CHARLES E. KRILEY*, MAX M. MAJERICK, STEVEN NOGAN, DAVID RICHARDSON, CHRISTOPHER HALEY, SCOTT HARMAN, CHRISTOPHER HASKINS, ALEXANDRA JENSEN.

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1 Synthesis and characterization of two novel Nickel (II) complexes. Crystal Structure of [NiCl2(tdcpme)] and [Ni(NO3)2(tdcpme)], tdcpme = [1,1,1-tris((dicyclohexylphosphino)methyl)ethane, CH2C(CH22)3 CHALES E. KILEY*, AX. AJEICK, STEVEN NOGAN, DAVID ICHADSON, CHISTOHE HALEY, SCOTT HAAN, CHISTOHE HASKINS, ALEXANDA JENSEN Abstract The complexes, [NiCl2(tdcpme)] (1) and [Ni(NO3)2(tdcpme)] (2), tdcpme = [1,1,1-tris((dicyclohexylphosphino)methyl)ethane], CH2C(CH22)3, have been prepared and characterized by1h N, 31 N, microanalysis and X-ray crystallography. The salt [NiCl2].6H2O and [Ni(NO3)2].6H20 were found to react with tdcpme to form the monomeric, four coordinate, diamagnetic complexes [NiCl2(tdcpme)] and [Ni(NO3)2(tdcpme)] respectively.

2 Introduction Our group has spent the past decade exploring the reactivity of transition metal halides and poly-dentate phosphines. A particular focus of the group has been the reactivity of the bidentate phosphine bis(dicyclohexylphosphino)methane, dcpm. A study of the literature shows the versatility and reactivity of various mono, di and tri-dentate phosphines with transition metal halides.1, 2, 3 The products of which have yielded a wide variety of catalysts for hydrogenation, polymerization and for the synthesis of new chiral molecules.4 olydentate phosphines have been found to bind in a variety of fashions (Figure 1, 2). The tdppme ligand has typically been found to bind in a tridentate fashion to the metal center although there are exceptions to this, two of which are reported here. esearch performed by Fernandez et. al.5 using olybdenum, or Tungsten, with neutral or cationic gold-(i) or (III) as the transition metal center has shown many of the different bonding modes that are available to tridentate phosphines (Figure 2). While there has been some research on complexes utilizing the tris(diphenylphosphinomethyl)ethane ligand, tdppme,6 the reactivity of tris(dicyclohexylphosphinomethyl)ethane, tdcpme, has been relatively unexplored or reported in the literature. The lack of research utilizing the tdcpme ligand is most likely due to the absence of a readily available source of tdcpme. ecently a substantial quantity of tris(dicyclohexylphosphinomethyl)ethane has been prepared, using the method developed by othwell et. al.7 The reactivity and isolation of new complexes of the tris(dicyclohexylphosphinomethyl)ethane ligand is now underway.

3 Figure 1: The bonding modes of polydentate phosphine ligands to a metal Figure 2: The bonding modes of a tri-dentate phosphine ligand to a metal = Ni, Co = henyl, clohexyl = Ni, Co = henyl, clohexyl H 3 C H 3 C H 3 C H 3 C H 3 C

4 reparation of Complexes. [NiCl2(tdcpme)] (1) To 50 ml of a methanol solution of [NiCl2] 6H2O (0.35 g, 1.5 mmol) under nitrogen was added 50 ml of a toluene solution of tdcpme (1.0 g, 1.5 mmol). An immediate color change of green to orange was observed upon the addition of the tdcpme/toluene solution. The solution was stirred for thirty minutes and let to slowly evaporate to yield orange crystals of pure product (1) in high yield (0.89 g, 91%). The percentage of chlorine that was found is slightly higher than expected due to residual methylene choride that was used as a solvent. 1H N (CDCl3, 300 Hz): d (cyclohexyl). 31 N (C6D8, 300 Hz): d (free tdcpme = d ) Anal. Calcd for NiC32H54Cl22, [NiCl2(tdcpme)]: C, 62.28; H, 9.58; Cl, 8.98;, Found: C, 62.24; H, 9.81; Cl, 14.57;, [Ni(NO3)2(tdcpme)] (2) To 50 ml of a methanol solution of [Ni(NO3)2] 6H2O (0.09 g, 0.30 mmol) was added 50 ml of a toluene solution of tdcpme (0.20 g, 0.30 mmol). The solution was then stirred for thirty minutes and left to slowly evaporate to yield a red-orange solid, in high yield 1.46 g, 95%) which was then stripped to dryness. The solid was then dissolved in hot methylene chloride and allowed to slowly evaporate to yield small red-orange crystals of pure product (2). 1H N (CDCl3, 300 Hz): d (cyclohexyl). 31 N (CDCl3, 300 Hz): d Anal. Calc. for NiN2O63C41H75, [Ni(NO3)2(tdcpme)]: C, 58.37; H, 8.96; N, 3.32;, Found: C, 59.85; H, 8.87; N, 3.17;, 9.56.

