 11.0753 (11) Å	µ = 0.10 mm^−1
β = 99.341 (3)°	T = 100 K
V = 1235.76 (19) Å^3	Needle, light-gold
Z = 4	0.20 × 0.10 × 0.05 mm

Data collection

Nonius KappaCCD diffractometer	1538 independent reflections
Radiation source: fine-focus sealed tube	1352 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
Detector resolution: 9 pixels mm^-1	θmax = 27.4°, θmin = 2.8°
ϕ scans, and ω scans with κ offsets	h = 0→37
Absorption correction: multi-scan (DENZO-SMN; Otwinowski & Minor, 1997)	k = 0→4
Tmin = 0.981, Tmax = 0.995	l = −14→14
9674 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.107	H-atom parameters constrained
S = 0.89	w = 1/[σ^2(Fo^2) + (0.0647P)^2 + 0.8852P] where P = (Fo^2 + 2Fc^2)/3
1538 reflections	(Δ/σ)max < 0.001
181 parameters	Δρmax = 0.18 e Å^−3
1 restraint	Δρmin = −0.20 e Å^−3

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. 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 (Ų)

	x	y	z	Uiso*/Ueq
N1	0.82452 (6)	0.7699 (6)	0.01206 (17)	0.0208 (5)
N2	0.92066 (7)	0.6025 (6)	0.25009 (16)	0.0228 (5)
O1	0.92109 (6)	0.3202 (6)	−0.30410 (14)	0.0327 (5)
O2	0.95660 (5)	0.1620 (5)	−0.11900 (14)	0.0240 (4)
C1	0.99360 (8)	0.0141 (7)	−0.1759 (2)	0.0248 (6)
H1B	1.0166	−0.0859	−0.1141	0.030*
H1C	0.9811	−0.1623	−0.2330	0.030*
H1D	1.0074	0.1931	−0.2182	0.030*
C2	0.86551 (8)	0.6572 (6)	0.0646 (2)	0.0188 (5)
C3	0.89718 (8)	0.4967 (7)	−0.0019 (2)	0.0197 (5)
H3A	0.9260	0.4092	0.0405	0.024*
C4	0.88676 (8)	0.4671 (7)	−0.1266 (2)	0.0189 (5)
C5	0.84330 (8)	0.5973 (7)	−0.1878 (2)	0.0190 (5)
C6	0.82812 (8)	0.5928 (7)	−0.3165 (2)	0.0217 (5)
H6A	0.8477	0.4973	−0.3697	0.026*
C7	0.78599 (8)	0.7245 (7)	−0.3652 (2)	0.0230 (5)
H7A	0.7763	0.7214	−0.4522	0.028*
C8	0.75610 (8)	0.8644 (7)	−0.2894 (2)	0.0237 (5)
H8A	0.7265	0.9557	−0.3251	0.028*
C9	0.76929 (8)	0.8713 (7)	−0.1659 (2)	0.0224 (5)
H9A	0.7488	0.9642	−0.1147	0.027*
C10	0.81308 (8)	0.7402 (7)	−0.1119 (2)	0.0204 (5)
C11	0.87838 (8)	0.7118 (6)	0.1986 (2)	0.0195 (5)
C12	0.84820 (8)	0.8782 (7)	0.2654 (2)	0.0234 (6)
H12A	0.8184	0.9551	0.2258	0.028*
C13	0.86200 (9)	0.9307 (7)	0.3892 (2)	0.0269 (6)
H13A	0.8420	1.0447	0.4371	0.032*
C14	0.90544 (9)	0.8163 (8)	0.4435 (2)	0.0276 (6)
H14A	0.9159	0.8479	0.5295	0.033*
C15	0.93310 (9)	0.6549 (8)	0.3704 (2)	0.0263 (6)
H15A	0.9631	0.5754	0.4083	0.032*
C16	0.92212 (8)	0.3106 (7)	−0.1950 (2)	0.0200 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0189 (10)	0.0233 (12)	0.0212 (9)	−0.0015 (9)	0.0062 (7)	0.0005 (9)
N2	0.0216 (10)	0.0270 (12)	0.0202 (9)	−0.0015 (9)	0.0049 (8)	0.0001 (9)
O1	0.0294 (10)	0.0493 (13)	0.0200 (8)	0.0111 (10)	0.0062 (7)	−0.0023 (9)
O2	0.0174 (8)	0.0318 (11)	0.0237 (8)	0.0066 (8)	0.0059 (6)	0.0003 (8)
C1	0.0194 (11)	0.0284 (15)	0.0283 (12)	0.0033 (11)	0.0084 (9)	−0.0035 (11)
C2	0.0167 (10)	0.0194 (13)	0.0212 (11)	−0.0039 (10)	0.0057 (8)	0.0010 (10)
C3	0.0172 (11)	0.0209 (13)	0.0215 (11)	−0.0013 (10)	0.0047 (9)	0.0002 (10)
C4	0.0170 (11)	0.0186 (12)	0.0218 (11)	−0.0018 (10)	0.0053 (9)	−0.0019 (9)
C5	0.0173 (11)	0.0182 (12)	0.0218 (11)	−0.0012 (10)	0.0038 (8)	0.0004 (10)
C6	0.0216 (12)	0.0224 (13)	0.0218 (11)	−0.0013 (10)	0.0056 (9)	−0.0024 (10)
C7	0.0219 (11)	0.0253 (14)	0.0209 (11)	−0.0027 (11)	0.0010 (9)	0.0017 (10)
C8	0.0169 (11)	0.0250 (13)	0.0291 (12)	−0.0004 (11)	0.0035 (9)	0.0049 (11)
C9	0.0187 (11)	0.0207 (13)	0.0293 (12)	0.0005 (10)	0.0083 (9)	0.0006 (11)
C10	0.0179 (11)	0.0212 (13)	0.0227 (11)	−0.0032 (10)	0.0052 (9)	0.0013 (10)
C11	0.0199 (11)	0.0199 (13)	0.0198 (11)	−0.0045 (10)	0.0063 (8)	0.0003 (10)
C12	0.0235 (12)	0.0244 (14)	0.0235 (12)	−0.0007 (11)	0.0073 (9)	−0.0014 (11)
C13	0.0313 (14)	0.0288 (15)	0.0232 (12)	−0.0046 (12)	0.0121 (10)	−0.0045 (11)
C14	0.0352 (14)	0.0289 (15)	0.0186 (11)	−0.0061 (13)	0.0043 (10)	−0.0025 (11)
C15	0.0256 (12)	0.0307 (16)	0.0226 (11)	−0.0019 (12)	0.0038 (9)	0.0029 (11)
C16	0.0176 (11)	0.0214 (13)	0.0215 (11)	−0.0008 (10)	0.0042 (9)	−0.0001 (10)

