Selective Reductions of N,N-Bis{chloro(aryl)-phosphino}-amines Yielding Three-, Five-, Six-, and Eight-Membered Cyclic Azaphosphanes.

To date, a plethora of λ3 -P nitrogen-containing compounds is known. A large number of them are used as ligands in coordination chemistry and homogeneous catalysis. PN-containing compounds tend to build up cyclic moieties, which have received less attention in regard to their application as ligands in transition metal chemistry. Hence, different dehalogenation reactions of N,N-bis{chloro(aryl)-phosphino}-amines have been developed to synthesize different P-N-P containing cyclic compounds. Their coordination behavior to group VI transition metal carbonyls was explored.

2,4-Bis(diphenyl-phosphan-yl)-1,1,2,3,3,4-hexa-phenyl-1,3-diphospha-2,4-dibora-cyclo-butane tetra-hydro-furan sesqui-solvate.

In the title compound, C(60)H(50)B(2)P(4)·1.5C(4)H(8)O, the diphospha-diborane mol-ecule lies on an inversion centre, whereas the disordered tetra-hydro-furan solvent mol-ecule is in a general position with a partial occupancy of 0.75. The diphosphadiborane mol-ecule consists of an ideal planar four-membered B(2)P(2) ring with an additional phenyl and a -PPh(2) group attached to each B atom.

Tetra-carbon-yl[bis-(diphenyl-phosphan-yl)tetra-methyl-disiloxane-κP,P']chromium(0).

The title compound, [Cr(C(28)H(32)OP(2)Si(2))(CO)(4)], was obtained by the ligand-exchange reaction of Cr(CO)(6) with (Ph(2)PSiMe(2))(2)O in refluxing toluene. The CrC(4)P(2) coordination geometry is distorted octa-hedral, with a P-Cr-P bite angle of 99.22 (4)°.

(Isopropyl-amino)(meth-yl)diphenyl-phospho-nium iodide.

The title compound, C(16)H(21)NP(+)·I(-), was obtained by the reaction of Ph(2)PN((i)Pr)P(Ph)N((i)Pr)H with MeI involving cleavage of one of the P-N bonds in diethyl ether. The two phenyl rings form a dihedral angle of 82.98 (5)°. A weak donor-acceptor N-H⋯I inter-action is observed.

N,P,P-Triisopropyl-phosphinic amide.

The title compound, C(9)H(22)NOP, was obtained by slow diffusion of oxygen into a toluene solution of (i)Pr(2)PNH(i)Pr. In the crystal, an inter-molecular N-H⋯O hydrogen bond occurs.

Activation and deactivation by temperature: behavior of Ph2PN(iPr)P(Ph)N(iPr)H in the presence of alkylaluminum compounds relevant to catalytic selective ethene trimerization.

Coordination, deprotonation, rearrangement, and cleavage of Ph(2)PN(iPr)P(Ph)N(iPr)H (1) by trialkylaluminum compounds R(3)Al (R=Me, Et) are reported that are relevant to the selective ethene trimerization system consisting of the ligand 1, CrCl(3)(THF)(3) and Et(3)Al that produces 1-hexene in more than 90% yield and highest purity. With increasing temperature and residence time first the formation of an adduct [Ph(2)PN(iPr)P(Ph)N(iPr)H][AlR(3)] (2), second the aluminum amide [Ph(2)PN(iPr)P(Ph)(AlR(3))N(iPr)][AlR(2)] (3) and third its rearrangement to the cyclic compound [N(iPr)P(Ph)P(Ph(2))N(iPr)][AlR(2)] (4) were observed. The cleavage of 3 by an excess of R(3)Al into an amidophosphane and an iminophosphane could be the reason for its rearrangement to complex 4, as well as to the cyclic dimer [R(2)AlN(iPr)P(Ph)(2)](2) (5). The chemistry of ligand 1 in the presence of alkylaluminum compounds gives hints on possible activation and deactivation mechanisms of 1 in trimerization catalysis.

Coordination chemistry of new selective ethylene trimerisation ligand Ph2PN(iPr)P(Ph)NH(R) (R = iPr, Et) and tests in catalysis.

