Structure and packing of aminoxyl and piperidinyl acryl­amide monomers

The closely related title compounds, 4-acryl­amido-2,2,6,6-tetra­methyl­piper­idine-1-oxyl, C₁₂H₂₁N₂O₂, (I), and N-(2,2,6,6-tetra­methyl­piperidin-4-yl)acryl­amide monohydrate, C₁₂H₂₂N₂O·H₂O, (II), are important monomers in the preparation of redox-active polymers. They comprise an acryl­amide group of the usual s-cis configuration appended to a 2,2,6,6-tetra­methyl-substituted piperidine-1-oxyl radical or a piperidinyl chair, respectively. The adjacent amide and piperidinyl H atoms are approximately trans across the C—N bond. The packing in (I) is dominated by N—H...O hydrogen bonds; these are supported by C—H...O contacts to form an R₂¹(6) ring repeat, a motif which has been observed in other acryl­amide structures. In (II), hydrogen bonds are again key to the packing arrangements. In this case, the incorporated solvent water mol­ecule acts as an acceptor through its O atom and as a donor through both H atoms, binding three adjacent piperidinylacryl­amide mol­ecules into layers. In both structures, weak C—H...O contacts involving the piperidinyl methyl H atoms and a proximal acryl­amide carbonyl O atom extend the structure in the third dimension.

S1. Introduction

The stable aminoxyl radical TEMPO (2,2,6,6-tetra­methyl­piperidine-1-oxyl) and its derivatives have received much attention due to their usefulness in synthesis and a wide variety of practical applications (Crich, 2008). They have been employed extensively as mild oxidants for alcohols, often in catalytic qu­anti­ties (Gheorghe et al., 2006; Tojo & Fernández, 2007; Tebben & Studer, 2011), and as radical traps in biological science, and in molecular and polymer synthesis (Conte et al., 2009; Pattison et al., 2012; Hyslop & Parent, 2012). The polymer sub-discipline of nitroxide-mediated polymerization (NMP) derives its name from this class of compounds (Tebben & Studer, 2011). Other applications include use as a paramagnetic probe for EPR studies (Ricci et al., 2011), as a spin label in NMR (Jahnke et al., 2000, 2001), as a photostabilizer (Beaton & Argyropoulos, 2001) and as a synergist with anti­neoplastic agents (Ba & Ma­thias, 2011). In addition, the Nishide group have successfully utilized aminoxyl radicals as the cathode in organic rechargeable batteries (Nishide et al., 2009; Koshika et al., 2010).

Our primary inter­est in TEMPO derivatives is as redox-active subunits in polymer gel actuators (Goswami et al., 2013). During the course of this work, we have reported the structures of TEMPO-type complexes and their respective precursors (see, for example, Goswami et al., 2011, 2014, 2015). Recently, we prepared crystalline samples of both TEMPO acryl­amide, (I), and its piperidinyl analogue, (II) (see scheme). We report here their molecular structures and packing arrangements.

The TEMPO HC(CH₂)₂(CMe₂)₂NO radical skeleton appears in more than 200 structures recorded in the Cambridge Structural Database (CSD, [Version?]; Groom & Allen, 2014). Inter­est in the crystal packing of such species derives from the fact that they often display inter­molecular ferromagnetic inter­actions at extremely low temperatures, and the packing features in such materials show considerable similarities (Kajiwara et al., 1995; Iwasaki, Yoshikawa, Yamamoto, Kan-nari et al., 1999; Iwasaki, Yoshikawa, Yamamoto, Takada et al., 1999). Structures of compounds with a secondary amide substituent at the TEMPO 4-position are somewhat less plentiful, with 30 discrete examples in the CSD, ranging from the simple 4-acetamide-2,2,6,6-tetra­methyl-piperidine-1-oxyl (CSD refcode UDOMUW; Yonekuta et al., 2007) to more complex compounds, e.g. the TEMPO dimer [EQUKIK; trans-N,N'-bis­(2,2,6,6-tetra­methyl­piperidin-4-yl N-oxide)oxamide; Sommer et al., 2003], the fluorenyl derivative {AHIBEZ; 4-[(9H-fluoren-9-yl)(9H-fluoren-9-yl­idene)methyl]-N-(1-oxyl-2,2,6,6-tetra­methyl­piperidin-4-yl)benzamide capable of forming a biradical species; Dane et al., 2009}, and various organometallic examples (Qiu et al., 2009; Yi et al., 2011).

A CSD search for 2,2,6,6-tetra­methyl­piperidines turns up many protonated or metal-coordinated quaternary examples, but the neutral amine is not common, registering only 12 hits. Of these, 4-amido derivatives are represented by succinic di­amide (MPLSCA; Ruben et al., 1974) and oxalamide (MEFGIO; McFarland et al., 2006) structures.

A search for structures with the acryl­amide functional group reveals 44 unique molecules, 13 of which are found in metal complexes. These include acryl­amide itself (Zhou et al., 2007; Udovenko & Kolzunova, 2008) and N-(1-acryloyl-2,2,6,6-tetra­methyl­piperidin-4-yl)acryl­amide (Goswami et al., 2011), a close relative of the acryl­amide derivatives reported here.

