A di­phenyl­boron chelate of an ethyl­enebis­hydroxyl­amine form­aldehyde adduct

1,2-Bis­[2,2-di­phenyl-4-(2-propyl)-1,3-dioxa-4-azonia-2-borata­­cyclo-4-pentyl]­ethane, C₃₄H₄₂B₂N₂O₄, crystallizes with the mol­ecules lying on crystallographic inversion centres. The five-membered COBON ring has a half-chair conformation, with about 25% double-bond character for the C-O bond.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.038
• wR factor = 0.051
• Data-to-parameter ratio = 10.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level B:



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           77.40
         From the CIF: _reflns_number_total               2975
         TEST2: Reflns within _diffrn_reflns_theta_max
         Count of symmetry unique reflns         3455
         Completeness (_total/calc)             86.11%
          Alert B: < 90% complete (theta max?)


 0 Alert Level A = Potentially serious problem

 1 Alert Level B = Potential problem

 0 Alert Level C = Please check

---

S1. Comment

From the reaction of substituted ethylenebishydroxylamines and organoboron compounds, some different types of boron complexes have been obtained and structurally established by X-ray crystallography (Amt et al., 1988, 1990a,b). In the course of these investigations, the reaction of a series of N,N'-dialkylethylenebishydroxylamines, (2) [which can be synthesized by reduction of glyoxalbisnitrones, (1)], with formaldehyde and diphenylborinic acid (anhydride) resulted in the incorporation of two molecules each of formaldehyde and diphenylborinic acid into (2) (Amt, 1990). The elemental analyses and ¹H NMR spectra of the crystalline compounds are consistent with at least three symmetrical structural alternatives, two ethylene-linked five-membered diphenylboron chelates, (3) and (4), and an eight-membered bicyclic product (5). Since spectroscopic data were not sufficient for distinction among the isomeric structures, an X-ray analysis of the N,N'-diisopropyl derivative, which gave the best single crystals in the series of homologous compounds, was carried out.

The structure analysis establishes the molecular constitution (3) (R = 2-C₃H₇), generated by an electrophilic attack of formaldehyde at the hydroxylamine N atom and subsequent (or simultaneous) chelate formation with diphenylborinic acid. Analogous COBON chelate ring systems have been found in the diphenylboron complexes of the reaction products from N,N-dimethylhydroxylamine and formaldehyde (Rettig et al., 1974) or acetone (Kliegel et al., 1984), acetone oxime and formaldehyde (Kliegel et al., 1995), and also, as part of a polycyclic ring system, from phenylboronic acid, N-hydroxypiperidine and salicyladehyde (Kliegel et al., 1990).

The molecule of (3) (Fig. 1) lies on a crystallographic inversion centre. The five-membered ring has a half-chair conformation, with C1 and O2 lying on opposite sides of the B—O1—N plane. The dihedral angles in the ring are almost identical with those in compounds with the same ring system studied previously (e.g. Rettig et al., 1974).

Bond lengths and angles are also close to those in related molecules. The C1—O2 bond in the COBON ring [1.360 (2) Å] has considerable double-bond character (about 25%) (retained from the carbonyl moiety of the formaldehyde from which it derives); this results from back donation from oxygen to carbon The calculated bond order (Paolini, 1990) is 1.24, while that estimated from a bond-length versus bond-order plot (Häfelinger, 1970) is 1.27. This double-bond character in the C1—O2 bond of (3) is slightly greater than those of the corresponding C—O bonds in the COBON rings of the other compounds reported: 1.378 Å (Rettig et al., 1974) 1.387 Å (Kliegel et al., 1984), 1.380 Å (Kliegel et al., 1995), and 1.382 Å (Kliegel et al., 1990). In spite of the partially retained carbonyl π-bond, all these compounds exhibit shorter (stronger) B—O(C) bonds and longer (weaker) B—O(N) bonds, the differences ranging from 0.03 to 0.08 Å [for (3), B–O2(C1) = 1.487 (3) Å and B—O1(N) = 1.555 (2) Å].