The synthesis of [Ph(2)PN((i)Pr)P(Ph)NH(R)] (R = (i)Pr, Et) (1, 2) is described and the structure of 2 has been determined by single-crystal X-ray analysis. Compound 1 readily reacts with chromium(0), nickel(0), nickel(II), palladium(II), platinum(II) and iron(II) complexes to give four-membered rings (3-10) via P,P' coordination. The molecular structures of [Cr(CO)(4){Ph(2)PN((i)Pr)P(Ph)NH(R)-P,P'}] (R = (i)Pr, Et) (3, 4), [Cr(CO)(3)(NCCH(3)){Ph(2)PN((i)Pr)P(Ph)NH((i)Pr)-P,P'}] (5), [Ni{Ph(2)PN((i)Pr)P(Ph)NH((i)Pr)-P,P'}(2)] (6), cis-[MX(2){Ph(2)PN((i)Pr)P(Ph)NH((i)Pr)-P,P'}] (M = Ni, Pd, Pt; X = Cl or Br) (7, 8, 9) and trans-[Fe(NCCH(3))(2){Ph(2)PN((i)Pr)P(Ph)NH((i)Pr)-P,P'}(2)](BF(4))(2) (10) have been determined by X-ray diffraction. In the solid state, these complexes show tight phosphine bite angles in the range 67.89(2) degrees to 74.97(4) degrees and the central nitrogen atom adopts an almost planar (sp(2)) geometry. Complexes 3, 5, 6, 7 and 10 are tested for their catalytic activity in ethylene oligomerisation. Additionally, complex 10 is tested in hydrogenation of olefins.

An alternative mechanistic concept for homogeneous selective ethylene oligomerization of chromium-based catalysts: binuclear metallacycles as a reason for 1-octene selectivity?

An alternative concept for the selective catalytic formation of 1-octene from ethylene via dimeric catalytic centers is proposed. The selectivity of the tetramerization systems depends on the capability of ligands to form binuclear complexes that subsequently build up and couple two separate metallacyclopentanes to form 1-octene selectively. Comparison of existing catalytic processes, the ability of the bis(diarylphosphino)amine (PNP) ligand to bridge two metal centers, and the experimental background support the proposed binuclear mechanism for ethylene tetramerization.

Influence of process parameters on the reaction kinetics of the chromium-catalyzed trimerization of ethylene.

In this paper we report the results of an extensive experimental kinetic study carried out on the novel ethylene trimerization catalyst system, comprising the chromium source [CrCl(3)(thf)(3)] (thf=tetrahydrofuran), a Ph(2)P-N(iPr)-P(Ph)-N(iPr)H (PNPNH) ligand (Ph=phenyl, iPr=isopropyl), and triethylaluminum (AlEt(3)) as activator. It could be shown that the initial activity shows a first-order dependency on the ethylene concentration. Also, a first-order dependency was found for the catalyst concentration. The initial activity follows a typical Arrhenius behavior with an experimentally determined activation energy of 52.6 kJ mol(-1). At elevated temperatures (ca. 80 degrees C), a significant deactivation was observed, which can be tentatively traced back to a ligand rearrangement in the presence of AlEt(3). After a fast initial phase, a pronounced 'kink' in the ethylene-uptake curve is observed, followed by a slow, almost linear, further increase of the total ethylene consumption. The catalyst composition, in particular the ligand/chromium and the cocatalyst/chromium molar ratio, has a strong impact on the catalytic performance of the trimerization of ethylene.

Bis[µ-N,N'-bis(2,6-diisopropylphenyl)ethene-1,2-diamido]-1,4(η);1:2κN:N;3:4κN:N-bis(diethyl ether)-1κO,4κO-di-µ-hydrido-2:3κH:H-2,3-dichromium(II)-1,4-dilithium(I) pentane hemisolvate.

The title compound, [Cr(2)Li(2)(C(26)H(36)N(2))(2)(µ-H)(2)(C(4)H(10)O)(2)]·0.5C(5)H(12), is a binuclear chromium complex bridged by two hydrogen atoms. Each chromium atom is coordinated in a distorted square-planar geometry by one chelating bis-(2,6-diisopropyl-phen-yl)ethene-1,2-diamido ligand via its two N atoms. Additionally, two diametrically opposed lithium ether adducts coordinate in an η(4) mode on the backbone of the ligands. There is a crystallographic inversion center in the middle of the Cr(2)H(2) ring. One of the isopropyl groups is disordered over two positions in a 0.567 (7):0.433 (7) ratio. Disorder is also observed in the pentane hemisolvate molecule.

[Bis(diphenyl-phosphan-yl)dimethyl-silane-κP,P']tetra-carbonyl-chromium(0).

The title compound, [Cr(C(26)H(26)P(2)Si)(CO)(4)], was obtained by the reaction of Ph(2)PSiMe(2)PPh(2) with Cr(CO)(6) in refluxing toluene by ligand exchange. The CrC(4)P(2) coordination geometry at the Cr atom is distorted octa-hedral, with a P-Cr-P bite angle of 80.27 (1)°.

[2,2-Bis(diphenyl-phosphan-yl)propane-κP,P']tetra-carbonyl-chromium(0) dichloro-methane monosolvate.