S2. Experimental

S2.1. Synthesis and crystallization

2,2,6,6-Tetra­methyl-4-acryl­amido-1-piperidine-1-oxyl, (I), was synthesized using modifications (Gheorghe et al., 2006) to the original procedure of Rozantsev & Suskina (1968) (Fig. 1). To a stirred suspension of NaH (2 equivalents) in dry di­methyl­formamide (DMF, 100 ml) at 273 K, 4-amino-2,2,6,6-tetra­methyl­piperidine-1-oxyl (TEMPO-NH₂, 1 equivalent) was added in small portions. The reaction mixture was then stirred at room temperature for 30 min, with the visible evolution of hydrogen gas. Acryloyl chloride (2 equivalents) was added dropwise at 273 K. The resulting mixture was stirred for 3 h at room temperature, after which water (100 ml) was added and the solution extracted with EtOAc (2 × 50 ml). The organic phase was washed with water (2 × 50 ml), dried over anhydrous MgSO₄, filtered, evaporated under reduced pressure and purified by column chromatography (silica gel, 10% EtOAc in hexane) to give (I) as a dark-orange solid. Recrystallization from EtOAc gave near-colourless plates of (I) (72% yield).

N-(2,2,6,6-Tetra­methyl­piperidin-4-yl)acryl­amide, (II), was synthesized according to the procedure of Nishide and co-workers (Koshika et al., 2010), an updated version of the method of Karrer (1980) (Fig. 1). Recrystallization of the acryl­amide monomer from methanol gave colourless blocks of (II).

S2.2. Analytical data

For (I): m.p. 321–322 K; IR (ATR, ν, cm^-1): 1657 (C═O), 1636 (C═C); microanalysis, calculated: C 63.97, H 9.39, N 12.43%; found: C 63.55, H 9.44, N 11.96%; HRMS (ESI⁺), calculated for C₁₂H₂₁NaNO₂: 248.1491; found: 248.1495 [M]⁺.

For (II): m.p. 381–383 K; IR (ATR, ν, cm^-1): 1659 (C═O), 1625 (C═ C); ¹H NMR (400 MHz, CDCl₃, δ, p.p.m.): 6.25 (1H, dd, J = 1 and 17 Hz, –CH═CH_trans), 6.07 (1H, dd, J = 11 and 17 Hz, –CH═CH₂), 6.06 (1H, br, amide NH), 5.60 (1H, dd, J = 1 and 11 Hz, –CH═CH_cis), 4.34 (1H, m, piperidine CH), 3.24 (1H, br, amine NH), 1.88 (2H, dd, J = 4 and 13 Hz, piperidine CH₂), 1.32 (6H, s, 2 × CH₃), 1.22 (6H, s, 2 × CH₃); ¹³C NMR (400 MHz, CDCl₃, δ, p.p.m.): 164.9 (C═ O), 131.0 (–CH═), 126.2 (═CH₂), 51.3, 44.8, 42.4, [34.6 and 28.2 (CH₃)]; HRMS (ESI⁺), calculated for C₁₂H₂₂NaN₂O: 234.1464; found: 234.1476 [M]⁺.

S2.3. Refinement

Crystal data, data collection and structure refinement details are summarised in Table 1. The H atoms on N1 for (I), and on N1, N4 and O1W for (II), were located in difference Fourier maps and their coordinates were refined, with U_iso(H) = 1.2U_eq(N) and 1.5U_eq(O). All H atoms bound to C atoms were refined using a riding model, with C—H = 0.95 Å for vinyl H atoms, 1.00 Å for C—H and 0.99 Å for CH₂ H atoms, all with U_iso(H) = 1.2U_eq(C), and with C—H = 0.98 Å and U_iso(H) = 1.5U_eq(C) for CH₃ H atoms. For (II), ISOR [Please rephrase using non-software-specific terms] restraints were applied to atoms N1, N4, O7 and C2–C9 to prevent them appearing as nonpositive definite.

S3. Results and discussion

S3.1. Molecular structures of (I) and (II)

The molecular structures of (I) and (II) (Figs. 2a and 2b) are sufficiently similar to be discussed together. The piperidine rings each adopt chair conformations, with two methyl substituents on each of atoms C2 and C6. An oxyl substituent on atom N1 of (I) generates the classical TEMPO skeleton (Lebedev & Kaza­rnovskii, 1960) from the precursor piperidine (II). The C4 acryl­amide substituents complete their structural units. The relative conformations of the acryl­amide C═O and vinyl double bonds are the usual s-cis; O7—C7—C8—C9 torsion angles = 3.59 (17)° for (I) and 16.3 (2)° for (II). This compares with Vista (Groom & Allen, 2014) results for acryl­amide O═C—C═C torsion angles; median value = 4.443° over 134 observations.

