Bis(η5-1-tert-butyl­inden­yl)nickel(II)

Heiko Bauer; Yu Sun; Helmut Sitzmann

doi:10.1107/S1600536811028510

. 2011 Aug 2;67(Pt 9):m1184. doi: 10.1107/S1600536811028510

Bis(η⁵-1-tert-butylindenyl)nickel(II)

Heiko Bauer ^a, Yu Sun ^a, Helmut Sitzmann ^a,^*

PMCID: PMC3200892 PMID: 22065650

Abstract

The title compound, [Ni(C₁₃H₁₅)₂], shows a slightly distorted sandwich structure with two independent molecules in the asymmetric unit. Both Ni atoms are located on crystallographic centres of inversion.

Related literature

For the synthetic procedure of the analogous indenylcobalt complex, see: Gou et al. (2007 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶). For the use of bis(indenyl)nickel(II) complexes as starting compounds for poly- and oligomerization catalysts, see: Xie et al. (2009 ▶); Fontaine & Zargarian et al. (2004 ▶). For the indenyl effect in S_N1, S_N2 and other reactions, see: Elschenbroich (2008 ▶); Rerek & Basolo (1984 ▶); Rerek et al. (1983 ▶), O’Connor & Casey (1987 ▶); Turaki et al. (1988 ▶); Caddy et al. (1978 ▶); Bönnemann (1985 ▶); Marder et al. (1988 ▶).

Experimental

Crystal data

[Ni(C₁₃H₁₅)₂]
M _r = 401.21
Triclinic,
a = 9.8116 (5) Å
b = 10.9631 (7) Å
c = 11.1658 (7) Å
α = 68.800 (6)°
β = 67.085 (5)°
γ = 85.212 (4)°
V = 1029.10 (11) Å³
Z = 2
Cu Kα radiation
μ = 1.38 mm⁻¹
T = 150 K
0.11 × 0.07 × 0.04 mm

Data collection

Oxford Diffraction Xcalibur Sapphire3 Gemini ultra diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010 ▶) T _min = 0.675, T _max = 1.000
8813 measured reflections
3283 independent reflections
2838 reflections with I > 2σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.027
wR(F ²) = 0.075
S = 1.07
3283 reflections
253 parameters
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2010 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2010 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SCHAKAL99 (Keller, 1999 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811028510/im2294sup1.cif

e-67-m1184-sup1.cif^{(24.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811028510/im2294Isup2.hkl

e-67-m1184-Isup2.hkl^{(157.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

The catalytic activity of indenylnickel(II) complexes has stimulated recent research activity. It is e.g. possible to oligomerize phenylsilane in the presence of a methylindenylnickel(II) phosphine complex (Fontaine & Zargarian, 2004). N-heterocyclic carbene complexes of indenylnickel(II) chloride have been shown to polymerize styrene (Xie et al., 2009). The starting compounds for these complexes are bis(indenyl)nickel(II) and bis(1-methylindenyl)nickel(II). With the well known indenyl effect (Elschenbroich, 2008) based on a slip-fold distortion of the indenyl ligand from η⁵ to η³ coordination, which greatly enhances the reactivity in S_N1 and S_N2 substitution reactions (Rerek & Basolo 1984, Rerek et al. 1983; O'Connor & Casey, 1987; Turaki et al., 1988) and other reactions, (Caddy et al., 1978; Bönnemann, 1985; Marder et al., 1988) the as yet unknown bis(η⁵-1-tert-butylindenyl)nickel(II) complex became interesting to us as a promising starting compound.

The title compound was synthesized from lithium 1-tert-butylindenide and nickel(II) bromide dimethoxyethane complex and crystallized as dark red prisms. In the structure shown here, the nickel atom is bound to the carbon atoms of the five-membered ring of the ligand by a distorted η⁵-coordination. The metal ion is positioned on a crystallographic centre of inversion and the two indenyl ligands are therefore arranged in a staggered coordination with a rotation angle of 180°. As known from similar complexes (Gou et al., 2007), the lengths of the five Ni—C bonds are split in two sets. The three shorter bond distances are 2.124 (1) Å, 1.994 (2) Å and 2.049 (2) Å, the two longer bond distances are 2.460 (2) Å and 2.505 (1) Å, which is even longer than for the Co complex (Gou et al., 2007). The distance between the nickel centre and the centroid of the five-membered ring is 1.7950 (8) Å. The folding angle of 4.28 (7)° shows a slightly smaller value than for unsubstituted indenyl complexes (Rerek et al., 1983). The two different bond length ranges are in accordance with the usual η²+η³-coordination of the indenyl ligand resulting from the reluctant participation of the benzene ring in the ligand-metal electron donation (Rerek et al., 1983). The bond between C1 and C10 is bending out 7.2 (1)° of the ring plane.

Experimental

To a stirred solution of 1-tert-butylindene (862 mg, 5.0 mmol) in diethyl ether (10 ml) a solution of n-BuLi (1.6 mol/l, 3.44 ml, 5.5 mmol) in hexane was added slowly at 0 °C. Stirring was continued for 19 h at room temperature, then the solvent was removed in vacuo. The resulting white precipitate was suspended in pentane, cooled overnight in a fridge, filtered and washed with pentane. The lithium 1-tert-butylindenide was suspended in THF (10 ml) and NiBr₂ × dme (1.54 g, 5.0 mmol) was added. The mixture was stirred for 24 h at room temperature. The solvent was removed in vacuo and the residue extracted with pentane. The product was obtained as dark red prisms at -30 °C (323 mg, 16%).