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Inorganic Chemistry Communications 7 (2004) 880–883

A heteronuclear [nickel(II)–sodium] infinite chain complexderived from 3-{[(2-diethylamino-ethyl)-methyl-amino]-methyl}-

2-hydroxy-5-methyl-benzaldehyde q

Harry Adams, David E. Fenton *, Paul E. McHugh

Department of Chemistry, The University of Sheffield, Dainton Building, Brook Hill, Sheffield S3 7HF, UK

Received 2 March 2004; accepted 7 April 2004

Available online 8 June 2004

Abstract

The asymmetric compartmental proligand HL bearing a tridentate N2O donor set and a bidentate OO donor set has given the

novel heteronuclear [Ni(II)–Na] infinite chain polymer in which the molecular structure has a repeating Na/Ni5 unit of formula

[Ni5Na(L)2(OAc)6(OH)2(BPh4)]n.

� 2004 Elsevier B.V. All rights reserved.

Keywords: Crystal structure; Heteronuclear nickel(II)–sodium complex; Chain polymer

Adams et al. [1] have synthesised homopentanuclear

nickel complexes based on unsymmetrical Schiff base

compartmental ligands. In these complexes, of generic

formula [Ni5L02(OAc)6(OH)2], all ligands have the same

characteristics, an N2O aminic donor compartment and

an NO iminic donor compartment. The iminic sidearm

also contains a pendant arm attached to the imine, but

in most cases this is found to be non-bonding. Thecomplexes contain five Ni(II) ions all exhibiting dis-

torted six co-ordinate octahedral geometry. The penta-

nuclear cluster comprises of two sets of dinuclear units,

self assembled around a central nickel(II) ion and sup-

ported by triply bridging l3-OH units as well as two

bridging syn–syn bidentate acetates and two triply

bridging monodentate acetate units. A schematic

showing the co-ordination modes at the Ni(II) ions isshown in Fig. 1.

In this work, we show that the reaction in methanol of

Ni(OAc)2 and NaBPh4 with 3-{[(2-diethylamino-ethyl)-

methyl-amino]-methyl}-2-hydroxy-5-methyl-benzalde-

qSupplementary data associated with this article can be found, in the

online version, at doi:10.1016/j.inoche.2004.04.025.* Corresponding author. Tel.: +44-114-2229-333; fax: +44-114-2738-

673.

E-mail address: d.fenton@sheffield.ac.uk (D.E. Fenton).

1387-7003/$ - see front matter � 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.inoche.2004.04.025

hyde, HL, a precursor ligand bearing a carbonyl group

instead of a preformed imine ligand and so having ad-

jacent N2O and OO donor sets, gave the heteronuclear

Na/Ni5 chain-type cluster complex (1). Other heteronu-

clear complexes incorporating transition metal ions with

Na cations in the same complex have been prepared by

Winpenny and co-workers, who made Ni(II)/Na supra-

molecular clusters [2,3] and a hexa-copper(II) unit as-sembled around a central Na cation [4], and the group of

Liu [5], who reported a Mn2Na aggregate complex.

OHN O

N

HL

Fig. 2. The full symmetry fragment, [Ni10Na2(L)4(OAc)12-

(OH)4(BPh4)2]. (For clarity, the peripheral carbon skeleton has been

omitted along with the counterions. Each of the terminal Na cations is

at half-occupancy, and the Ni10Na2 fragment repeats as an infinite

long chain at each terminal Na cation).

Fig. 3. The asymmetric unit of the cation from complex (1).

Ni2

OH

Nimine

O

O O

Ni1

NN

OO

Ophenol Ni3

O

Ni5

OH

NimineO

OO

Ni4

N N

OO

Ophenol

O

Fig. 1. Schematic representation of Ni5L02(OAc)6(OH)2.

H. Adams et al. / Inorganic Chemistry Communications 7 (2004) 880–883 881

The proligand HL [6] (150 mg, 0.540 mmol) and

Ni(OAc)2 � 4H2O (269 mg, 1.080 mmol) were refluxed

together in methanol (20 cm3) for 30 min, NaBPh4 (395mg, 1.080 mmol) was added and the resulting solution

allowed to cool to r.t. giving green crystals suitable for

X-ray structure determination. 1 The molecular struc-

ture is a repeating Na/Ni5 unit of formula [Ni5Na-

(L4)2(OAc)6(OH)2(BPh4)]n, formed of pentanuclear

Ni(II) clusters bridged by a Na cation. This unit repeats

as long chains throughout the crystal structure and a

depiction of one of these Na/Ni5 chains is shown inFig. 2. This is the full symmetry fragment of formula

[Ni10Na2(L)4(OAc)12(OH)4(BPh4)2] and for clarity,

many of the peripheral carbon atoms have been left out,

and only the metal centres and co-ordinating donor

atoms have been labelled.