S2. Experimental

For the preparation of N N'-ethanediylidenebis(2-propanamine) N,N'-dioxide, (1) (R = 2-C₃H₇), N-(2-propyl)hydroxylamine (2.25 g, 30 mmol) and glyoxal (0.87 g, 15 mmol, applied as hydrate) were heated in 50 ml of ethanol under reflux conditions for 15 min. After evaporating the solution to one-third of its initial volume, the solution was cooled and yielded 1.62 g (63%) of colourless needles, m.p. 479 K (decomposition) (from ethanol). IR (KBr): 1520 cm^-1 (C═N). ¹H NMR (90 MHz, CDCl₃/TMS), δ (p.p.m.): 1.45 (d, J = 6 Hz, 4 CH₃), 4.12 (m, J = 6 Hz, 2 N—CH), 7.80 (s, 2 N═CH). Analysis calculated for C₈H₁₆N₂O₂: C 55.79, H 9.36, N 16.27%; found: C 55.89, H 9.58, N 16.26%.

For the preparation of N,N'-dihydroxy-N,N'-di(2-propyl)ethylenediamine, (2) (R = 2-C₃H₇), (1) (R = 2-C₃H₇) (3.44 g, 20 mmol) was dissolved in 100 ml of methanol/water (1:1). A solution of KBH₄ (2.16 g, 40 mmol) in 15 ml water was added. After storing for 24 h at room temperature, the solution was acidified with tartaric acid (20% aqueous solution) and subsequently neutralized with NaHCO₃. After evaporation in vacuo, the dry residue was mixed with 50 ml of water and extracted with 3 × 40 ml of chloroform. The combined organic phases were evaporated in vacuo, and the residue recrystallized from chloroform/petroleum ether. Yield: 2.39 g (68%), m.p. 354 K. IR (KBr): 3660–2560 cm^-1 (broad curtain, O—H). ¹H NMR (90 MHz, DMSO-d₆/TMS), δ (p.p.m.): 0.98 (d, J = 6 Hz, 4 CH₃), 2.72–2.76 (m, 2 N—CH, CH₂CH₂), 7.28 (s, broad, exchangeable, 2 OH). Analysis calculated for C₈H₂₀N₂O₂: C 54.51, H 11.44, N 15.89%; found: C 54.63, H 11.70,N 15.80%.

For the preparation of 1,2-bis[2,2-diphenyl-4-(2-propyl)-1,3-dioxa-4-azonia-2- boratacyclo-4-pentyl]ethane, (3) (R = 2-C₃H₇), (2) (R = 2-C₃H₇) (0.35 g, 2 mmol) and formaldehyde (0.3 ml of 40% aqueous solution, 4 mmol) were dissolved in 20 ml of ethanol at room temperature under stirring. To the clear solution. oxybis(diphenylborane) (0.69 g, 2 mmol) in 10 ml of ethanol was added and stirring continued until crystallization began. After cooling to 255 K, the crystals were collected and washed with cold ethanol and subsequently with ether. Yield: 0.88 g (79%) of colourless, analytically pure crystals, m.p. 458–459 K (decomposition). ¹H NMR (90 MHz, DMSO-d₆/TMS), δ (p.p.m.): 0.75 (d, J = 6 Hz, 2 CH₃), 1.12 (d, J = 6 Hz, 2 CH₃), 3.10–3.72 (m, 2 N—CH, CH₂CH₂), 4.61 and 5.00 (d and d, AB-system, J = 5 Hz, 2 N—CH₂—O), 6.84–7.43 (m, 20 aromatic H). Analysis calculated for C₃₄H₄₂B₂N₂O₄: C 72.62, H 7.53, N 4.98%; found: C 72.56, H 7.61, N 4.99%. The compound gave a blue colour reaction with diphenylcarbazone in methanolic solution, indicating the presence of a diphenylboron moiety (Neu, 1960; Friese & Umland, 1978). Crystals suitable for X-ray crystallography were obtained by slow crystallization from nitroethane.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1989); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1989); program(s) used to solve structure: MITHRIL (Gilmore, 1984); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

Figures

Fig. 1. A view of the molecular structure of (3) (33% probability ellipsoids).

