Cyclo­trideca­none 2,4-dinitro­phenyl­hydrazone

In cyclo­trideca­none 2,4-dinitro­phenyl­hydrazone, C₁₉H₂₈N₄O₄, the 13-membered carbocycle exists in the triangular [337] conformation. The 2,4-dinitro­phenyl­hydrazone group is almost perpendicular to the 13-membered ring, with a dihedral angle of 82.66 (2)° between the mean planes. The dinitro­phenyl­hydrazone rings are packed parallel to each other and separated by 3.28 (1) Å. The NH group forms an intra­molecular hydrogen bond to a nitro O atom, and there is a weaker C—H...O inter­action between a cyclo­tridecane CH group and a symmetry-related 4-nitro O atom, with a C...O distance of 3.436 (2) Å and a 150° angle about the H atom. The structure, in combination with additional evidence, indicates that [337] is the preferred conformation of cyclo­tridecane and other simple 13-membered rings.

S1. Comment

The conformations of larger odd-numbered carbocycles such as cyclotridecane are less well characterized than those with an even number of ring atoms. Semiquantitative calculations for eight conformations of cyclotridecane predicted a lowest energy quinquangular [12433] conformation (Dale, 1973). Subsequently, MOLBUILD force-field calculations on five likely conformations and on 1,1-dimethylcyclotridecane suggested a [13333] conformational minimum (Anet & Rawdah, 1978). From experimental studies, low-temperature ¹H (127 K) and ¹³C (123 K) NMR spectra for cyclotridecane show some broadening of resonances, and no information on likely conformers could be extracted (Cheng, 1973). The linewidth for the ¹H signal at 127 K was 10 Hz. Several broadened resonances were found in the ¹³C NMR spectrum at 88 K (Gill et al., 2008).

The X-ray structure of the α,ω-bis (methyldodeca-1,12-diylammonio)hexane dibromide showed a quinquangular [13333] conformation for an ordered model and a similar [13333] and a [346] conformation for a disordered model (Rubin et al., 1984). An X-ray study of the dimethyl-1-hydroxycyclotridecylphosphonate showed two conformations, one of which was the [13333] conformation (Samuel & Weiss, 1969). Two other solid derivatives studied by X-ray crystallography include the cyclotridecanone oxime (II) at 113 K (Groth, 1979) and cyclotridecanone phenylsemicarbazone, (III), at 123 K (Groth, 1980). Both of these crystal structures showed the triangular [337] conformation.

This study reports an X-ray analysis of the crystal structure of (I) at 90 K. As found in (II) and (III), the 13-membered ring is present in a [337] conformation (Fig. 1). In the Dale (1973) system for nomenclature, corner positions are defined as those ring atoms having gauche torsion angles of the same sign on either side. The numbers of bonds between the corners are given in sequence within brackets. The torsion angles for the C₁₃ ring are summarized in Table 1, where C3, C6 and C9 are corners. In (I) and (II), the ring substituent is located on atom C1 (Fig. 1); in (III), the substituent is at an adjacent position (C13). The angle between the mean plane of the 13-ring and the phenyl ring in (I) is 82.66 (2)°. The dinitrophenylhydrazone rings pack parallel to each other around centers at (1, 1, 1/2) and are separated by 3.25 (s.u.?) Å (Fig. 2). The NH group forms an intramolecular hydrogen bond with nitro atom O1, forming a six-membered ring of graph set S(6) (Etter, 1990). Additionally, there is a weaker C—H···O interaction between C7 and O3ⁱ, with a C···O distance of 3.436 (2) Å [symmetry code: (i) -x + 2, -y + 2, -z + 1].

The similar macrocyclic ring conformation found for (I), (II) and (III) suggests that the [337] conformation may be preferred. This agrees with the results (Gill et al., 2008) of a stochastic search of cyclotridecane conformational space by MM4. Geminal disubstitution in the dibromide salt and hydroxy phosphonate derivatives described previously may influence their adopted conformations.

Related literature

For related literature, see: Anet & Rawdah (1978); Cheng (1973); Dale (1973); Etter (1990); Gill et al. (2008); Groth (1979, 1980); Rubin et al. (1984); Samuel & Weiss (1969); Zakharkin et al. (1962).

S2. Experimental

Compound (I) was synthesized by treatment of cyclotridecanone (0.2 g) with 2,4-dinitrophenylhydrazine solution (3 ml) prepared from 2,4-dinitrophenylhydrazine (1 g), concentrated sulfuric acid (5 ml), water (8 ml) and ethanol (25 ml). The dinitrophenylhydrazone derivative immediately precipitated from the solution and was isolated by filtration, washed with water, and recrystallized from ethanol [m.p. 377–378 K; literature m.p. 386.7–387.7 K (Zakharkin et al., 1962)]. The yellow blade-shaped crystals were grown by slow evaporation from ethanol.