1 Crystal data for complex 1: C68H86BN4NaNi5O18 M ¼ 1574:76,

monoclinic, P2=n, a ¼ 14:821ð2Þ�A, b ¼ 14:562ð2Þ �A, c ¼ 19:517ð3Þ �A,

a ¼ 90�, b ¼ 103:993ð3Þ�, c ¼ 90�, U ¼ 4087:1ð11Þ �A3, Z ¼ 2, l ¼1:198 mm�1, T ¼ 150ð2Þ K, R1 ¼ 0:0589, wR2 ¼ 0:1454 for all 5893

data, 430 parameters).

The full Ni10Na2 fragment is made up of symmetry

equivalent Ni2:5Na0:5 units, hence the bond lengths and

angles are the same for all symmetry generated atoms.The Ni2:5Na0:5 unit is given Fig. 3 to show the num-

bering scheme used.

Proligand HL provides two asymmetric donor com-

partments. At Ni(2) the carbonyl donor compartment is

part of an O6 donor set which is made up by a bridging

phenolate oxygen, O(1), a l3-bridging hydroxide, O(3),

a l2-bridging carbonyl oxygen, O(2) and three l3-bridging acetate anions, O(4), O(6) and O(8). Ni(1), inthe aminic donor compartment, is ligated by an N2O4

donor set, consisting of two tertiary amine nitrogen

donors, N(1) and N(2), a phenolate bridge, O(1), a l3-bridging hydroxide, O(3) and two l3-bridging acetate

anions, O(5), and O(9). Ni(3) has an O6 donor atom set

comprising of two l3-bridging hydroxides, O(3) and its

symmetry equivalent and four l3-bridging acetate mol-

ecules O(8) and O(7) and their symmetry equivalents.The sodium cation, Na(1), has an O6 donor set of two

l2-bridging carbonyl oxygen atoms, O(2) and its sym-

metry equivalent, and four l3-bridging acetates, O(4)

and O(6) and their symmetry equivalents.

All of the metal ions are in six co-ordinate octahedral

environments, with the Na cation having a near perfect

octahedral geometry with all trans-octahedral angles

being 180�. The Ni(II) ions are all distorted octahedrawith Ni(1) being the closest to a regular octahedron and

Ni(3) having the most distorted geometry. Ni(1) and

N(2) are found to be very close together, having a dis-

tance of 2.96309(8) �A, a short metal–metal distance for

Table 1

Selected bond lengths (�A ) and angles (�) at the metals

Bond lengths (�A )

Ni(1)–O(1), 1.976(3); Ni(1)–O(2), 2.051(3); Ni(1)–O(3), 2.026(3); Ni(1)–O(4), 2.077(3); Ni(1)–O(6), 2.023(3); Ni(1)–O(8), 2.106(3); Ni(1)–Ni(2),

2.9630(8); Ni(1)–Ni(3), 3.0093(6); Ni(1)–Na(1), 3.0073(6);

Ni(2)–O(1), 2.075(3); Ni(2)–O(3), 2.043(3); Ni(2)–O(5), 2.060(3); Ni(2)–O(9), 2.074(3); Ni(2)–N(1), 2.116(4); Ni(2)–N(2), 2.207(4); Ni(2)–Ni(3),

3.6904(7); Ni(2)–Na(1), 5.3888(8).

Ni(3)–O(3), 2.018(3); Ni(3)–O(7), Ni(3)–O(8), 2.084(3); 2.056(3); Ni(3)–O(3)#1, 2.018(3); Ni(3)–O(7)#1, 2.056(3); Ni(3)–O(8)#1, 2.084(3);

Ni(3)–Na(1), 5.4384(7);

Na(1)–O(2), 2.543(3); Na(1)–O(4), 2.265(3); Na(1)–O(6), 2.313(3); Na(1)–O(2)#2, 2.420(3); Na(1)–O(4)#2, 2.340(3); Na(1)–O(6)#2, 2.304(3).

