Effects of constraint on the catalytic properties of transition metal complexes of phosphite esters

The catalytic properties of Ni(O) and Rh(I) complexes in the isomerization, hydrocyanation and hydrogenation of olefins have been investigated as a function of the steric and electronic properties of phosphite ester ligands. Studies done on the electronic differences between acyclic, monocyclic and bicyclic phosphite esters (Part I) were used to explain the differences in catalytic properties of the complexes of the various phosphites (Parts II, III and IV);Superior catalytic activities in olefin isomerization and hydrocyanation were shown by NiL(,4) complexes of the 4,6-disubstituted phosphorinanes compared to the NiL(,4) complexes of the unsubstituted and 5,5-disubstituted phosphorinanes, acyclic phosphites, five-membered monocyclic phosphites and bicyclic phosphites. This property has been attributed to optimum steric effects in NiL(,4) complexes of the 4,6-disubstituted phosphorinanes for ligand dissociation and coordination of olefins. The observed inactivity of the NiL(,4) complexes of the bicyclic phosphites and five-membered monocyclic phosphites has been attributed to the poor basicity of such phosphites and hence, of their NiL(,4) complexes. In addition to the strong protic acids F(,3)CCOOH and Cl(,3)CCOOH, Lewis acids such as AlCl(,3), ZnCl(,2) and TiCl(,3) were found to act as cocatalysts with NiL(,4) complexes in the isomerization and hydrocyanation of olefins. The optimum excess ligand to complex ratio for maximum rate of hydrocyanation of norbornene by the NiL(,4)/ZnCl(,2) systems was found to vary with L and is higher, the higher the maximum rate of catalysis of a complex. Attempts at asymmetric isomerization, hydrocyanation and hydrogenation of olefins using NiL(,4) and Rh(COD)L(,2)PF(,6) (L = asymmetric monocyclic and bicyclic phosphites) produced moderate optical yields

(m-Phenyl­enedimethyl­ene)diammonium p-nitro­phenyl­phosphate perchlorate

The title compound, C8H14N2 2+·C12H8N2O8P−·ClO4 −, was formed by the reaction of α,α-bis-m-xylenediamine and sodium bis-p-nitro­phenyl­phosphate in the presence of Zn(ClO4)·6H2O in methanol solution. The two amine groups of the m-xylenediammonium ion are each protonated and each hydrogen-bonded to two O atoms of the phosphate anion, which acts as a 1,3-bridge. The ammonium groups are arranged matched face to face and each pair is doubly bridged by two perchlorate ions through hydrogen bonding. In addition, there are also weak C—H⋯O inter­actions. Both the N—H⋯O and C—H⋯O inter­actions are contained in a channel down the a axis. The perchlorate oxygen atoms are disordered over two positions with site occupancy factors of ca 0.7 and 0.3

Bis{2-[(2-hy­droxy-2-methyl­prop­yl)imino­meth­yl]-4-nitro­phenolato}nickel(II) dimethyl­formamide monosolvate

In the title compound, [Ni(C11H13N2O4)2]·C3H7NO, the NiII ion is octa­hedrally coordinated in an N2O4 environment by two identical Schiff base ligands. The Ni—O bond lengths range from 2.004 (2) to 2.106 (2) Å, while the Ni—N bond lengths are 2.038 (2) and 2.0465 (19) Å. The cis bond angles range from 78.64 (8) to 97.30 (8)°, with the former being due to the small bite of the amino­alcohol ligand, while the trans bond angles range from 167.86 (8) to 171.23 (8)°. One of the alcohol H atoms forms a hydrogen bond with the dimethyl­formamide (DMF) solvent mol­ecule, while the other links mol­ecules into chains along the b axis through inter­molecular O—H⋯O hydrogen bonds. There are bifurcated C—H⋯O inter­actions involving one of the nitro groups between parallel stacks of mol­ecules in the b-axis direction

(Acetonitrile)[bis­(2-pyridylmeth­yl)amine]bis­(perchlorato)copper(II)

In the title compound, [Cu(ClO4)2(C12H13N3)(C2H3N)], the CuII atom is six-coordinate in a Jahn–Teller distorted octahedral geometry, with coordination by the tridentate chelating ligand, an acetonitrile mol­ecule, and two axial perchlorate anions. The tridentate ligand bis­(2-pyridylmeth­yl)amine chelates meridionally and equatorially while an acetonitrile mol­ecule is coordinated at the fourth equatorial site. The two perchlorate anions are disordered with site occupancy factors of 0.72/0.28. The amine H is involved in intra­molecular hydrogen bonding to the perchlorate O atoms and there are extensive but weak inter­molecular C—H⋯O inter­actions