S3. Refinement

The H atoms on C were placed in calculated positions, guided by difference maps, with C—H bond distances in the range 0.95–0.99Å and thereafter treated as riding aroms using the SHELXL97 (Sheldrick, 2008) defaults. The N—H hydrogen coordinates were refined. All H displacement parameters were assigned as 1.2U_eq(C or N).

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. A displacement ellipsoid plot (at the 50% probability level) of (I).
	Fig. 2. The unit cell of (I).

cyclotridecanone 2,4-dinitrophenylhydrazone

Crystal data

C19H28N4O4	Z = 2
Mr = 376.45	F(000) = 404
Triclinic, P1	Dx = 1.318 Mg m^−3
Hall symbol: -P 1	Melting point: 378 K
a = 7.7859 (10) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.8937 (10) Å	Cell parameters from 4832 reflections
c = 16.130 (2) Å	θ = 2.5–31.5°
α = 81.979 (7)°	µ = 0.09 mm^−1
β = 77.608 (8)°	T = 90 K
γ = 80.234 (8)°	Lath, yellow
V = 948.7 (2) Å^3	0.40 × 0.08 × 0.03 mm

Data collection

Nonius KappaCCD (with an Oxford Cryosystems Cryostream cooler) diffractometer	3974 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.029
Graphite monochromator	θmax = 31.5°, θmin = 2.6°
ω scans with κ offsets	h = −11→10
26226 measured reflections	k = −11→11
5518 independent reflections	l = −22→22

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.046	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.099	w = 1/[σ^2(Fo^2) + (0.0276P)^2 + 0.4695P] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
5518 reflections	Δρmax = 0.34 e Å^−3
248 parameters	Δρmin = −0.26 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0121 (14)

