Cobalt and nickel complexes of open-chain thioether ligands terminated by salicylaldimine functionality

1174

Cobalt and nickel complexes of open-chain

thioether ligands terminated by salicylaldimine

functionality^*

C. Robert Lucas, John M.D. Byrne, Julie L. Collins, Louise N. Dawe, and

David O. Miller

Abstract: Syntheses of 1,11-bis(salicylaldimine)-3,6,9-trithiaundecane (H₂L1), 1,11-bis(salicylaldimine)-6-oxa-3,9-dithiaun-

decane (H₂L2), and 1,8-bis(salicylaldimine)-3,6-dithiaundecane (H₂L3), their nickel complexes [Ni(L1)]·H₂O (I),

[Ni(HL2)][OAc] (II), [Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III), [Ni(HL1-sal)]Cl₂·H₂O (IV), [Ni(HL2-sal)]Cl₂·CH₃OH

(V), [Ni(L3-sal)Cl]·H₂O (VI), {[Ni(HL1-sal)]Br₂}₂{[Ni(L1-sal)]Br}·H₂O (VII), {[Ni(HL2-sal)]Br₂}₂{[Ni(L2-sal)]Br}·2CH₃OH

(VIII), {[Ni(HL3-sal)Br]Br}[Ni(L3-sal)Br]·2CH₃OH (IX), [Ni(HL3-sal)Br]Br·CH₃OH (X), [Ni(HL3)Br]·2H₂O (XI),

[Ni(HL1)]₂[BF₄]₂·5H₂O (XII), [Ni(HL2)]₂[BF₄]₂·3H₂O (XIII), [Ni(HL3)]₂[BF₄]₂·CH₃CN (XIV), and [Ni(HL3)]₂[BF₄]₂·3H₂O

(XV) and their cobalt complexes [Co(L1-sal)][BF₄]₂(XVI), [Co(L2)][OAc]·3H₂O (XVII), [Co(L3)][OAc]·3H₂O (XVIII),

[Co(L3)][BF₄] (XIX), and [Co(L3-sal)(CH₃OH)][BF₄]₂·CH₃OH (XX) are reported. Single crystal X-ray structural studies for

III, XIV, XVI, and XIX are described. Cyclic voltammograms of the ligands and of I, II, III, VII, VIII, X, XIV, and

XIX are discussed. Electronic spectra of the ligands and complexes are discussed.

Key words: cobalt and nickel complexes, thioether, salicylaldimine ligands, X-ray structure, cyclic voltammetry, UV–vis

spectra.

Résumé : On décrit les synthèses du 1,11-bis(salicylaldimine)-3,6,9-trithiaundécane (H₂L1), 1,11-bis(salicylaldimine)-6-oxa-

3,9-dithiaundécane (H₂L2) et du 1,8-bis(salicylaldimine)-3,6-dithiaundécane (H₂L3), de leurs complexes de nickel [Ni(Ll)]·H₂O

(I), [Ni(HL2)][OAc] (II), [Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III), [Ni(HL1-sal)]Cl₂·H₂O (IV), [Ni(HL2-sal)]Cl₂·CH₃OH

(V), [Ni(L3-sal)Cl]·H₂O (VI), {[Ni(HL1-sal)]Br₂}₂{[Ni(L1-sal)]Br}·H₂O (VII), {[Ni(HL2-sal)]Br₂}₂{[Ni(L2-sal)]Br}·2CH₃OH

(VIII), {[Ni(HL3-sal)Br]Br}₂[Ni(L3-sal)Br]·2CH₃OH (IX), [Ni(HL3-sal)Br]Br·CH₃OH (X), [Ni(HL3)Br]·2H₂O (XI),

[Ni(HL1)]₂[BF₄]₂·5H₂O (XII), [Ni(HL2)₂[BF₄]₂·3H₂O (XIII), [Ni(HL3)₂[BF₄]₂·CH₃CN (XIV) et [Ni(HL3)₂]₂[BF₄]₂·3H₂O

(XV) ainsi que de leurs complexes de cobalt [Co(L1-sal)][BF₄]₂(XVI), [Co(L2)][OAc]·3H₂O (XVII), [Co(L3)][OAc]·3H₂O