Trans Oh – angles (�)O(1)–Ni(1)–O(6), 175.66(11); O(2)–Ni(1)–O(3), 174.85(12); O(4)–Ni(1)–O(8), 171.37(11);

O(1)–Ni(2)–N(2), 172.51(14); O(3)–Ni(2)–N(1), 170.53(13) O(3)–Ni(2)–O(9), 177.20(11);

O(3)–Ni(3)–O(3)#1, 174.56(17); O(7)–Ni(3)–O(8)#1, 169.93(11); O(8)–Ni(3)–O(7)#1, O(2)–Na(1)–O(2)#2, 180.00(14); O(4)–Na(1)–O(4)#2,

180.00(15); 169.93(11); O(6)–Na(1)–O(6)#2, 180.00(15).

Symmetry operators used to generate symmetry equivalent atoms: #1 )x+ 0.5, y,)z + 0.5; #2 )x, )y+ 1,)z.

Ni

OH

OcarbonylO

O O

Ni

NN

OO

Ophenol Ni

O

Ni

OH

OcarbonylO

OO

Ni

N N

OO

Ophenol

O

Na

Na

Fig. 4. Schematic depicting the donor sets around each metal ion.

O OOM M

H

OM M

M

M M

M

Fig. 5. The bridging species present in the complex.

Fig. 6. The repeating unit of the cation [Ni5Na(L)2(O

882 H. Adams et al. / Inorganic Chemistry Communications 7 (2004) 880–883

these type of complexes. This is attributed to the extraone-atom bridging hydroxide present in this system

which draws the two Ni ions to into close proximity.

This rationale is also applicable to the Ni(1)–Ni(3) dis-

tance of 3.0093(8) �A where the hydroxide provides a l3-bridge between the Ni ions. The distance between Ni(2)

and Ni(3) is 3.6904(7) �A, which is indicative of having

only one one-atom bridging unit, the hydroxide, and a

three-atom acetate bridge. The Na–Ni distances are:Na(1)–Ni(1) 3.0073(6) �A ; Na(1)–Ni(2) 5.3888(8) �A and

Na(1)–Ni(3) 5.4383(7) �A. The Na cation has a three-

atom bridge with both Ni(2) and Ni(3), but shares three

one-atom bridges with Ni(1). Selected bond lengths and

angles at the metal centres are given in Table 1 and a

schematic showing the donor sets at each metal is given

in Fig. 4.

The complex incorporates a variety of bridging spe-cies, l2-bridging phenolates, l3-bridging hydroxides and

l3-bridging acetates (Fig. 5). The latter provide a three-

atom bridging unit, with one of the oxygen atoms fur-

ther co-ordinated to a donor unsaturated metal ion.

Complex 1 has a very similar core structure to those

found in the Ni5 complexes outlined in the introduction.

The major modification to the structure of 1 is the co-

ordination of the Na cation. The reaction conditions

Ac)6(OH)2]n from the infinite chain complex.

H. Adams et al. / Inorganic Chemistry Communications 7 (2004) 880–883 883

used to produce the Ni5 complexes did not involve the

presence a counterion to effect complex formation and

crystallisation, so there were no alkali metals present in

solution to co-ordinate to the complex. The ligands used

to form the Ni5 complexes contained Schiff base imineligands, providing a nitrogen donor atom instead of the

carbonyl oxygen atom as in 1. The nitrogen from the

imine has only one lone pair and so once co-ordinated

cannot co-ordinate further to other metal centres or

form bridges between metal ions. The oxygen atom of

the carbonyl group of proligand HL has two lone pairs

and so can form a l2-bridge between a Ni atom and Na

cation thus furnishing the Ni5Na long-chain clustercomplexes. An intriguing aspect of 1 is the repeating

long-chain nature of the crystal structure. The complex

has an array of long chains with a repeat unit of

{[Ni5Na(L)2(OAc)6(OH)2][BPh4]}n as shown in the

packing diagram of the crystal structure (Fig. 6).

Supplementary material

Crystallographic data for the structure reported in

this paper have been deposited with the Cambridge

Crystallographic Data Centre as supplementary publi-

cation No. CCDC 233157. Copies of the data can be

obtained free of charge on application to CCDC, 12

Union Road, Cambridge CB2 1EZ, UK [Fax: (internat.)

+44-1223/336-033; E-mail: deposit@ccda.cam.ac.uk].

Acknowledgements

We thank the EPSRC for support (to P.E.M) and for

funds towards the purchase of the diffractometer.

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