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
O1	0.64885 (12)	0.62443 (12)	0.46946 (6)	0.0187 (2)
O2	0.78601 (13)	0.72956 (13)	0.34616 (6)	0.0234 (2)
O3	1.04660 (13)	1.23977 (14)	0.30876 (6)	0.0276 (2)
O4	1.02088 (12)	1.38929 (12)	0.41552 (7)	0.0235 (2)
N1	0.49239 (13)	0.85568 (13)	0.68070 (6)	0.0131 (2)
N2	0.56946 (13)	0.80898 (14)	0.59983 (7)	0.0129 (2)
H2N	0.5568 (19)	0.710 (2)	0.5812 (9)	0.015*
N3	0.72727 (13)	0.73853 (14)	0.42281 (7)	0.0156 (2)
N4	0.98689 (14)	1.26911 (15)	0.38335 (7)	0.0185 (2)
C1	0.40503 (15)	0.74620 (16)	0.73223 (8)	0.0131 (2)
C2	0.31678 (16)	0.80125 (17)	0.81914 (8)	0.0158 (3)
H2A	0.3297	0.6999	0.8622	0.019*
H2B	0.1882	0.8359	0.8199	0.019*
C3	0.38806 (17)	0.94988 (17)	0.84634 (8)	0.0176 (3)
H3A	0.3096	0.9869	0.8996	0.021*
H3B	0.3832	1.0492	0.8016	0.021*
C4	0.57951 (17)	0.90273 (17)	0.86136 (8)	0.0170 (3)
H4A	0.6534	0.8443	0.8126	0.020*
H4B	0.6273	1.0106	0.8627	0.020*
C5	0.59681 (17)	0.78539 (18)	0.94393 (8)	0.0187 (3)
H5A	0.5380	0.6830	0.9453	0.022*
H5B	0.5330	0.8486	0.9930	0.022*
C6	0.78921 (18)	0.72372 (18)	0.95468 (9)	0.0208 (3)
H6A	0.8562	0.8232	0.9395	0.025*
H6B	0.7895	0.6821	1.0155	0.025*
C7	0.88498 (17)	0.57902 (17)	0.89995 (9)	0.0179 (3)
H7A	0.8649	0.6112	0.8409	0.021*
H7B	1.0143	0.5675	0.8981	0.021*
C8	0.82196 (17)	0.40480 (18)	0.93381 (9)	0.0192 (3)
H8A	0.6906	0.4236	0.9497	0.023*
H8B	0.8682	0.3603	0.9865	0.023*
C9	0.87789 (18)	0.26630 (17)	0.87187 (9)	0.0210 (3)
H9A	0.8326	0.1587	0.9004	0.025*
H9B	1.0093	0.2414	0.8590	0.025*
C10	0.81163 (17)	0.31571 (17)	0.78743 (9)	0.0187 (3)
H10A	0.8892	0.3940	0.7497	0.022*
H10B	0.8241	0.2097	0.7590	0.022*
C11	0.61887 (16)	0.40397 (17)	0.79641 (8)	0.0163 (3)
H11A	0.5409	0.3291	0.8363	0.020*
H11B	0.6070	0.5143	0.8212	0.020*
C12	0.55749 (17)	0.44035 (17)	0.71128 (8)	0.0166 (3)
H12A	0.5384	0.3301	0.6945	0.020*
H12B	0.6532	0.4857	0.6673	0.020*
C13	0.38514 (16)	0.57043 (16)	0.71237 (8)	0.0149 (2)
H13A	0.3508	0.5819	0.6560	0.018*
H13B	0.2884	0.5249	0.7557	0.018*
C14	0.66839 (15)	0.91866 (16)	0.54556 (8)	0.0125 (2)
C15	0.74814 (15)	0.88944 (16)	0.45985 (8)	0.0129 (2)
C16	0.84952 (15)	1.00571 (17)	0.40640 (8)	0.0145 (2)
H16	0.9020	0.9842	0.3493	0.017*