Geometric parameters (Å, º)

N1—C2	1.322 (3)	C5—C10	1.427 (3)
N1—C10	1.364 (3)	C6—C7	1.364 (3)
N2—C15	1.338 (3)	C6—H6A	0.9600
N2—C11	1.346 (3)	C7—C8	1.415 (3)
O1—C16	1.204 (3)	C7—H7A	0.9600
O2—C16	1.335 (3)	C8—C9	1.360 (3)
O2—C1	1.456 (3)	C8—H8A	0.9601
C1—H1B	0.9601	C9—C10	1.419 (3)
C1—H1C	0.9600	C9—H9A	0.9600
C1—H1D	0.9602	C11—C12	1.398 (3)
C2—C3	1.418 (3)	C12—C13	1.380 (3)
C2—C11	1.485 (3)	C12—H12A	0.9599
C3—C4	1.369 (3)	C13—C14	1.389 (4)
C3—H3A	0.9601	C13—H13A	0.9599
C4—C5	1.434 (3)	C14—C15	1.384 (3)
C4—C16	1.507 (3)	C14—H14A	0.9601
C5—C6	1.423 (3)	C15—H15A	0.9601
C2—N1—C10	118.25 (19)	C9—C8—C7	120.1 (2)
C15—N2—C11	117.3 (2)	C9—C8—H8A	119.8
C16—O2—C1	115.88 (17)	C7—C8—H8A	120.0
O2—C1—H1B	109.6	C8—C9—C10	120.5 (2)
O2—C1—H1C	109.3	C8—C9—H9A	119.8
H1B—C1—H1C	109.5	C10—C9—H9A	119.7
O2—C1—H1D	109.5	N1—C10—C9	116.9 (2)
H1B—C1—H1D	109.5	N1—C10—C5	123.4 (2)
H1C—C1—H1D	109.5	C9—C10—C5	119.7 (2)
N1—C2—C3	122.7 (2)	N2—C11—C12	122.6 (2)
N1—C2—C11	117.32 (19)	N2—C11—C2	116.49 (19)
C3—C2—C11	119.97 (19)	C12—C11—C2	120.9 (2)
C4—C3—C2	120.2 (2)	C13—C12—C11	119.0 (2)
C4—C3—H3A	119.9	C13—C12—H12A	120.5
C2—C3—H3A	119.9	C11—C12—H12A	120.5
C3—C4—C5	118.9 (2)	C12—C13—C14	118.9 (2)
C3—C4—C16	118.8 (2)	C12—C13—H13A	120.6
C5—C4—C16	122.26 (19)	C14—C13—H13A	120.5
C6—C5—C10	118.1 (2)	C15—C14—C13	118.2 (2)
C6—C5—C4	125.4 (2)	C15—C14—H14A	120.9
C10—C5—C4	116.49 (19)	C13—C14—H14A	120.9
C7—C6—C5	120.5 (2)	N2—C15—C14	124.0 (2)
C7—C6—H6A	119.7	N2—C15—H15A	118.0
C5—C6—H6A	119.8	C14—C15—H15A	118.0
C6—C7—C8	121.1 (2)	O1—C16—O2	122.6 (2)
C6—C7—H7A	119.5	O1—C16—C4	125.8 (2)
C8—C7—H7A	119.4	O2—C16—C4	111.53 (18)