(3)

Crystal data

C34H42B2N2O4	F(000) = 604
Mr = 564.34	Dx = 1.152 Mg m^−3
Monoclinic, P21/n	Cu Kα radiation, λ = 1.54178 Å
a = 10.5826 (9) Å	Cell parameters from 25 reflections
b = 11.6428 (6) Å	θ = 38.4–44.0°
c = 13.3394 (6) Å	µ = 0.58 mm^−1
β = 98.164 (5)°	T = 294 K
V = 1626.9 (2) Å^3	Rhomb, colourless
Z = 2	0.38 × 0.30 × 0.20 mm

Data collection

Rigaku AFC-6S diffractometer	2082 reflections with I > 3σ(I)
Radiation source: X-ray tube	Rint = 0.022
Graphite monochromator	θmax = 77.4°, θmin = 0.0°
ω–2θ scans	h = 0→13
Absorption correction: ψ scan (AFC6; Molecular Structure Corporation, 1989)	k = 0→14
Tmin = 0.80, Tmax = 0.89	l = −15→16
3295 measured reflections	3 standard reflections every 300 reflections
2975 independent reflections	intensity decay: 0.0%

Refinement

Refinement on F	0 constraints
Least-squares matrix: full	H-atom parameters not refined
R[F^2 > 2σ(F^2)] = 0.038	Weighting scheme based on measured s.u.'s 1/[σ^2(Fo) + 0.02Fo^2]
wR(F^2) = 0.051	(Δ/σ)max = 0.01
S = 1.79	Δρmax = 0.17 e Å^−3
2082 reflections	Δρmin = −0.14 e Å^−3
191 parameters	Extinction correction: Molecular Structure Corporation (1989), equ(3) Acta Cryst. (1968), A24, 213
0 restraints	Extinction coefficient: 5.74E-6 (3)

Special details

Experimental. The scan width was (1.10 + 0.20tanθ)° with an ω scan speed of 32° per minute (up to 10 scans to achieve I/σ(I) > 40). Stationary background counts were recorded at each end of the scan, and the scan time:background time ratio was 2:1. Three standard reflections remained constant in intensity for about 80% of the data collection, but decreased gradually in intensity by about 15% in the last 20% of the measurements; a linear decay correction was applied to the latter data.