There is a noticeable similarity in the geometry of the acryl­amide residues with respect to the piperidinyl rings for (I) and (II). Illustrating this, the C7—N—C4—C3 torsion angles (see Fig. 3) for (I) and (II) are 91.74 (11) and 89.16 (14)°, respectively. This trans spatial arrangement of the piperidinyl and amide H atoms appears common for TEMPO secondary amides, for example, 4-acetamide-2,2,6,6-tetra­methyl­piperidine-1-oxyl (torsion angle = 91.23°; CSD refcode UDOMUW; Yonekuta et al., 2007), 4-[(9H-fluoren-9-yl)(9H-fluoren-9-yl­idene)methyl]- N-(1-oxyl-2,2,6,6-tetra­methyl­piperidin-4-yl)benzamide acetone solvate (torsion angle = 91.34°; CSD refcode AHIBEZ; Dane et al., 2009), and the two piperidinyl examples in the CSD, i.e. N-(4-bromo­phenyl)-N'-(2,2,6,6-tetra­methyl-4-piperidinyl)oxalamide (torsion angle = 97.61°; CSD refcode MEFGIO; McFarland et al., 2006) and N,N'-bis­(2,2,6,6-tetra­methyl­piperidyl-4)succinic acid di­amide dehydrate (torsion angle = 99.14°; CSD refcode MPLSCA; Ruben et al., 1974). The similarity also extends to the closely related TEMPO acrylate, namely 4-acryloyl­oxy-2,2,6,6-tetra­methyl­piperidine-1-oxyl (refcode LUFQIO00), and methacrylate, namely 4-methacryloyl­oxy-2,2,6,6-tetra­methyl­piperidine-1-oxyl, (refcode LUFQOU00) (Goswami et al., 2015), with equivalent torsion angles of 84.78 (13) and 83.1 (3)°, respectively.

Bond lengths (Allen et al., 1987) and angles are normal in both molecules and compare well with those found in closely related structures (Goswami et al., 2011, 2014). Compound (II) crystallizes with a water solvent molecule in the asymmetric unit, linked to the organic molecule via an N—H···O hydrogen bond from the acryl­amide substituent.

S3.2. Packing for (I)

For (I), a C(4) chain (Bernstein et al., 1995) of classical N4—H4N···O7 hydrogen bonds, supported by C8—H8···O7 contacts, links adjacent acryl­amide substituents (Table 2). These contacts, with atom O7 acting as a bifurcated acceptor, generate an R₂¹(6) ring (Bernstein et al., 1995) repeat structure that stacks the molecules along c. Within this chain, the molecules flip-flop in an approximately head-to-tail fashion, with a dihedral angle of 146.51° between adjacent R₂¹(6) ring planes (Fig. 4). Similar chain propagation with the formation of six-membered rings has been observed for other acryl­amide structures [N-(2-hy­droxy­methyl)-1,3-di­hydroxy-2-propyl)­acrylamic acid (refcode YOXBAO; Oddon et al., 1995) and N-tert-butyl­acryl­amide (refcode CEDXUE01; Kashino et al., 1994)]. However, in these examples, the rings form between near-orthogonal molecules (the dihedral angles between ring motifs are 104.35° for YOXBAO and 107.44° for CEDXUE01). In the bis­(2-acryl­amido-2-methyl­propane-1-sulfonate) salt (refcode JAVQON; Ribot et al., 2005), by contrast, the R₂¹(6) motif propagates through the structure in a helical fashion.

The former packing motif does not result in any close contacts between the nitroxide O1 atoms. Indeed the closest inter­molecular contacts involving O1 are two very weak nonclassical C61—H61C···O1 and C22—H22A···O1 hydrogen bonds that compose R₂²(10) rings and bridge the chains formed by the R₂¹(6) repeat. The overall effect is the formation of layers in the bc plane (Fig. 5). Close and almost orthogonal contacts between nitroxide groups [O1···O1 = 4.184 (3) Å] have been implicated as a possible cause of ferromagnetic exchange reactions in TEMPO systems (Griesar et al., 1997, 2000). In (I), the shortest O···O contact distances are significantly longer [O1···O1ⁱⁱⁱ = 4.945 (2) Å; symmetry code: (iii) x, -y + 1/2, z - 1/2] and the NO functional groups are not orthogonal. Finally, additional weak C21—H21B···O7 contacts form zigzag C(8) chains along b (Fig. 6) and inter­connect the layers of molecules to generate a three-dimensional network.

S3.3. Packing for (II)

The crystal structure of (II) contrasts sharply with that of (I), with the water solvent molecule playing a seminal role in the overall packing framework. Each water molecule acts as an acceptor in a classical N2—H2N···O1W hydrogen bond, and as a donor in O1W—H1W···O7 and O1W—H2W···N1 hydrogen bonds (Table 3). These contacts bind adjacent trios of molecules into a two-dimensional layer in the bc plane (Fig. 7). Weak C21—H21C···O7 contacts form inversion dimers enclosing R₂²(16) loops. These weaker contacts also link parallel layers of molecules, resulting in a three-dimensional network of molecules stacked along the b axis.

Computing details

For both compounds, data collection: CrysAlis PRO (Agilent, 2013); cell refinement: CrysAlis PRO (Agilent, 2013); data reduction: CrysAlis PRO (Agilent, 2013). Program(s) used to solve structure: SHELXS97 (Sheldrick, 2008) and TITAN (Hunter & Simpson, 1999) for (I); SIR2011 (Burla et al., 2012) for (II). For both compounds, program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015) and TITAN (Hunter & Simpson, 1999); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015), enCIFer (Allen et al., 2004) and publCIF (Westrip, 2010).

