The Phospha–Michael addition product {(t-BuNH)P(μ-N-t-Bu)2P(=N-t-Bu)—C(=CH2)CH(p-CH3O—C6H4)-P(O)[(OCH2C(CH3)2CH2O)]}

G Gangadhararao; Srinivas Venu

doi:10.1107/S1600536811014127

. 2011 Apr 29;67(Pt 5):o1212–o1213. doi: 10.1107/S1600536811014127

The Phospha–Michael addition product {(t-BuNH)P(μ-N-t-Bu)₂P(=N-t-Bu)—C(=CH₂)CH(p-CH₃O—C₆H₄)-P(O)[(OCH₂C(CH₃)₂CH₂O)]}

G Gangadhararao ^a, Srinivas Venu ^a,^*

PMCID: PMC3089203 PMID: 21754511

Abstract

The title compound, 2-{2-[1,3-di-tert-butyl-4-(tert-butylamino)-2-(tert-butylimino)-1,3,2λ⁵,4-diazadiphosphetidin-2-yl]-1-(4-methoxyphenyl)prop-2-en-1-yl}-5,5-dimethyl-1,3,2λ⁵-dioxaphosphinan-2-one, C₃₁H₅₇N₄O₄P₃, was synthesized from the Phospha–Michael addition reaction of cyclodiphosphazane [(t-BuNH)P(μ-Nt-Bu)]₂ and allenylphosphonate [(OCH₂C(CH₃)₂CH₂O)P(O)C(p-CH₃O—C₆H₄)=C=CH₂]. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds link the molecules. The structure exhibits pseudosymmetry but attempts to solve it in a higher (monoclinic) space group were unsuccessful.

Related literature

For background to cyclodiphosph(III)azanes, see: Rama Suresh et al. (2009 ▶); Balakrishna (2010 ▶); Balakrishna et al. (2010 ▶). For their use as probes for organic reactions (the P atom reacts readily with activated alkenes/alkynes or azodicarboxylates), see: Satish Kumar et al. (2004 ▶); Praveen Kumar et al. (2004 ▶); Balaraman & Kumara Swamy (2004 ▶); Bhuvan Kumar & Kumara Swamy (2007 ▶, 2008 ▶); Kumara Swamy et al. (2010 ▶, 2011 ▶). It has been shown recently that their reactions with allenes generates a chiral carbon center and in some cases spontaneous resolution by crystallization can be effected (Bhuvan Kumar & Kumara Swamy (2008 ▶). For related structures, see: Chakravarty et al. (2005 ▶); Kumara Swamy et al. (2010 ▶, 2011 ▶).

Experimental

Crystal data

C₃₁H₅₇N₄O₄P₃
M _r = 642.72
Triclinic,
a = 13.8603 (9) Å
b = 15.7746 (10) Å
c = 16.2606 (11) Å
α = 88.004 (1)°
β = 84.949 (1)°
γ = 87.600 (1)°
V = 3536.6 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.21 mm⁻¹
T = 100 K
0.22 × 0.18 × 0.14 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.956, T _max = 0.972
27730 measured reflections
12397 independent reflections
9894 reflections with I > 2σ(I)
R _int = 0.033

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.128
S = 1.01
12397 reflections
795 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.54 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Data collection: SMART (Bruker, 2002 ▶); cell refinement: SAINT (Bruker, 2002 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811014127/zj2002sup1.cif

e-67-o1212-sup1.cif^{(44.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811014127/zj2002Isup2.hkl

e-67-o1212-Isup2.hkl^{(606KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N8—H8D⋯O1ⁱ	0.82 (2)	2.61 (3)	3.394 (2)	160 (2)
N4—H4D⋯O5ⁱⁱ	0.84 (3)	2.58 (3)	3.378 (2)	158 (2)
C26—H26B⋯O5ⁱⁱⁱ	0.96	2.49	3.325 (3)	145

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The National Single Crystal Diffractometer Facility at the School of Chemistry, University of Hyderabad, funded by DST (New Delhi), and the UPE and the CAS programs of the UGC for other equipment are gratefully acknowledged. We thank Professor K. C. Kumara Swamy and Dr Srinivasulu Aitipamula for useful discussions. GG and VS thank the CSIR for fellowships.

