N,N-Bis(diphenyl­phosphino)ethyl­amine

In the title compound, C26H25NP2, the diphenyl­phosphino groups are staggered relative to the PNP backbone, even though the ethyl substituent coordinated to the N atom is not sterically bulky. The N atom adapts an almost planar geometry with two P atoms and a C atom of the allyl group attached to it in order to accommodate the steric bulk of the phenyl groups and the alkyl group. The distortion of the trigonal-pyramidal geometry of the nitro­gen is further illustrated by the bond angles which range between 114.0 (1) and 123.7 (1)°. There are no classical inter­molecular inter­actions

[N,N-Bis(diphenyl­phosphino)propyl­amine-κ2 P,P′]dichloridoplatinum(II)

The Pt(II) atom in the title compound, [PtCl2(C27H27NP2)], has a highly distorted square-planar geometry, as evidenced by the P—Pt—P bite angle [72.4 (1)°]. The strain in the complex is further illustrated by the distorted tetra­hedral angles of the P atoms, which range between 93.5 (1) and 122.2 (1)°. It is of inter­est to note that the N atom has to adopt an almost planar geometry with the two P atoms and the C atom attached to it [it is displaced by 0.093 (2) Å from the CP2 plane] in order to accommodate the steric bulk of the phenyl groups and the alkyl group of the ligand coordinated to the PtII centre. The mol­ecules pack in horizontal rows across the bc plane. C—H⋯Cl hydrogen bonds stabilize the crystal packing

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

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

Ethylene Tri- and Tetramerization: a Steric Parameter Selectivity Switch from X‑ray Crystallography and Computational Analysis

A steric parameter (θ_N‑sub) is introduced to describe the steric bulk at the nitrogen atom on a range of PNP ligands used in ethylene tri- and tetramerization. This parameter was calculated for the free ligands and different metal complexes thereof and compared to catalytic data. A specific tendency is observed for the value of θ_N‑sub and 1-hexene selectivity, and a slight increase in 1-octene selectivity is found with increased bulkiness of the substituents on the nitrogen atom