Figures

	Fig. 1. The synthesis of (I) and (II), and their place in the synthesis of electro-active polymers. FRP = free radical polymerization.
	Fig. 2. The molecular structures of (a) (I) and (b) (II), with the atom-numbering schemes. Displacement ellipsoids are drawn at the 50% probability level. The intermolecular hydrogen bond from (II) to the water solvent molecule in the asymmetric unit is drawn as a dashed line.
	Fig. 3. A Newman projection of the typical geometry of the acrylamide residue with respect to the piperidinyl ring (CSD results from 34 observations), and that observed for (I), viewed down the N4—C4 bond. The C7—N4—C4—C3 torsion (see text) is coloured red.
	Fig. 4. The chains of molecules of (I), running along the c axis. Intermolecular hydrogen bonds are drawn as turquoise lines.
	Fig. 5. The sheets of molecules of (I), in the bc plane. Intermolecular hydrogen bonds are drawn as turquoise lines. A representative intermolecular O1···O1 contact is shown as a green dotted line. [Perhaps not sufficient contrast between these two colours. Please consider alternatives.]
	Fig. 6. The zigzag chains of molecules of (I), along the b axis. Intermolecular hydrogen bonds are drawn as turquoise lines.
	Fig. 7. The layers of molecules of (II), in the bc plane. Intermolecular hydrogen bonds are drawn as turquoise lines.

(I) 4-Acrylamido-2,2,6,6-tetramethylpiperidine-1-oxyl

Crystal data

C12H21N2O2	F(000) = 492
Mr = 225.31	Dx = 1.197 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54184 Å
a = 11.5408 (2) Å	Cell parameters from 7507 reflections
b = 11.7953 (2) Å	θ = 4.1–74.2°
c = 9.7964 (2) Å	µ = 0.66 mm^−1
β = 110.299 (2)°	T = 100 K
V = 1250.74 (4) Å^3	Plate, colourless
Z = 4	0.27 × 0.11 × 0.05 mm

Data collection

Agilent SuperNova Dual Source diffractometer with an Atlas detector	2516 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	2275 reflections with I > 2σ(I)
Detector resolution: 5.1725 pixels mm^-1	Rint = 0.030
ω scans	θmax = 74.3°, θmin = 4.1°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2013)	h = −14→14
Tmin = 0.752, Tmax = 1.000	k = −14→14
12123 measured reflections	l = −12→11

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.034	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.087	w = 1/[σ^2(Fo^2) + (0.0381P)^2 + 0.5066P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
2516 reflections	Δρmax = 0.29 e Å^−3
152 parameters	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.

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

	x	y	z	Uiso*/Ueq
O1	0.31052 (7)	0.22108 (6)	0.21433 (8)	0.01809 (19)
N1	0.29372 (8)	0.32826 (7)	0.19092 (9)	0.01345 (19)
