N,N-Bis(diphenyl­phosphino)-1,2-dimethyl­propyl­amine

Nicoline Cloete; Hendrik G Visser; Andreas Roodt; Jontho T Dixon; Kevin Blann

doi:10.1107/S1600536808001839

. 2008 Jan 23;64(Pt 2):o480. doi: 10.1107/S1600536808001839

N,N-Bis(diphenylphosphino)-1,2-dimethylpropylamine

Nicoline Cloete ^a,^*, Hendrik G Visser ^a, Andreas Roodt ^a, Jontho T Dixon ^b, Kevin Blann ^b

PMCID: PMC2960458 PMID: 21201505

Abstract

The diphenylphosphine groups in the title compound, C₂₉H₃₁NP₂, are staggered relative to the PNP backbone. The N atom adopts an almost planar geometry with the two P atoms and the C atom attached to it, in order to accommodate the steric bulk of the phenyl groups and the alkyl group. Three C atoms of the 1,2-dimethylpropylamine group are disordered over two positions in a 9:1 ratio. The molecules pack diagonally in the unit cell across the ac plane in a head-to-tail fashion.

Related literature

For similar structures, see: Keat et al. (1981 ▶); Cotton et al. (1996 ▶); Fei et al. (2003 ▶). For ethylene tetramerization, see: Bollmann et al. (2004 ▶).

Experimental

Crystal data

C₂₉H₃₁NP₂
M _r = 455.49
Triclinic,
a = 9.242 (5) Å
b = 10.454 (5) Å
c = 12.899 (5) Å
α = 91.031 (5)°
β = 98.188 (5)°
γ = 102.775 (5)°
V = 1201.4 (10) Å³
Z = 2
Mo Kα radiation
μ = 0.20 mm⁻¹
T = 101 (2) K
0.47 × 0.29 × 0.14 mm

Data collection

Bruker Kappa APEXII diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.912, T _max = 0.974
24124 measured reflections
5947 independent reflections
5313 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.107
S = 1.09
5947 reflections
299 parameters
H-atom parameters constrained
Δρ_max = 0.56 e Å⁻³
Δρ_min = −0.52 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-Plus (Bruker, 2004 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808001839/pv2057sup1.cif

e-64-0o480-sup1.cif^{(21.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808001839/pv2057Isup2.hkl

e-64-0o480-Isup2.hkl^{(285.2KB, hkl)}

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

Acknowledgments

Financial assistance from the South African National Research Foundation (NRF), the Research Fund of the University of the Free State and Sasol is gratefully acknowledged. Part of this material is based on work supported by the South African National Research Foundation (GUN 2038915). Opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NRF.

supplementary crystallographic information

Comment

Diphosphinoamine (PNP) ligands with various substituents on both the P and N atoms have proven to be very effective in ethylene tetramerization catalyst systems and have been shown to produce 1-octene in good selectivity (Bollmann et al., 2004). It seems that the substituents on the N atom profoundly affected the catalyst productivity. This paper forms part of a structural and kinetic investigation into the mechanism of the catalytic cycle.

The crystals of the title compound, (I), crystallize in the triclinic space group. All bond distances and angles in (I) (Figure 1a) are considered to be normal and fall within the range reported for similar complexes (Keat et al., 1981; Cotton et al., 1996; Fei et al., 2003). A slight disorder of 12% is observed in the 1,2-dimethylpropylamine substituent (Figure 1 b). The distance of N1 from the P1—P2—C1 plane was calculated as 0.216 (2) Å. The geometry around the phosphorous ligands is distorted from tetrahedral geometry with C—P—C angles being the most distorted (varying from 99.56 (7)° to 99.78 (7)°). The P1—N1—P2 angle is 117.83 (7)°.

Experimental

1,2-Dimethylpropylamine (0.01 mole, 0.811 g) was dissolved in dichloromethane (30 ml) and placed in an ice bath. Triethylamine (0.03 mol, 4.22 ml) was added to the solution while it was being stirred. Chlorodiphenylphosphine (0.02 mol, 3.62 ml) was slowly added to the reaction mixture. The ice bath was removed after 30 minutes and the reaction mixture was allowed to stir at room temperature for a further 12 hrs.

The dichloromethane was removed under reduced pressure. A mixture of hexane (20 ml) and toluene (2 ml) was added to the remaining white powder and was passed through a column containing neutral activated alumina (35 g). The solvent of the eluent was removed under reduced pressure and the white precipitate was collected. The product was recrystallized from methanol, single colourless crystals were obtained (yield 2.551 g, 56.1%) the next day which were suitable for X-ray crystallography.