(XVIII), [Co(L3)][BF₄] (XIX) et [Co(L3-sal)(CH₃OH)][BF₄]₂·CH₃OH (XX). On décrit les structures des composés III,

XIV, XVI et XIX telles que déterminées par diffraction des rayons-X. On discute des résultats obtenus par voltampérométrie

cyclique des ligands I, II, III, VII, VIII, X, XIV et XIX. On discute aussi des spectres électroniques des ligands et des com-

plexes.

Mots‐clés : complexes du cobalt et du nickel, thioéther, ligands de la salicylaldimine, structure par diffraction des rayons X,

voltampérométrie cyclique, spectres UV–visible.

[Traduit par la Rédaction]

roscopic level. Current examples could be changes observed

in photoluminescence^3,4or magnetic susceptibility^5,6of bulk

samples of matter induced by structural changes at the mo-

lecular level. As part of our continuing interest^7–9in the in-

fluence of ligand structure on properties of thioether–metal

complexes, we now report studies of complexes in which

open-chain ligands (Fig. 1) are terminated by salicylaldimine

functions. These ligands are related to similar open-chain li-

gands terminated by alkyl,¹⁰pyridyl,¹¹thienyl,¹²pyrazolyl,¹³

and benzamidazolyl¹³functionalities that we have described

in earlier work and it is therefore of interest to explore

Introduction

Metal complexes of salicylaldimine ligands continue to be

of interest for several reasons, not the least of which is their

potential for use in a variety of applications such as sensor¹

or liquid crystal²technology. Furthermore, future applications

of metal complexes in areas such as biomodeling, materials

science, catalysis, communications, and data storage require

inter alia the ability to adjust properties of existing substan-

ces. To do so in a rational manner requires understanding of

the consequences of structural changes at the molecular level

on properties that manifest themselves primarily at the mac-

Received 5 December 2010. Accepted 14 April 2011. Published at www.nrcresearchpress.com/cjc on 7 September 2011.

C.R. Lucas, J.M. Byrne, J.L. Collins, L.N. Dawe, and D.O. Miller. Department of Chemistry, Memorial University of Newfoundland,

St. John’s, NL A1B 3X7, Canada.

Corresponding author: C. Robert Lucas (e-mail: rlucas@mun.ca).

^*This article has a companion paper in this issue (doi: 10.1139/v11-083).

Can. J. Chem. 89: 1174–1189 (2011)

doi:10.1139/V11-081

Published by NRC Research Press

Lucas et al.

1175

Fig. 1. Ligands and their position identifiers used in this study.

perature by using a Cypress Systems, Inc., CS-1087 com-

puter-controlled potentiostat. Solution concentrations were

10^–3mol/L in complex and 0.1 mol/L in supporting electro-

lyte (tetraethylammonium perchlorate). Voltammograms were

recorded in acetonitrile by using a glassy carbon working

electrode that was prepolished with 0.3 mm Al₂O₃, a plati-

num counter electrode, and an aqueous saturated calomel

reference electrode checked periodically relative to a 1.0 ×

10^–3mol/L solution of ferrocene in acetonitrile containing

0.1 mol/L tetraethylammonium perchlorate for which the fer-

rocene/ferrocenium reduction potential was 400 mV. The

reference electrode was separated from the bulk of the solu-

tion by a porous Vycor tube. Junction potential corrections

were not used. X-ray diffraction data were collected on either

a Rigaku AFC6S or a Rigaku AFC8 Saturn 70 diffractometer

using graphite-monochromated Mo Ka radiation. Analyses

were performed by Canadian Microanalytical Service, Ltd.