C2	0.18232 (9)	0.37682 (9)	0.21515 (11)	0.0141 (2)
C21	0.07153 (10)	0.30350 (10)	0.13045 (13)	0.0205 (2)
H21A	0.0643	0.3007	0.0278	0.031*
H21B	−0.0039	0.3362	0.1384	0.031*
H21C	0.0832	0.2266	0.1707	0.031*
C22	0.20027 (10)	0.37189 (10)	0.37769 (12)	0.0191 (2)
H22A	0.2239	0.2948	0.4141	0.029*
H22B	0.1229	0.3927	0.3916	0.029*
H22C	0.2655	0.4250	0.4312	0.029*
C3	0.16081 (9)	0.49824 (9)	0.15770 (11)	0.0142 (2)
H3A	0.1262	0.4961	0.0501	0.017*
H3B	0.0987	0.5344	0.1923	0.017*
C4	0.27737 (9)	0.57099 (9)	0.20451 (11)	0.0139 (2)
H4	0.3128	0.5743	0.3132	0.017*
C5	0.37062 (9)	0.51704 (9)	0.14639 (11)	0.0153 (2)
H5A	0.4463	0.5642	0.1760	0.018*
H5B	0.3359	0.5169	0.0387	0.018*
C6	0.40608 (9)	0.39531 (9)	0.19946 (11)	0.0138 (2)
C61	0.46605 (10)	0.33808 (10)	0.10064 (12)	0.0182 (2)
H61A	0.4882	0.2599	0.1332	0.027*
H61B	0.5406	0.3799	0.1051	0.027*
H61C	0.4078	0.3377	0.0003	0.027*
C62	0.49624 (10)	0.39249 (10)	0.35735 (11)	0.0174 (2)
H62A	0.4563	0.4253	0.4216	0.026*
H62B	0.5702	0.4365	0.3650	0.026*
H62C	0.5197	0.3138	0.3862	0.026*
N4	0.24829 (8)	0.68545 (8)	0.14626 (10)	0.0144 (2)
H4N	0.2418 (12)	0.6979 (11)	0.0576 (15)	0.017*
C7	0.21800 (9)	0.76929 (9)	0.22023 (11)	0.0137 (2)
O7	0.21901 (7)	0.75780 (7)	0.34628 (8)	0.01844 (19)
C8	0.18506 (10)	0.87821 (9)	0.13881 (12)	0.0169 (2)
H8	0.1812	0.8809	0.0404	0.020*
C9	0.16111 (11)	0.97081 (10)	0.19932 (13)	0.0235 (3)
H9A	0.1646	0.9694	0.2976	0.028*
H9B	0.1404	1.0390	0.1447	0.028*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0211 (4)	0.0124 (4)	0.0212 (4)	0.0017 (3)	0.0080 (3)	0.0004 (3)
N1	0.0145 (4)	0.0120 (4)	0.0143 (4)	0.0003 (3)	0.0057 (3)	−0.0005 (3)
C2	0.0138 (5)	0.0143 (5)	0.0159 (5)	0.0004 (4)	0.0073 (4)	0.0002 (4)
C21	0.0160 (5)	0.0168 (5)	0.0287 (6)	−0.0014 (4)	0.0076 (5)	−0.0016 (4)
C22	0.0224 (5)	0.0203 (6)	0.0183 (5)	0.0022 (4)	0.0118 (4)	0.0038 (4)
C3	0.0142 (5)	0.0140 (5)	0.0148 (5)	0.0007 (4)	0.0058 (4)	0.0008 (4)
C4	0.0171 (5)	0.0126 (5)	0.0124 (5)	0.0002 (4)	0.0059 (4)	0.0014 (4)
C5	0.0160 (5)	0.0159 (5)	0.0158 (5)	−0.0008 (4)	0.0076 (4)	0.0008 (4)
C6	0.0129 (5)	0.0162 (5)	0.0130 (5)	−0.0005 (4)	0.0054 (4)	−0.0008 (4)
C61	0.0183 (5)	0.0211 (6)	0.0174 (5)	0.0018 (4)	0.0090 (4)	−0.0020 (4)
C62	0.0157 (5)	0.0210 (6)	0.0147 (5)	0.0000 (4)	0.0044 (4)	−0.0014 (4)
N4	0.0196 (4)	0.0136 (5)	0.0112 (4)	−0.0002 (3)	0.0069 (3)	0.0015 (3)
C7	0.0114 (5)	0.0152 (5)	0.0146 (5)	−0.0024 (4)	0.0049 (4)	−0.0009 (4)
O7	0.0235 (4)	0.0203 (4)	0.0140 (4)	0.0015 (3)	0.0097 (3)	0.0008 (3)
C8	0.0191 (5)	0.0170 (5)	0.0163 (5)	−0.0013 (4)	0.0080 (4)	0.0014 (4)
C9	0.0324 (6)	0.0182 (6)	0.0233 (6)	0.0033 (5)	0.0137 (5)	0.0027 (4)