The title compound, [Cr(C(27)H(26)P(2))(CO)(4)]·CH(2)Cl(2), was obtained by the reaction of Ph(2)PCMe(2)PPh(2) with Cr(CO)(6) in refluxing toluene by substitution of two carbonyl ligands. The CrC(4)P(2) coordination geometry at the Cr atom is distorted octa-hedral, with a P-Cr-P bite angle of 70.27 (2)°.

Diacetonitrile[N,N'-bis(2,6-diisopropyl-phenyl)ethane-1,2-diimine]dichloridochromium(II) acetonitrile solvate.

The title compound, [CrCl(2)(CH(3)CN)(2)(C(26)H(36)N(2))]·CH(3)CN, was synthesized by the reaction of CrCl(2)(THF)(2) with N,N'-bis-(2,6-diisopropyl-phen-yl)ethane-1,2-diimine in dichloro-methane/acetonitrile. The chromium center is coordinated by two N atoms of the chelating diimine ligand, two chloride ions in a trans configuration with respect to each other, and by two N atoms of two acetonitrile mol-ecules in a distorted octa-hedral geometry.

Bis[N,N'-bis-(2,6-diisopropyl-phen-yl)ethane-1,2-diimine]-1κN,N';2κN,N'-tri-µ-trichlorido-1:2κCl:Cl-chlorido-1κCl-tetra-hydro-furan-2κO-dichromium(II) dichloro-methane 4.5-solvate.

In the mol-ecular structure of the title compound, [Cr(2)Cl(4)(C(26)H(36)N(2))(2)(C(4)H(8)O)]·4.5CH(2)Cl(2), the two Cr(II) centers are bridged by three Cl atoms, forming a dinuclear complex. Each Cr(II) center is coordinated by one chelating bis-(2,6-diisopropyl-phen-yl)ethane-1,2-diimine ligand via both N atoms. An additional chloride ion binds to one chromium center, whereas an additional tetra-hydro-furan mol-ecule coordinates to the second Cr(II) center. The coordination geometry at each Cr(II) center can be best described as distorted octa-hedral.

1,1,2,2-Tetra-phenyl-1λ-diphosphane 1-sulfide.

In the title mol-ecule, C(24)H(20)P(2)S, the P-P bond length is 2.2263 (5) Å. The two phenyl rings attached to the three- and five-coordinated P atoms, respectively, form dihedral angles of 56.22 (5) and 71.74 (5)°.

P-[N-(Diphenyl-phospho-rothio-yl)iso-propyl-amino]-N-isopropyl-P-phenyl-thio-phosphinic amide.

The title compound, C(24)H(30)N(2)P(2)S(2), was obtained by the reaction of Ph(2)PN(iPr)P(Ph)N(iPr)H with elemental sulfur in tetra-hydro-furan. In the solid state, intra-molecular N-H⋯S hydrogen bonding influences the mol-ecular conformation; a P-N-P-N torsion angle of 2.28 (9)° is observed. The two phenyl rings attached to one P atom form a dihedral angle of 74.02 (4)°.

2-Phosphinophenolate complexes: formation and crystal structure of a novel trinuclear mu-O nickel(II)-tris(P(intersection)O-chelate).

A novel linear trinuclear mu-O-bridging 2-phosphinophenolate nickel(II) complex with fac-tris(P(intersection)O- chelates) in the terminal positions and the three oxygen atoms each facing the central nickel(II) cation was synthesized and structurally characterized by X-ray crystallography. To the best of our knowledge, this is the first example of an octahedral Ni(II) tris(P(intersection)O- chelate).

Novel alpha-functionally substituted amino acids: diphenylphosphinoglycines.

The three-component one-pot reaction of glyoxalic acid hydrate with P-H and N-H compounds allows a convenient access to phosphinoglycines. The molecular structure of , determined by X-ray crystallography, some reactions and an alternative formation of phosphinoglycolates are reported.

2-phosphanylphenolate nickel catalysts for the polymerization of ethylene.

The previously unknown methallylnickel 2-diorganophosphanylphenolates (R=Ph, cHex) were synthesized and found to catalyze the polymerization of ethylene. To explore the potential for ligand-tuning, a variety of P-alkyl- and P-phenyl-2-phosphanylphenols was synthesized and allowed to react with [Ni(cod)(2)] (cod=1,5-cyclooctadiene) or with NiBr(2).DME and NaH. The complexes formed in situ with [Ni(cod)(2)] are generally active as ethylene polymerization catalysts with all the ligands tested, whereas the latter systems are inactive when 2-dialkylphosphanylphenols are applied. M(w) values, ranging from about 1000 to about 100000 g mol(-1), increase for various R(2)P groups in the order R=Ph