C17	0.87246 (15)	1.15210 (16)	0.43761 (8)	0.0151 (3)
C18	0.79480 (16)	1.18785 (16)	0.52117 (8)	0.0153 (3)
H18	0.8106	1.2906	0.5412	0.018*
C19	0.69566 (15)	1.07289 (16)	0.57367 (8)	0.0143 (2)
H19	0.6437	1.0971	0.6305	0.017*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0193 (4)	0.0185 (5)	0.0183 (5)	−0.0048 (4)	−0.0008 (4)	−0.0036 (4)
O2	0.0257 (5)	0.0298 (6)	0.0145 (5)	−0.0054 (4)	0.0014 (4)	−0.0083 (4)
O3	0.0274 (5)	0.0335 (6)	0.0175 (5)	−0.0068 (4)	0.0027 (4)	0.0047 (4)
O4	0.0195 (5)	0.0178 (5)	0.0316 (6)	−0.0048 (4)	−0.0028 (4)	0.0017 (4)
N1	0.0120 (5)	0.0151 (5)	0.0115 (5)	0.0003 (4)	−0.0016 (4)	−0.0025 (4)
N2	0.0135 (5)	0.0126 (5)	0.0123 (5)	−0.0016 (4)	−0.0014 (4)	−0.0026 (4)
N3	0.0129 (5)	0.0187 (6)	0.0149 (5)	0.0003 (4)	−0.0027 (4)	−0.0039 (4)
N4	0.0130 (5)	0.0192 (6)	0.0201 (6)	0.0000 (4)	−0.0030 (4)	0.0054 (5)
C1	0.0105 (5)	0.0144 (6)	0.0143 (6)	−0.0006 (4)	−0.0036 (4)	−0.0014 (5)
C2	0.0133 (5)	0.0179 (6)	0.0153 (6)	−0.0026 (5)	0.0007 (5)	−0.0029 (5)
C3	0.0206 (6)	0.0150 (6)	0.0159 (6)	−0.0013 (5)	−0.0003 (5)	−0.0043 (5)
C4	0.0192 (6)	0.0165 (6)	0.0161 (6)	−0.0056 (5)	−0.0015 (5)	−0.0032 (5)
C5	0.0227 (6)	0.0197 (7)	0.0138 (6)	−0.0042 (5)	−0.0015 (5)	−0.0037 (5)
C6	0.0243 (7)	0.0227 (7)	0.0180 (7)	−0.0065 (5)	−0.0073 (5)	−0.0027 (5)
C7	0.0165 (6)	0.0204 (7)	0.0177 (7)	−0.0060 (5)	−0.0039 (5)	−0.0003 (5)
C8	0.0195 (6)	0.0203 (7)	0.0187 (7)	−0.0062 (5)	−0.0063 (5)	0.0032 (5)
C9	0.0198 (6)	0.0165 (7)	0.0271 (8)	−0.0015 (5)	−0.0089 (5)	0.0019 (5)
C10	0.0185 (6)	0.0152 (6)	0.0220 (7)	−0.0009 (5)	−0.0041 (5)	−0.0020 (5)
C11	0.0176 (6)	0.0137 (6)	0.0177 (6)	−0.0022 (5)	−0.0044 (5)	−0.0009 (5)
C12	0.0199 (6)	0.0132 (6)	0.0174 (6)	−0.0013 (5)	−0.0050 (5)	−0.0034 (5)
C13	0.0154 (6)	0.0153 (6)	0.0149 (6)	−0.0036 (5)	−0.0039 (5)	−0.0018 (5)
C14	0.0092 (5)	0.0153 (6)	0.0123 (6)	0.0008 (4)	−0.0036 (4)	0.0006 (5)
C15	0.0111 (5)	0.0139 (6)	0.0135 (6)	0.0010 (4)	−0.0041 (4)	−0.0020 (5)
C16	0.0102 (5)	0.0195 (6)	0.0122 (6)	0.0015 (5)	−0.0029 (4)	0.0001 (5)
C17	0.0114 (5)	0.0156 (6)	0.0162 (6)	−0.0014 (5)	−0.0024 (5)	0.0044 (5)
C18	0.0131 (5)	0.0133 (6)	0.0190 (6)	0.0001 (4)	−0.0045 (5)	−0.0008 (5)
C19	0.0126 (5)	0.0147 (6)	0.0145 (6)	0.0004 (4)	−0.0018 (4)	−0.0023 (5)