Geometric parameters (Å, º)

O1—N1	1.2875 (12)	C5—H5A	0.9900
N1—C6	1.4962 (13)	C5—H5B	0.9900
N1—C2	1.4996 (13)	C6—C61	1.5286 (14)
C2—C3	1.5273 (14)	C6—C62	1.5361 (14)
C2—C21	1.5281 (15)	C61—H61A	0.9800
C2—C22	1.5339 (15)	C61—H61B	0.9800
C21—H21A	0.9800	C61—H61C	0.9800
C21—H21B	0.9800	C62—H62A	0.9800
C21—H21C	0.9800	C62—H62B	0.9800
C22—H22A	0.9800	C62—H62C	0.9800
C22—H22B	0.9800	N4—C7	1.3419 (14)
C22—H22C	0.9800	N4—H4N	0.859 (14)
C3—C4	1.5258 (14)	C7—O7	1.2383 (13)
C3—H3A	0.9900	C7—C8	1.4903 (15)
C3—H3B	0.9900	C8—C9	1.3170 (16)
C4—N4	1.4588 (13)	C8—H8	0.9500
C4—C5	1.5207 (14)	C9—H9A	0.9500
C4—H4	1.0000	C9—H9B	0.9500
C5—C6	1.5336 (14)
O1—N1—C6	115.79 (8)	C6—C5—H5A	108.8
O1—N1—C2	115.54 (8)	C4—C5—H5B	108.8
C6—N1—C2	124.28 (8)	C6—C5—H5B	108.8
N1—C2—C3	109.78 (8)	H5A—C5—H5B	107.7
N1—C2—C21	107.44 (8)	N1—C6—C61	107.77 (8)
C3—C2—C21	109.40 (9)	N1—C6—C5	110.59 (8)
N1—C2—C22	109.60 (8)	C61—C6—C5	108.97 (8)
C3—C2—C22	111.35 (9)	N1—C6—C62	108.42 (8)
C21—C2—C22	109.17 (9)	C61—C6—C62	109.32 (8)
C2—C21—H21A	109.5	C5—C6—C62	111.68 (9)
C2—C21—H21B	109.5	C6—C61—H61A	109.5
H21A—C21—H21B	109.5	C6—C61—H61B	109.5
C2—C21—H21C	109.5	H61A—C61—H61B	109.5
H21A—C21—H21C	109.5	C6—C61—H61C	109.5
H21B—C21—H21C	109.5	H61A—C61—H61C	109.5
C2—C22—H22A	109.5	H61B—C61—H61C	109.5
C2—C22—H22B	109.5	C6—C62—H62A	109.5
H22A—C22—H22B	109.5	C6—C62—H62B	109.5
C2—C22—H22C	109.5	H62A—C62—H62B	109.5
H22A—C22—H22C	109.5	C6—C62—H62C	109.5
H22B—C22—H22C	109.5	H62A—C62—H62C	109.5
C4—C3—C2	113.76 (8)	H62B—C62—H62C	109.5
C4—C3—H3A	108.8	C7—N4—C4	122.58 (9)
C2—C3—H3A	108.8	C7—N4—H4N	118.2 (9)
C4—C3—H3B	108.8	C4—N4—H4N	118.8 (9)
C2—C3—H3B	108.8	O7—C7—N4	122.94 (10)
H3A—C3—H3B	107.7	O7—C7—C8	122.71 (10)
N4—C4—C5	109.72 (8)	N4—C7—C8	114.34 (9)
N4—C4—C3	110.10 (8)	C9—C8—C7	121.91 (10)
C5—C4—C3	108.47 (8)	C9—C8—H8	119.0
N4—C4—H4	109.5	C7—C8—H8	119.0
C5—C4—H4	109.5	C8—C9—H9A	120.0
C3—C4—H4	109.5	C8—C9—H9B	120.0
C4—C5—C6	113.90 (8)	H9A—C9—H9B	120.0
C4—C5—H5A	108.8
O1—N1—C2—C3	−169.83 (8)	C2—N1—C6—C61	−152.56 (9)
C6—N1—C2—C3	34.76 (12)	O1—N1—C6—C5	171.10 (8)
O1—N1—C2—C21	−50.95 (11)	C2—N1—C6—C5	−33.55 (12)
C6—N1—C2—C21	153.64 (9)	O1—N1—C6—C62	−66.14 (11)
O1—N1—C2—C22	67.56 (11)	C2—N1—C6—C62	89.22 (11)
C6—N1—C2—C22	−87.85 (11)	C4—C5—C6—N1	44.29 (11)
N1—C2—C3—C4	−46.86 (11)	C4—C5—C6—C61	162.58 (9)
C21—C2—C3—C4	−164.53 (9)	C4—C5—C6—C62	−76.55 (11)
C22—C2—C3—C4	74.70 (11)	C5—C4—N4—C7	−148.95 (9)
C2—C3—C4—N4	−179.45 (8)	C3—C4—N4—C7	91.74 (11)
C2—C3—C4—C5	60.48 (11)	C4—N4—C7—O7	4.10 (15)
N4—C4—C5—C6	−179.11 (8)	C4—N4—C7—C8	−176.89 (9)
C3—C4—C5—C6	−58.80 (11)	O7—C7—C8—C9	3.59 (17)
O1—N1—C6—C61	52.08 (11)	N4—C7—C8—C9	−175.42 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4N···O7^i	0.859 (14)	2.061 (14)	2.9171 (11)	174.7 (13)
C8—H8···O7^i	0.95	2.66	3.4233 (13)	138
C21—H21B···O7^ii	0.98	2.70	3.4808 (13)	137
C61—H61C···O1^iii	0.98	2.72	3.6494 (13)	158
C22—H22A···O1^iv	0.98	2.76	3.2842 (13)	114

Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x, y−1/2, −z+1/2; (iii) x, −y+1/2, z−1/2; (iv) x, −y+1/2, z+1/2.

(II) N-(2,2,6,6-Tetramethylpiperidin-4-yl)acrylamide monohydrate

Crystal data

C12H22N2O·H2O	F(000) = 504
Mr = 228.33	Dx = 1.138 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54184 Å
a = 11.9763 (3) Å	Cell parameters from 6993 reflections
b = 10.3132 (2) Å	θ = 5.9–76.7°
c = 11.8550 (3) Å	µ = 0.62 mm^−1
β = 114.527 (3)°	T = 100 K
V = 1332.12 (6) Å^3	Block, colourless
Z = 4	0.14 × 0.10 × 0.07 mm

Data collection

Agilent SuperNova Dual Source diffractometer with an Atlas detector	2777 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	2442 reflections with I > 2σ(I)
Detector resolution: 5.1725 pixels mm^-1	Rint = 0.085
ω scans	θmax = 77.0°, θmin = 4.1°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2013)	h = −15→15
Tmin = 0.262, Tmax = 1.000	k = −12→10
14047 measured reflections	l = −14→14

Refinement

Refinement on F^2	90 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.057	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.137	w = 1/[σ^2(Fo^2) + (0.0758P)^2 + 0.5327P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
2777 reflections	Δρmax = 0.40 e Å^−3
161 parameters	Δρmin = −0.39 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.