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

	x	y	z	Uiso*/Ueq
O1	0.5723 (1)	0.6146 (1)	0.65669 (8)	0.0415 (6)
O2	0.7292 (1)	0.4748 (1)	0.64301 (9)	0.0434 (6)
N	0.5145 (1)	0.5047 (1)	0.6445 (1)	0.0393 (7)
C1	0.6267 (2)	0.4207 (1)	0.6726 (1)	0.0448 (9)
C2	0.4520 (2)	0.4939 (1)	0.5365 (1)	0.0494 (9)
C3	0.4188 (2)	0.4946 (2)	0.7193 (1)	0.054 (1)
C4	0.3148 (2)	0.5841 (2)	0.7001 (2)	0.072 (1)
C5	0.3668 (2)	0.3730 (2)	0.7223 (2)	0.077 (1)
C6	0.7845 (2)	0.6784 (1)	0.5981 (1)	0.0424 (9)
C7	0.7566 (2)	0.7946 (2)	0.5888 (1)	0.049 (1)
C8	0.8189 (2)	0.8673 (2)	0.5296 (2)	0.062 (1)
C9	0.9117 (2)	0.8244 (2)	0.4781 (2)	0.073 (1)
C10	0.9404 (2)	0.7087 (2)	0.4840 (2)	0.076 (1)
C11	0.8776 (2)	0.6377 (2)	0.5436 (2)	0.061 (1)
C12	0.7766 (2)	0.6204 (1)	0.7903 (1)	0.0412 (9)
C13	0.9039 (2)	0.5927 (2)	0.8241 (1)	0.056 (1)
C14	0.9601 (2)	0.6149 (2)	0.9224 (2)	0.067 (1)
C15	0.8908 (2)	0.6645 (2)	0.9903 (2)	0.067 (1)
C16	0.7656 (2)	0.6927 (2)	0.9599 (1)	0.061 (1)
C17	0.7098 (2)	0.6714 (2)	0.8604 (1)	0.049 (1)
B	0.7195 (2)	0.5972 (2)	0.6728 (1)	0.0394 (9)
H1	0.6102	0.3477	0.6365	0.053*
H2	0.6408	0.4063	0.7457	0.053*
H3	0.4113	0.4183	0.5270	0.053*
H4	0.3872	0.5540	0.5223	0.053*
H5	0.4657	0.5104	0.7866	0.063*
H6	0.2599	0.5668	0.6363	0.086*
H7	0.2637	0.5834	0.7558	0.086*
H8	0.3534	0.6601	0.6956	0.086*
H9	0.4380	0.3187	0.7347	0.092*
H10	0.3148	0.3552	0.6574	0.092*
H11	0.3141	0.3669	0.7769	0.092*
H12	0.6904	0.8264	0.6253	0.058*
H13	0.7967	0.9490	0.5247	0.075*
H14	0.9575	0.8755	0.4373	0.089*
H15	1.0051	0.6771	0.4459	0.091*
H16	0.8996	0.5558	0.5476	0.072*
H17	0.9550	0.5566	0.7769	0.067*
H18	1.0499	0.5950	0.9435	0.081*
H19	0.9306	0.6797	1.0599	0.080*
H20	0.7152	0.7278	1.0080	0.072*
H21	0.6205	0.6933	0.8396	0.058*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0390 (6)	0.0350 (6)	0.0472 (7)	−0.0016 (5)	−0.0053 (5)	−0.0056 (5)
O2	0.0427 (6)	0.0379 (6)	0.0469 (7)	0.0012 (5)	−0.0027 (5)	−0.0053 (5)
N	0.0424 (8)	0.0383 (8)	0.0344 (7)	−0.0048 (6)	−0.0035 (6)	−0.0018 (6)
C1	0.052 (1)	0.037 (1)	0.043 (1)	0.0018 (8)	−0.0041 (8)	−0.0003 (7)
C2	0.044 (1)	0.054 (1)	0.0320 (8)	−0.0088 (8)	−0.0053 (7)	−0.0034 (8)
C3	0.055 (1)	0.064 (1)	0.038 (1)	−0.005 (1)	0.0069 (8)	0.0002 (9)
C4	0.059 (1)	0.095 (2)	0.065 (1)	0.010 (1)	0.018 (1)	0.000 (1)
C5	0.083 (2)	0.081 (2)	0.071 (2)	−0.025 (1)	0.022 (1)	0.011 (1)
C6	0.041 (1)	0.045 (1)	0.0387 (9)	−0.0014 (7)	−0.0056 (7)	−0.0031 (7)
C7	0.049 (1)	0.049 (1)	0.047 (1)	0.0027 (8)	−0.0014 (8)	0.0013 (8)
C8	0.067 (1)	0.053 (1)	0.065 (1)	−0.004 (1)	0.000 (1)	0.014 (1)
C9	0.074 (2)	0.077 (2)	0.072 (2)	−0.010 (1)	0.018 (1)	0.018 (1)
C10	0.073 (1)	0.079 (2)	0.084 (2)	−0.001 (1)	0.035 (1)	0.001 (1)
C11	0.061 (1)	0.053 (1)	0.069 (1)	0.001 (1)	0.019 (1)	−0.001 (1)
C12	0.044 (1)	0.0353 (9)	0.0406 (9)	−0.0050 (7)	−0.0058 (7)	0.0015 (7)
C13	0.051 (1)	0.053 (1)	0.057 (1)	0.006 (1)	−0.0128 (9)	−0.0034 (9)
C14	0.067 (1)	0.060 (1)	0.065 (1)	0.005 (1)	−0.029 (1)	0.001 (1)
C15	0.089 (2)	0.054 (1)	0.047 (1)	−0.007 (1)	−0.023 (1)	−0.000 (1)
C16	0.077 (1)	0.059 (1)	0.042 (1)	−0.012 (1)	−0.000 (1)	−0.006 (1)
C17	0.051 (1)	0.050 (1)	0.043 (1)	−0.0068 (9)	−0.0028 (8)	−0.0044 (8)
B	0.037 (1)	0.037 (1)	0.041 (1)	0.0021 (8)	−0.0039 (8)	−0.0053 (8)