supplementary crystallographic information

Comment

Cyclodiphosph(III)azanes are good phosphorus based ligands (Rama Suresh et al., 2009; Balakrishna et al., 2010). They can also act as probes for organic reactions since the P(III) centre reacts readily with activated alkenes/ alkynes or azodicarboxylates (Satish Kumar et al., 2004; Praveen Kumar et al., 2004; Balaraman et al., 2004; Bhuvan Kumar et al., 2007; 2008; Kumara Swamy et al., 2010; 2011). It has been shown recently that their reactions with allenes generates a chiral carbon center and in some cases spontaneous resolution by crystallization can be effected (Bhuvan Kumar et al., 2008). To probe this aspect further we reacted cyclodiphosph(III)azane [(t-BuNH)P(µ-N-t-Bu)]₂ (1a) with allene (OCH₂CMe₂CH₂O)P(O)C(C₆H₄-p-OCH₃)═C═CH₂ (1b). The reaction afforded compound 1 (Scheme 1) as essentially a single product. The X-ray structure of compound 1 [Figure 1] clearly show the phosphinimine moiety at P(2) and P(5) with P—N distances of 1.546 (4) and 1.546 (1) that are slightly longer than the structures reported earlier (Chakravarty et al., 2005; Kumara Swamy et al., 2010). However, these are still in the range expected for P=N distances; the P—N single bond distances in the cyclophosphazane ring also lie in the same range of the previously reported structures (Kumara Swamy et al., 2011). However, the P—N(ring) distances involving P(III) phosphorus atoms are comparatively longer than that for P(V) phosphorus. The P–C distances are also in line with the structures as written. The P—N—P and N—P—N bond angles are also in the expected range.The crystal packing in compound 1 is mostly governed by classical hydrogen bonds. The two molecules in the asymmetric unit are extended in a one-dimensional fashion through N—H···O interactions [N(4)—H(4D)···O5 and N(8)—H(8D)···O(1)] (Figure 2). But only the first molecule was also having C—H···O(=P) [C26—H(26B)···O(5)] interactions by OCH₃ hydrogen and with the phosphoryl oxygen (P═O) of the second molecule. The crystal structure is showing an alert due to the psuedo symmetry. We have investigated the possibility of solving in higher symmetry space group and also the presence of pseudo-centre of symmetry. All our attempts to solve the structure in a higher symmetry (in Monoclinic) space group were not successful. Therefore, we strongly believe that there is only a pseudo-symmetry.

Experimental

Comopound 1: This compound (1) was obtained by the reaction of cyclodiphosphazane 1a (0.561 g, 1.61 mmol) and allenylphosphonate 1b (0 474 g, 1.61 mmol) in dry toluene (8 ml) for 20 h. The solution (toluene) was concentrated in vacuo (to ca 3 ml) and cooled for 1 day at -4°C to obtain the colorless crystals of product. Yield: 0.956 g (92%). mp: 150–154°C. IR (KBr, cm^-1): 3337, 2967, 2897, 1615, 1584, 1510, 1464, 1364, 1281, 1209, 1063, 1028, 885. ¹H NMR (400 MHz, CDCl₃): δ 0.83, 1.08, 1.18, 1.29 and 1.37 (5 s, 42H, C(CH₃)₂+C(CH₃)₃), 2.69 (d, ²J(P—H) = 7.6 Hz, 1H, NH), 3.78 (s, 3H, Ar—OCH₃) 3.82–4.36 (m, 4H, OCH₂), 5.76 (d, ³J(P—H) = 28.8 Hz, 1H, =CH_AH_Bcis to P), 6.00 (dd, ³J(P—H) = 15.2 Hz, ²J(P—H) = 18.0 Hz, 1H, P(O)CH), 6.76 (d, ³J(P—H) = 52.4 Hz, 1H, =CH_AH_Btrans to P), 6.81 (d, ³J(H—H) = 8.4 Hz, 2H, Ar-H), 7.47 (d, ³J(H—H) = 8.0 Hz, 2H, Ar-H). ¹³C NMR (100 MHz, CDCl₃): δ 20.81 and 21.85 (2 s, C(CH₃)₂), 31.10 (d, ³J(P—C) = 23.4 Hz, C(CH₃)₃), 32.31 (d, ³J(P—C) = 6.0 Hz, C(CH₃)₃), 32.78 (d, ³J(P—C) = 9.2 Hz, C(CH₃)₃), 34.39 (d, ³J(P—C) = 11.2 Hz, C(CH₃)₃), 40.72 (d, ¹J(P—C) = 125.4 Hz, P(O)C(Ar)), 51.31 (d, ²J(P—C) = 14.5 Hz, C(CH₃)₃), 52.25 (d, ²J(P—C) = 8.8 Hz, C(CH₃)₃), 52.51 (d, ²J(P—C) = 7.7 Hz, C(CH₃)₃), 55.08 (Ar—OCH₃),76.38 and 76.42 (2 s, OCH₂), 113.52, 128.06, 131.05, 131.12, 158.67 (d, ²J(P—C) = 6.4 Hz, Ar-C + PC=CH₂), 143.56 (d, ¹J(P—C) = 159.0 Hz, PC=CH₂). ³¹P NMR (160 MHz, CDCl₃): δ -18.90 (dd, ³J(P—P) = 35.8 Hz, ²J(P—P) = 6.7 Hz), 20.91 (d, ³J(P—P) = 35.8 Hz), 70.99 (br d, ²J(P—P) = 6.7 Hz). LC—MS: m/z 643 [M+1]⁺. Anal. Calc. For C₃₁H₅₇N₄O₄P₃: C, 57.93; H, 8.94; N, 8.72. Found: C, 57.79; H, 8.98; N, 8.82. A suitable crystal (Shape: blocks: Size: 0.22 x 0.18 x 0.14 mm³) was mounted on a glass fibre and data was collected on BRUKER SMART diffractometer at 100 K.