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

	x	y	z	Uiso*/Ueq
N1	0.23575 (10)	0.81721 (11)	0.31083 (10)	0.0125 (3)
H1N	0.2568 (16)	0.8522 (19)	0.2538 (17)	0.015*
C2	0.34171 (11)	0.73387 (14)	0.38824 (12)	0.0134 (3)
C21	0.45717 (12)	0.81265 (15)	0.41063 (13)	0.0188 (3)
H21A	0.4549	0.8944	0.4518	0.028*
H21B	0.4607	0.8311	0.3311	0.028*
H21C	0.5299	0.7629	0.4633	0.028*
C22	0.34041 (13)	0.70649 (15)	0.51496 (12)	0.0192 (3)
H22A	0.2756	0.6437	0.5050	0.029*
H22B	0.3248	0.7873	0.5495	0.029*
H22C	0.4200	0.6710	0.5713	0.029*
C3	0.34483 (11)	0.60693 (13)	0.32152 (11)	0.0132 (3)
H3A	0.3730	0.6262	0.2557	0.016*
H3B	0.4054	0.5476	0.3817	0.016*
C4	0.22048 (11)	0.53796 (13)	0.26314 (11)	0.0128 (3)
H4	0.1961	0.5091	0.3303	0.015*
C5	0.12308 (11)	0.63024 (14)	0.17619 (11)	0.0138 (3)
H5A	0.0425	0.5858	0.1423	0.017*
H5B	0.1435	0.6527	0.1058	0.017*
C6	0.11321 (11)	0.75585 (14)	0.24203 (12)	0.0133 (3)
C61	0.03636 (12)	0.85551 (15)	0.14536 (13)	0.0193 (3)
H61A	0.0755	0.8744	0.0892	0.029*
H61B	0.0303	0.9354	0.1872	0.029*
H61C	−0.0461	0.8205	0.0977	0.029*
C62	0.04944 (12)	0.72972 (15)	0.32824 (13)	0.0183 (3)
H62A	0.0502	0.8089	0.3743	0.027*
H62B	0.0929	0.6605	0.3866	0.027*
H62C	−0.0356	0.7031	0.2789	0.027*
N4	0.23031 (10)	0.42488 (12)	0.19380 (10)	0.0138 (3)
H4N	0.2294 (16)	0.4362 (19)	0.1236 (18)	0.017*
C7	0.26296 (11)	0.30766 (13)	0.24637 (12)	0.0128 (3)
O7	0.27586 (9)	0.28280 (10)	0.35350 (9)	0.0165 (2)
C8	0.28484 (12)	0.20925 (14)	0.16549 (13)	0.0165 (3)
H8	0.2542	0.2242	0.0788	0.020*
C9	0.34633 (14)	0.10151 (15)	0.21287 (15)	0.0224 (3)
H9A	0.3773	0.0859	0.2995	0.027*
H9B	0.3596	0.0397	0.1603	0.027*
O1W	0.21928 (10)	0.45323 (11)	−0.05444 (10)	0.0214 (3)
H1W	0.240 (2)	0.390 (2)	−0.088 (2)	0.032*
H2W	0.2273 (19)	0.525 (2)	−0.097 (2)	0.032*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0152 (5)	0.0063 (5)	0.0156 (5)	0.0010 (4)	0.0061 (4)	0.0005 (4)
C2	0.0147 (5)	0.0088 (6)	0.0154 (5)	0.0011 (4)	0.0050 (4)	−0.0002 (4)
C21	0.0173 (6)	0.0109 (7)	0.0252 (6)	−0.0013 (5)	0.0056 (5)	−0.0019 (5)
C22	0.0258 (6)	0.0148 (7)	0.0162 (6)	0.0026 (5)	0.0080 (5)	0.0003 (5)
C3	0.0149 (5)	0.0085 (6)	0.0156 (5)	0.0016 (4)	0.0059 (4)	0.0003 (4)
C4	0.0173 (5)	0.0065 (6)	0.0153 (5)	0.0002 (4)	0.0076 (4)	−0.0004 (4)
C5	0.0155 (5)	0.0097 (6)	0.0153 (5)	0.0005 (4)	0.0055 (4)	−0.0010 (4)
C6	0.0141 (5)	0.0088 (6)	0.0162 (5)	0.0007 (4)	0.0057 (4)	−0.0009 (4)
C61	0.0202 (6)	0.0126 (7)	0.0215 (6)	0.0058 (5)	0.0051 (5)	0.0010 (5)
C62	0.0199 (6)	0.0150 (7)	0.0227 (6)	0.0007 (5)	0.0116 (5)	−0.0018 (5)
N4	0.0203 (5)	0.0074 (5)	0.0155 (5)	0.0004 (4)	0.0091 (4)	0.0001 (4)
C7	0.0135 (5)	0.0075 (6)	0.0172 (5)	−0.0017 (4)	0.0062 (4)	−0.0003 (4)
O7	0.0243 (5)	0.0072 (5)	0.0185 (5)	0.0015 (4)	0.0093 (4)	0.0015 (3)
C8	0.0205 (5)	0.0103 (6)	0.0199 (5)	−0.0025 (4)	0.0094 (4)	−0.0022 (4)
C9	0.0309 (7)	0.0092 (7)	0.0315 (7)	0.0017 (5)	0.0174 (6)	−0.0010 (5)
O1W	0.0394 (6)	0.0074 (6)	0.0240 (5)	0.0024 (4)	0.0199 (5)	0.0014 (4)

Geometric parameters (Å, º)