Geometric parameters (Å, º)

O1—N	1.418 (2)	C6—B	1.598 (2)
O1—B	1.555 (2)	C7—C8	1.387 (3)
O2—C1	1.360 (2)	C7—H12	0.98
O2—B	1.487 (3)	C8—C9	1.370 (4)
N—C1	1.543 (2)	C8—H13	0.98
N—C2	1.503 (2)	C9—C10	1.381 (3)
N—C3	1.524 (2)	C9—H14	0.98
C1—H1	0.98	C10—C11	1.381 (4)
C1—H2	0.98	C10—H15	0.98
C2—C2^i	1.510 (4)	C11—H16	0.98
C2—H3	0.98	C12—C13	1.396 (3)
C2—H4	0.98	C12—C17	1.384 (3)
C3—C4	1.511 (3)	C12—B	1.620 (2)
C3—C5	1.521 (3)	C13—C14	1.385 (3)
C3—H5	0.98	C13—H17	0.98
C4—H6	0.98	C14—C15	1.371 (4)
C4—H7	0.98	C14—H18	0.98
C4—H8	0.98	C15—C16	1.369 (3)
C5—H9	0.98	C15—H19	0.98
C5—H10	0.98	C16—C17	1.396 (2)
C5—H11	0.98	C16—H20	0.98
C6—C7	1.387 (3)	C17—H21	0.98
C6—C11	1.388 (3)
O2···C16^ii	3.563 (2)	C1···C16^ii	3.470 (3)
O2···C17^ii	3.592 (3)	C1···C7^ii	3.563 (2)
C1···C17^ii	3.439 (3)	C14···C14^iii	3.415 (5)
N—O1—B	107.8 (1)	C11—C6—B	121.7 (2)
C1—O2—B	106.1 (1)	C6—C7—C8	122.3 (2)
O1—N—C1	103.9 (1)	C6—C7—H12	118.8
O1—N—C2	108.0 (1)	C8—C7—H12	118.9
O1—N—C3	108.1 (1)	C7—C8—C9	119.7 (2)
C1—N—C2	113.5 (1)	C7—C8—H13	120.1
C1—N—C3	110.6 (1)	C9—C8—H13	120.2
C2—N—C3	112.2 (1)	C8—C9—C10	119.6 (2)
O2—C1—N	104.7 (1)	C8—C9—H14	120.2
O2—C1—H1	110.7	C10—C9—H14	120.1
O2—C1—H2	110.7	C9—C10—C11	119.8 (2)
N—C1—H1	110.7	C9—C10—H15	120.0
N—C1—H2	110.7	C11—C10—H15	120.2
H1—C1—H2	109.4	C6—C11—C10	122.2 (2)
N—C2—C2^i	111.4 (2)	C6—C11—H16	118.9
N—C2—H3	108.9	C10—C11—H16	118.9
N—C2—H4	109.1	C13—C12—C17	116.3 (1)
C2^i—C2—H3	108.9	C13—C12—B	118.9 (2)
C2^i—C2—H4	109.0	C17—C12—B	124.7 (2)
H3—C2—H4	109.5	C12—C13—C14	121.8 (2)
N—C3—C4	111.8 (2)	C12—C13—H17	119.1
N—C3—C5	111.4 (2)	C14—C13—H17	119.1
N—C3—H5	106.8	C13—C14—C15	120.4 (2)
C4—C3—C5	112.9 (2)	C13—C14—H18	119.8
C4—C3—H5	106.7	C15—C14—H18	119.8