5 X-ray Crystallography reliminary examination and data collection were performed with o Ka radiation on a Nonius KappaCCD equipped with a graphite crystal, incident beam monochromator. The crystallographic structure for [NiCl2(tdcpme)] (1) was solved by direct methods using SI Hydrogen atoms were included in the refinement but restrained to ride on the atom to which they are bonded. The crystallographic structure for [Ni(NO3)2(tdcpme)] (2) was solved using the structure solution program ATTY in DIDIF99.9 The remaining atoms were located in succeeding difference Fourier syntheses. Hydrogen atoms were included in the refinement but restrained to ride on the atom to which they are bonded. efinements were performed on a LINUX C using SHELX Crystallographic drawings were done using programs OTE 11 and/or LUTON.12 Lorentz and polarizaiton corrections were applied to the data. Table 1. Crystal Data and Data Collection arameters. 1 2 Formula NiCl 2 3 C 41 H 75 Ni 3 O 6 N 2 C 41 H 75 Formula weight Space Group 2 1 /n (No. 14) 2 1 /n (No. 14) a, Å (5) (2) b, Å (17) (4) c, Å (7) (3) 90 90, (3) (9), V, Å (4) (13) Z 4 4 calc, g cm Temperature, K adiation (wavelength) o K ( Å)o K ( Å) W

6 [NiCl2(tdcpme)] (1) and [Ni(NO3)2(tdcpme)] (2), The structure of [NiCl2(tdcpme)] (1) and [Ni(NO3)2(tdcpme)] (2) contain a square planar geometry about the Ni2Cl2 and Ni2O2 cores giving localized symmetry of C2v around the nickel centers. The overall symmetry point group of the compounds is Cs and both Nickels are in a d8, +2 oxidation state. The 31 N of both compounds show only one phosphorus peak indicating that the tdcpme is bound to the metal center in a fluxional bidentate fashion. All cyclohexyl groups are bound in an equatorial fashion to the phosphines of the tdcpme. Elemental analysis of [NiCl2(tdcpme)] and[ni(no3)2(tdcpme)] indicates the purity of the final product as well as the verification of the crystal structure. Scheme 1 : Synthesis of NiCl2(tdcpme)] from NiCl2 6H2O and tdcpme CH 3 eoh NiCl 2.6H 2 O + Toluene = C 6 H 5 CH 2 CH 3 C CH 2 H 2 C Ni Cl Cl Scheme 2: Synthesis of Ni(NO3)2(tdcpme) from Ni(NO3)2 6H2O and tdcpme Ni(NO 3 ) 2.6H 2 O + = C 6 H 5 CH 3 eoh Toluene CH 2 C H 2 C CH 3 CH 2 Ni O N O O N O O O

7 Figure 3: [Ni(Cl3)2(tdcpme)] (1) Selected Bond Distances (Å) and Angles ( ) for [NiCl2(tdcpme)] (1). Ni-Cl(1) 2.227(2) Ni-(1) 2.172(2) Ni-Cl(2) 2.213(1) Ni-(2) 2.183(2) (1)-C(1) 1.835(7) (2)-C(2) 1.840(7) (3)-C(3) 1.861(7) C(1)-C(10) 1.538(10) C(2)-C(10) 1.538(10) C(3)-C(10) 1.570(9) C(10)-C(11) (9) Cl(2)-Ni(1)- Cl(1) 91.51(8) (1)-Ni- (2) 96.53(8) (1)-Ni-Cl(2) 85.84(8) (2)-Ni (9) (1)-Ni-Cl(1) (9) Cl(2) (2)-Ni (8) (1)-C(1) (5) Cl(1) C(10) (2)-C(2) (5) (3)-C(3) (5) C(10) C(10) C(1)-C(10) (6) C(2)-C(10) (6) C(11) C(11) C(3)-C(10) (5) C(1)-C(10) (6) C(11) C(1)-C(10)- C(3) C(2) 107.2(6) C(2)-C(10)- C(3) 105.9(5)

8 Figure 4: [Ni(NO3)2(tdcpme)] (2) Selected Bond Distances (Å) and Angles ( ) for [Ni(NO3)2(tdcpme)] (2). Ni-O(11) 1.938(2) Ni-(1) (8) Ni-O(21) 1.936(2) Ni-(2) (9) (1)-C(1) 1.846(3) (2)-C(2) 1.831(3) (3)-C(3) 1.869(3) C(1)-C(10) 1.531(4) C(2)-C(10) 1.540(4) C(3)-C(10) 1.551(4) C(10)-C(11) 1.525(4) O(21)-Ni(1) (10) O(11) (1)-Ni-(2) 96.79(3) (1)-Ni-O(21) 89.09(7) (2)-Ni-O(21) (6) (1)-Ni-O(11) (7) (2)-Ni-O(11) 86.36(8) (1)-C(1)-C(10) 122.8(2) (2)-C(2)-C(10) 120.8(2) (3)-C(3)-C(10) 116.5(2) C(1)-C(10)-C(11) 112.1(2) C(2)-C(10)-C(11) 111.5(3) C(3)-C(10)-C(11) 110.0(2) C(1)-C(10)-C(2) 111.0(2) C(1)-C(10)- C(3) 104.5(2) C(2)-C(10)-C(3) 107.3(2)

9 esults and discussions esearch into the literature shows that tdppme bonds most often in a tridendate fashion. Both [NiCl2(tdcpme)] (1) and [Ni(NO3)2(tdcpme)] (2) are exceptions and bond in a bidentate fluxional fashion. These molecules are being tested as catalysts for hydrogenation, polymerization and for the synthesis of new chiral molecules. The reactivity and isolation of new complexes of the tris(dicyclohexylphosphinomethyl)ethane ligand will continue. Acknowledgements We would like to thank Grove City College, particularly the Sweezy Undergraduate esearch Fund, for support of this research. Special thanks to Gary Balaich, Air Force Academy, for his technical advice.

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