N1—C2	1.4914 (16)	C5—H5B	0.9900
N1—C6	1.4918 (16)	C6—C61	1.5300 (18)
N1—H1N	0.891 (19)	C6—C62	1.5325 (18)
C2—C21	1.5291 (18)	C61—H61A	0.9800
C2—C22	1.5350 (18)	C61—H61B	0.9800
C2—C3	1.5380 (19)	C61—H61C	0.9800
C21—H21A	0.9800	C62—H62A	0.9800
C21—H21B	0.9800	C62—H62B	0.9800
C21—H21C	0.9800	C62—H62C	0.9800
C22—H22A	0.9800	N4—C7	1.3418 (18)
C22—H22B	0.9800	N4—H4N	0.84 (2)
C22—H22C	0.9800	C7—O7	1.2408 (17)
C3—C4	1.5320 (17)	C7—C8	1.4921 (19)
C3—H3A	0.9900	C8—C9	1.323 (2)
C3—H3B	0.9900	C8—H8	0.9500
C4—N4	1.4595 (17)	C9—H9A	0.9500
C4—C5	1.5267 (17)	C9—H9B	0.9500
C4—H4	1.0000	O1W—H1W	0.85 (3)
C5—C6	1.5421 (19)	O1W—H2W	0.93 (2)
C5—H5A	0.9900
C2—N1—C6	118.99 (11)	C6—C5—H5A	109.1
C2—N1—H1N	105.3 (11)	C4—C5—H5B	109.1
C6—N1—H1N	106.3 (11)	C6—C5—H5B	109.1
N1—C2—C21	106.13 (11)	H5A—C5—H5B	107.9
N1—C2—C22	110.88 (11)	N1—C6—C61	105.90 (11)
C21—C2—C22	107.68 (11)	N1—C6—C62	111.06 (11)
N1—C2—C3	111.73 (10)	C61—C6—C62	107.83 (11)
C21—C2—C3	109.16 (11)	N1—C6—C5	111.61 (10)
C22—C2—C3	111.04 (11)	C61—C6—C5	109.51 (11)
C2—C21—H21A	109.5	C62—C6—C5	110.73 (11)
C2—C21—H21B	109.5	C6—C61—H61A	109.5
H21A—C21—H21B	109.5	C6—C61—H61B	109.5
C2—C21—H21C	109.5	H61A—C61—H61B	109.5
H21A—C21—H21C	109.5	C6—C61—H61C	109.5
H21B—C21—H21C	109.5	H61A—C61—H61C	109.5
C2—C22—H22A	109.5	H61B—C61—H61C	109.5
C2—C22—H22B	109.5	C6—C62—H62A	109.5
H22A—C22—H22B	109.5	C6—C62—H62B	109.5
C2—C22—H22C	109.5	H62A—C62—H62B	109.5
H22A—C22—H22C	109.5	C6—C62—H62C	109.5
H22B—C22—H22C	109.5	H62A—C62—H62C	109.5
C4—C3—C2	113.64 (10)	H62B—C62—H62C	109.5
C4—C3—H3A	108.8	C7—N4—C4	122.31 (11)
C2—C3—H3A	108.8	C7—N4—H4N	118.0 (13)
C4—C3—H3B	108.8	C4—N4—H4N	118.6 (14)
C2—C3—H3B	108.8	O7—C7—N4	123.37 (13)
H3A—C3—H3B	107.7	O7—C7—C8	122.46 (13)
N4—C4—C5	109.61 (10)	N2—C7—C8	114.16 (12)
N4—C4—C3	109.56 (10)	C9—C8—C7	120.92 (13)
C5—C4—C3	110.04 (11)	C9—C8—H8	119.5
N4—C4—H4	109.2	C7—C8—H8	119.5
C5—C4—H4	109.2	C8—C9—H9A	120.0
C3—C4—H4	109.2	C8—C9—H9B	120.0
C4—C5—C6	112.31 (10)	H9A—C9—H9B	120.0
C4—C5—H5A	109.1	H1W—O1W—H2W	104 (2)
C6—N1—C2—C21	162.00 (11)	C2—N1—C6—C62	79.16 (14)
C6—N1—C2—C22	−81.34 (14)	C2—N1—C6—C5	−44.94 (15)
C6—N1—C2—C3	43.11 (15)	C4—C5—C6—N1	50.50 (15)
N1—C2—C3—C4	−47.21 (15)	C4—C5—C6—C61	167.44 (11)
C21—C2—C3—C4	−164.28 (11)	C4—C5—C6—C62	−73.79 (13)
C22—C2—C3—C4	77.16 (13)	C5—C4—N4—C7	−150.00 (12)
C2—C3—C4—N4	175.41 (10)	C3—C4—N4—C7	89.16 (14)
C2—C3—C4—C5	54.84 (14)	C4—N4—C7—O7	7.1 (2)
N4—C4—C5—C6	−176.68 (10)	C4—N4—C7—C8	−171.86 (11)
C3—C4—C5—C6	−56.13 (14)	O7—C7—C8—C9	−16.3 (2)
C2—N1—C6—C61	−164.04 (11)	N4—C7—C8—C9	162.73 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4N···O1W	0.84 (2)	2.07 (2)	2.9052 (16)	176.1 (18)
O1W—H2W···N1^i	0.93 (2)	1.98 (2)	2.9081 (16)	176.9 (19)
O1W—H1W···O7^ii	0.85 (3)	2.02 (3)	2.8617 (15)	168 (2)
C21—H21C···O7^iii	0.98	2.48	3.4041 (17)	157

Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) x, −y+1/2, z−1/2; (iii) −x+1, −y+1, −z+1.