Bis[2-(benzyl­amino)pyridine-κN](2-formyl-6-methoxy­phenolato-κ2 O 1,O 6)(nitrato-κ2 O,O′)nickel(II)

In the title compound, [Ni(C8H7O3)(NO3)(C12H12N2)2], the asymmetric unit contains a NiII atom, two mol­ecules of 2-(benzyl­amino)pyridine, a mol­ecule of deprotonated o-vanillin (3-methoxy­salicylaldehydate) and a bidentate nitrate anion. The NiII center is six-coordinated by two pyridine N atoms from 2-(benzyl­amino)pyridine, two O atoms from o-vanillin and two O atoms from the nitrate anion. The crystal packing shows two hydrogen bonds from the amine N—H group to the deprotonated phenol O atom of the o-vanillin moieties, as well as weak C—H⋯O secondary inter­actions. These inter­actions link the mol­ecules into ribbons in the c direction. The steric requirement of the bidentate nitrate and its small bite angle [61.01 (3)°] cause some orientation of the two 2-(benzyl­amino)pyridine groups. As a result, this coordination environment of the NiII center is distorted octa­hedral, as the trans angles range from 158.65 (3) to 175.76 (3)° and the cis angles range from 61.01 (3) (for the bidentate nitrate O atoms) to 102.30 (4)°

Tetra-μ3-methano­lato-tetra­kis­[(2-formyl-6-meth­oxy­phenolato)methano­lnickel(II)]

The molecule of the title compound, [Ni4(CH3O)4(C8H7O3)4(CH3OH)4], has S 4 symmetry. Each of the four NiII atoms occupies every other corner of a cube, with the alternate corners occupied by μ3-methano­late bridging groups linking to three NiII atoms. Each NiII atom is in an O6 octa­hedral coordination environment formed by three O atoms from three μ3-methano­late groups, one from methanol, and two others from a bidentate 2-formyl-6-meth­oxy­phenolate ligand. The Ni—O bond distances range from 2.0020 (14) to 2.0938 (14) Å, the cis bond angles range from 81.74 (6) to 97.63°, and the trans bond angles range from 168.76 (5) to 175.22 (6)°. There are bifurcated hydrogen-bonding inter­actions between the coordinated methanol OH groups and both the phenolic and meth­oxy O atoms of an adjoining 2-formyl-6-meth­oxy­phenolate moiety. In addition, there are weak inter­molecular C—H⋯O inter­actions involving the meth­oxy O atoms

[(6-Methyl-2-pyridylmeth­yl)(2-pyridylmeth­yl)amine][(2-pyridylmeth­yl)amine]copper(II) bis­(perchlorate)

The title compound, [Cu(C6H8N2)(C13H15N3)](ClO4)2, is a mixed ligand complex with the CuII atom coordinated by (6-methyl-2-pyridylmeth­yl)(2-pyridylmeth­yl)amine, acting as a tridentate ligand, and 2-(2-amino­meth­yl)pyridine, as a bidentate ligand, leading to an N5 square-pyramidal geometry. The amine H atoms are involved in hydrogen bonding to the perchlorate O atoms and there are extensive but weak inter­molecular C—H⋯O inter­actions in the crystal structure. The perchlorate ions are each disordered over two positions, with site occupancies of 0.601 (8):0.399 (8) and 0.659 (11):0.341 (11)

Bis[2-(benzyl­amino)­pyridine-κN 1]bis­(2-formyl­phenolato-κ2 O,O′)nickel(II)

In the title complex, [Ni(C7H5O2)2(C12H12N2)2], the NiII atom lies on a center of inversion and is coordinated in an octa­hedral geometry by two 2-(benzyl­amino)­pyridine (2-BAP) and two 2-formyl­phenolate ligands with the O-atom donors in the equatorial plane and the pyridine N atoms in axial positions. There are hydrogen-bonding inter­actions between the secondary amine H atom and the phenolate O atom, as well as C—H⋯O inter­actions, which result in the dihedral angle between the aromatic phenyl ring of the 2-formyl­phenolate moiety and the pyridine ring being 80.23 (4)°. In the packing, there are both C—H⋯π inter­actions, which link the mol­ecules into chains along the b axis, and offset π–π inter­actions involving both the pyridine and phenyl rings of the 2-BAP ligands [centroid–centroid distances = 4.0100 (8) Å for the pyridine rings and 3.6601 (8) and 4.8561 (8) Å for the phenyl rings]