Geometric parameters (Å, º)

O1—N3	1.2453 (14)	C7—H7A	0.9900
O2—N3	1.2302 (14)	C7—H7B	0.9900
O3—N4	1.2323 (15)	C8—C9	1.530 (2)
O4—N4	1.2332 (15)	C8—H8A	0.9900
N1—C1	1.2871 (16)	C8—H8B	0.9900
N1—N2	1.3859 (14)	C9—C10	1.5357 (19)
N2—C14	1.3545 (16)	C9—H9A	0.9900
N2—H2N	0.899 (15)	C9—H9B	0.9900
N3—C15	1.4520 (16)	C10—C11	1.5294 (18)
N4—C17	1.4600 (16)	C10—H10A	0.9900
C1—C13	1.5067 (17)	C10—H10B	0.9900
C1—C2	1.5104 (17)	C11—C12	1.5236 (18)
C2—C3	1.5317 (18)	C11—H11A	0.9900
C2—H2A	0.9900	C11—H11B	0.9900
C2—H2B	0.9900	C12—C13	1.5436 (18)
C3—C4	1.5365 (18)	C12—H12A	0.9900
C3—H3A	0.9900	C12—H12B	0.9900
C3—H3B	0.9900	C13—H13A	0.9900
C4—C5	1.5298 (18)	C13—H13B	0.9900
C4—H4A	0.9900	C14—C19	1.4198 (17)
C4—H4B	0.9900	C14—C15	1.4221 (17)
C5—C6	1.5335 (19)	C15—C16	1.3934 (17)
C5—H5A	0.9900	C16—C17	1.3754 (18)
C5—H5B	0.9900	C16—H16	0.9500
C6—C7	1.5329 (19)	C17—C18	1.4001 (18)
C6—H6A	0.9900	C18—C19	1.3708 (17)
C6—H6B	0.9900	C18—H18	0.9500
C7—C8	1.5279 (18)	C19—H19	0.9500
C1—N1—N2	116.91 (10)	C7—C8—H8B	108.5
C14—N2—N1	118.09 (10)	C9—C8—H8B	108.5
C14—N2—H2N	118.2 (9)	H8A—C8—H8B	107.5
N1—N2—H2N	123.7 (9)	C8—C9—C10	114.42 (11)
O2—N3—O1	122.56 (11)	C8—C9—H9A	108.7
O2—N3—C15	118.57 (11)	C10—C9—H9A	108.7
O1—N3—C15	118.87 (10)	C8—C9—H9B	108.7
O3—N4—O4	123.97 (11)	C10—C9—H9B	108.7
O3—N4—C17	118.08 (11)	H9A—C9—H9B	107.6
O4—N4—C17	117.93 (11)	C11—C10—C9	114.84 (11)
N1—C1—C13	125.20 (11)	C11—C10—H10A	108.6
N1—C1—C2	116.31 (11)	C9—C10—H10A	108.6
C13—C1—C2	118.49 (10)	C11—C10—H10B	108.6
C1—C2—C3	115.78 (10)	C9—C10—H10B	108.6
C1—C2—H2A	108.3	H10A—C10—H10B	107.5
C3—C2—H2A	108.3	C12—C11—C10	112.42 (11)
C1—C2—H2B	108.3	C12—C11—H11A	109.1
C3—C2—H2B	108.3	C10—C11—H11A	109.1
H2A—C2—H2B	107.4	C12—C11—H11B	109.1
C2—C3—C4	113.67 (11)	C10—C11—H11B	109.1
C2—C3—H3A	108.8	H11A—C11—H11B	107.9
C4—C3—H3A	108.8	C11—C12—C13	114.12 (11)
C2—C3—H3B	108.8	C11—C12—H12A	108.7
C4—C3—H3B	108.8	C13—C12—H12A	108.7
H3A—C3—H3B	107.7	C11—C12—H12B	108.7
C5—C4—C3	114.05 (11)	C13—C12—H12B	108.7
C5—C4—H4A	108.7	H12A—C12—H12B	107.6
C3—C4—H4A	108.7	C1—C13—C12	112.53 (10)
C5—C4—H4B	108.7	C1—C13—H13A	109.1
C3—C4—H4B	108.7	C12—C13—H13A	109.1
H4A—C4—H4B	107.6	C1—C13—H13B	109.1
C4—C5—C6	114.09 (11)	C12—C13—H13B	109.1
C4—C5—H5A	108.7	H13A—C13—H13B	107.8
C6—C5—H5A	108.7	N2—C14—C19	119.68 (11)
C4—C5—H5B	108.7	N2—C14—C15	123.60 (11)
C6—C5—H5B	108.7	C19—C14—C15	116.73 (11)
H5A—C5—H5B	107.6	C16—C15—C14	121.58 (11)
C7—C6—C5	113.69 (11)	C16—C15—N3	116.27 (11)
C7—C6—H6A	108.8	C14—C15—N3	122.14 (11)
C5—C6—H6A	108.8	C17—C16—C15	118.95 (12)
C7—C6—H6B	108.8	C17—C16—H16	120.5
C5—C6—H6B	108.8	C15—C16—H16	120.5
H6A—C6—H6B	107.7	C16—C17—C18	121.64 (11)
C8—C7—C6	112.77 (11)	C16—C17—N4	119.05 (11)
C8—C7—H7A	109.0	C18—C17—N4	119.26 (11)
C6—C7—H7A	109.0	C19—C18—C17	119.25 (12)
C8—C7—H7B	109.0	C19—C18—H18	120.4
C6—C7—H7B	109.0	C17—C18—H18	120.4
H7A—C7—H7B	107.8	C18—C19—C14	121.84 (12)
C7—C8—C9	115.28 (11)	C18—C19—H19	119.1
C7—C8—H8A	108.5	C14—C19—H19	119.1
C9—C8—H8A	108.5
C1—N1—N2—C14	−177.27 (11)	C19—C14—C15—C16	0.62 (17)
N2—N1—C1—C13	1.98 (17)	N2—C14—C15—N3	0.94 (18)
C13—C1—C2—C3	161.03 (11)	C19—C14—C15—N3	−178.70 (10)
C2—C1—C13—C12	−106.70 (12)	O2—N3—C15—C16	−6.00 (16)
C1—C2—C3—C4	−67.14 (15)	O1—N3—C15—C16	174.88 (10)
C2—C3—C4—C5	−74.04 (14)	O2—N3—C15—C14	173.35 (11)
C3—C4—C5—C6	174.27 (11)	O1—N3—C15—C14	−5.76 (16)
C4—C5—C6—C7	−76.56 (15)	C14—C15—C16—C17	−0.04 (17)
C5—C6—C7—C8	−73.64 (15)	N3—C15—C16—C17	179.32 (10)
C6—C7—C8—C9	165.98 (11)	C15—C16—C17—C18	−0.80 (18)
C7—C8—C9—C10	−59.54 (15)	C15—C16—C17—N4	176.53 (11)
C8—C9—C10—C11	−42.72 (16)	O3—N4—C17—C16	6.15 (17)
C9—C10—C11—C12	−176.67 (11)	O4—N4—C17—C16	−172.37 (11)
C10—C11—C12—C13	−164.47 (10)	O3—N4—C17—C18	−176.45 (11)
C11—C12—C13—C1	61.91 (14)	O4—N4—C17—C18	5.03 (16)
N2—N1—C1—C2	−178.08 (10)	C16—C17—C18—C19	1.02 (18)
N1—C1—C2—C3	−18.92 (16)	N4—C17—C18—C19	−176.30 (11)
N1—C1—C13—C12	73.25 (16)	C17—C18—C19—C14	−0.40 (18)
N1—N2—C14—C19	2.39 (16)	N2—C14—C19—C18	179.95 (11)
N1—N2—C14—C15	−177.24 (10)	C15—C14—C19—C18	−0.39 (17)
N2—C14—C15—C16	−179.74 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2N···O1	0.899 (15)	1.961 (15)	2.6302 (14)	129.9 (12)
C7—H7A···O3^i	0.99	2.54	3.4363 (18)	150

Symmetry code: (i) −x+2, −y+2, −z+1.