Ethylene tri- and tetramerization: a steric parameter selectivity switch from X-ray crystallography and computational analysis.

A steric parameter (θN-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 θN-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.

Tricarbonylbis-(triphenyl-phosphane-κP)iridium(I) hexa-fluoridophosphate methanol monosolvate.

In the title compound, [Ir(C(18)H(15)P)(2)(CO)(3)]PF(6)·CH(3)OH, the Ir(I) atom is coordinated by two triphenyl-phosphine ligands in axial sites and three carbonyl ligands in the equatorial plane of a fairly regular trigonal bipyramid: the equatorial C-Ir-C angles range from 115.45 (9) to 126.42 (10)°. The small deviations from the ideal tetra-hedral geometry around the P atoms are illustrated by C-P-C angles ranging from 104.08 (9) to 106.46 (9)°. In the crystal, the mol-ecules are linked by weak C-H⋯F, C-H⋯O and C-H⋯π inter-actions.

Bis[N,N-bis-(diphenyl-phosphan-yl)cyclo-penta-namine-κ²P,P']platinum(II) bis-(trifluoro-methane-sulfonate).

The title compound, [Pt(C29H29NP2)2](CF3SO3)2, consists of a Pt(II) atom, situated on an inversion centre, coordinated by two diphosphinoamine bidentate ligands and charge-balanced by two trifluoro-methane-sulfonate anions. The Pt(II) atom has a distorted square-planar geometry defined by the four P atoms. The distortion is illustrated by the P-Pt-P bite angle of 70.31 (4)°. The geometry around the N atom deviates from a trigonal-planar geometry, evidenced by the P-N-P bite angle of 102.3 (2) °. The N atom is displaced by 0.114 (4) Šfrom the C/P/P plane. In order to coordinate, the orientation of the phenyl rings alters from a C(s) conformation to a C(2v) conformation. The cyclo-pentane ring is slightly twisted: the puckering parameters are q(2) = 0.420 (5) Šand ϕ = 26.5 (8) °. The trifluoro-methane-sulfonate anion displays a 0.511 (11):0.489 (11) positional disorder. Weak inter- and intra-molecular C-H⋯O hydrogen bonds influence the crystal packing.

N,N-Bis(diphenyl-phosphan-yl)cyclo-butanamine.

In the title compound, C(28)H(27)NP(2), the N atom adopts an almost planar geometry with the two P atoms and the C atom attached to it, with a distance of 0.066 (2) Šbetween the N atom and the C/P/P plane. The distorted trigonal-pyramidal geometry of the N atom is further illustrated by bond angles ranging between 115.22 (11) and 123.53 (8)°. Bond angles varying from 99.99 (9) to 108.07 (9) ° are indicative of the distorted pyramidal environment around the P atoms. An intra-molecular C-H⋯P hydrogen bond occurs. In the crystal, inter-molecular C-H⋯π inter-actions link the mol-ecules into a supra-molecular network.

Bis[N,N-bis-(diphenyl-phosphan-yl)pentyl-amine-κP,P']platinum(II) bis-(hexa-fluoridophosphate) dichloro-methane disolvate.

The Pt(II) atom in the title compound, [Pt(C(29)H(31)NP(2))(2)](PF(6))(2)·2CH(2)Cl(2), is coordinated by four P atoms from two bis-(di-phenyl-phosphan-yl)pentyl-amine ligands with an average Pt-P distance of 2.300 (1) Å. The coordination around the Pt(II) atom shows a highly distorted square-planar geometry, as evidenced by the P-Pt-P bite angles of 70.45 (3) and 70.64 (3)°. The asymmetric unit contains two hexa-fluoridophosphate ions, the metal complex and two dichloro-methane solvent mol-ecules. One of the chloride atoms of one of the dichloro-methane mol-ecules is disordered over two sites in a 0.515 (3):0.485 (3) ratio. C-H⋯F hydrogen bonds stabilize the crystal packing.

Bis[N,N-bis-(diphenyl-phosphan-yl)cyclo-hexyl-amine-κP,P']platinum(II) bis-(hexa-fluorido-phosphate) dichloro-methane disolvate.

In the title compound, [Pt(C(30)H(31)NP(2))(2)](PF(6))(2)·2CH(2)Cl(2), the four-coordinated Pt(II) atom, situated on an inversion centre, exhibits a highly distorted square-planar geometry illustrated by the P-Pt-P bite angle of 70.76 (3)°. The cyclo-hexyl ring and one of the phenyl rings display 0.630 (7):0.37 (7) and 0.60 (2):0.40 (2) positional disorder, respectively. The dichloro-methane solvent mol-ecule displays 0.526 (4):0.474 (4) positional disorder. C-H⋯F hydrogen bonds stabilize the crystal packing.

N,N-Bis(diphenyl-phosphanyl)cyclo-propyl-amine.

In the title compound, C(27)H(25)NP(2), the diphenyl-phosphino groups are staggered relative to the PNP backbone. The dihedral angles between the phenyl rings bonded to each P atom are 51.74 (5) and 68.23 (4)°. The coordination around the N atom deviates from trigonal-pyrimidal geometry towards an almost planar arrangement between the N atom and the adjacent P and C atoms; the distance between the N atom and the plane formed by the adjacent C/P/P atoms is 0.098 (2) Å.

N,N-Bis(diphenyl-phosphan-yl)cyclo--penta-namine.

The coordination around the N atom in the title compound, C(29)H(29)NP(2), shows an almost planar geometry, defined by the attached P and C atoms, in order to accomodate the steric bulk of the phenyl rings. The distortion of the trigonal-pyramidal geometry of the N atom is illustrated by the bond angles ranging between 115.22 (12) and 121.76 (9)°. The P atoms present a pyramidal environment with bond angles ranging from 100.62 (9) to 104.71 (8)°. One of the C atoms in the cyclo-pentyl ring displays a 0.822 (4):0.178 (4) positional disorder. Within the crystal structure, intra-molecular C-H⋯P hydrogen bonds together with inter- and intra-molecular C-H⋯π inter-actions link the mol-ecules into a supra-molecular two-dimensional network.