C5—C3—H5	106.8	C14—C15—C16	119.4 (2)
C3—C4—H6	109.4	C14—C15—H19	120.3
C3—C4—H7	109.5	C16—C15—H19	120.3
C3—C4—H8	109.5	C15—C16—C17	120.0 (2)
H6—C4—H7	109.5	C15—C16—H20	120.0
H6—C4—H8	109.4	C17—C16—H20	120.0
H7—C4—H8	109.5	C12—C17—C16	122.1 (2)
C3—C5—H9	109.4	C12—C17—H21	119.0
C3—C5—H10	109.5	C16—C17—H21	118.9
C3—C5—H11	109.4	O1—B—O2	101.2 (1)
H9—C5—H10	109.6	O1—B—C6	110.4 (1)
H9—C5—H11	109.4	O1—B—C12	109.9 (1)
H10—C5—H11	109.5	O2—B—C6	110.4 (1)
C7—C6—C11	116.4 (2)	O2—B—C12	112.8 (1)
C7—C6—B	121.9 (2)	C6—B—C12	111.7 (1)
O1—N—C1—O2	−32.2 (1)	C2—N—O1—B	−110.9 (1)
O1—N—C2—C2^i	60.0 (2)	C2—N—C3—C4	−57.9 (2)
O1—N—C3—C4	61.1 (2)	C2—N—C3—C5	69.4 (2)
O1—N—C3—C5	−171.5 (1)	C2—C2^i—N^i—C3^i	−179.1 (1)
O1—B—O2—C1	−34.4 (1)	C3—N—O1—B	127.4 (1)
O1—B—C6—C7	49.3 (2)	C6—C7—C8—C9	−0.1 (3)
O1—B—C6—C11	−134.7 (2)	C6—C11—C10—C9	0.5 (3)
O1—B—C12—C13	170.5 (2)	C6—B—C12—C13	−66.7 (2)
O1—B—C12—C17	−12.7 (2)	C6—B—C12—C17	110.2 (2)
O2—C1—N—C2	84.8 (1)	C7—C6—C11—C10	0.6 (3)
O2—C1—N—C3	−148.0 (1)	C7—C6—B—C12	−73.4 (2)
O2—B—O1—N	13.1 (1)	C7—C8—C9—C10	1.3 (3)
O2—B—C6—C7	160.3 (1)	C8—C7—C6—C11	−0.8 (3)
O2—B—C6—C11	−23.7 (2)	C8—C7—C6—B	175.4 (2)
O2—B—C12—C13	58.4 (2)	C8—C9—C10—C11	−1.5 (3)
O2—B—C12—C17	−124.8 (2)	C10—C11—C6—B	−175.7 (2)
N—O1—B—C6	129.9 (1)	C11—C6—B—C12	102.7 (2)
N—O1—B—C12	−106.4 (1)	C12—C13—C14—C15	0.6 (3)
N—C1—O2—B	41.8 (1)	C12—C17—C16—C15	1.0 (3)
N—C2—C2^i—N^i	−180.0000	C13—C12—C17—C16	−0.9 (3)
C1—O2—B—C6	−151.2 (1)	C13—C14—C15—C16	−0.5 (4)
C1—O2—B—C12	83.0 (2)	C14—C13—C12—C17	0.1 (3)
C1—N—O1—B	9.9 (1)	C14—C13—C12—B	177.2 (2)
C1—N—C2—C2^i	−54.6 (2)	C14—C15—C16—C17	−0.3 (3)
C1—N—C3—C4	174.2 (1)	C16—C17—C12—B	−177.8 (2)
C1—N—C3—C5	−58.4 (2)

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