Preparative details — Ligands

C₂₂H₂₈N₂O₂S₃(H₂L1)

Sodium (8.91 g, 0.388 mol) was dissolved in commercial

absolute ethanol (400 mL) under an atmosphere of dry nitro-

gen, and 2-mercaptoethyl sulfide (15.0 g, 0.972 mol) was

added slowly. The resulting mixture was heated to reflux and

a solution of 2-chloroethylamine hydrochloride (22.6 g,

0.194 mol) in commercial absolute ethanol (20 mL) was

added dropwise with stirring. Reflux was continued for

45 min, during which a white precipitate appeared. Salicylal-

dehyde (23.7 g, 0.194 mol) was added, instantly giving a

bright yellow solution. Reflux was continued for 48 h and

on cooling a thick yellow precipitate deposited. Solvent was

removed under reduced pressure via rotary evaporator and

the residue taken up in dichloromethane (150 mL). Undis-

solved sodium chloride was filtered away. The dichlorome-

thane solution was carefully reduced in volume via a rotary

evaporator until cloudy and then placed in the refrigerator

overnight. The resulting crystals were collected by suction

filtration, washed with ice-cold acetonitrile (3 × 5 mL) and

crystallized from hot acetonitrile (300 mL) with storage over-

night at –20 °C. The product was collected by filtration and

washed with ice-cold acetonitrile (3 × 15 mL) to give bright

yellow shiny leaflets (36.5 g, 83% yield) melting over the

range 110.7–111.1 °C. UV–vis (CH₃CN) l_maxin nm (3 in

mol^–1L cm^–1): 225 (10 800), 255 (4580), 316 (1740), 405

changes arising from alteration to salicylaldimine of the li-

gands’ terminal groups. In a related report, we address this

question for complexes of copper,¹⁴whereas the current pa-

per investigates complexes of cobalt and nickel. Ligands

used in this study are shown in Fig. 1.

Experimental

All reagents were obtained from the Sigma-Aldrich Chem-

ical Co., Inc., and used without further purification. Solvents

were ACS grade and were used without purification prior to

use. NMR spectra were obtained on a Brüker AVANCE 500

1

(450). H NMR (CDCl₃, position identification from Fig. 1)

d: 2.74 (s, 8H, C10, C11), 2.88 (t, J = 7.2 Hz, 4H, C9),

3.79 (t, J = 7.2 Hz, 4H, C8), 6.88 (t, J = 8.5 Hz, 2H, C4),

6.96 (d, J = 9.5 Hz, 2H, C5), 7.26 (d, J = 7.0 Hz, 2H, C2),

7.31 (t, J = 8.5 Hz, 2H, C3), 8.37 (s, 2H, C7), 13.2 (s, 2H,

OH). ¹³C{¹H} NMR d: 32.60 (C10), 32.82 (C9), 33.41

(C11), 59.61 (C8), 117.20 (C4), 118.83 (C6), 118.91 (C2),

131.64 (C5), 132.63 (C3), 161.26 (C1), 166.24 (C7). Mass

spectrum APCI(+) calcd for M+ 1: 449.1; found: 449.2.

Anal. calcd for C₂₂H₂₈N₂O₂S₃: C 58.89, H 6.29, N 6.24,

S 21.44; found: C 58.94, H 6.44, N 6.29, S 22.21.

1

instrument at 500.133 MHz for H and 125.770 MHz for

¹³C. All NMR spectra were run in CDCl₃as the solvent with

tetramethylsilane as the internal standard. All ¹³C spectra

were broadband decoupled. Melting points were obtained on

a Fisher-Johns melting point apparatus. Electronic spectra

were obtained in acetonitrile solutions that were 2.0 × 10^–3

and 2.0 × 10^–5mol/L in solute using a Hewlett-Packard

8452A diode array UV–vis spectrophotometer. Other instru-

ments used were a Brüker Tensor FTIR IR spectrometer

equipped with a PIKE technologies MIRacle single reflection

zinc selenide crystal HATR and an Agilent 1100 Series

liquid chromatograph with either an SL MSD trap or a

1946A quadrupole detector. Electrochemical measurements

were carried out under a nitrogen atmosphere at room tem-

C₂₂H₂₈N₂O₃S₂(H₂L2)

The procedure was the same as for H₂L1 except that

2-mercaptoethyl ether was used instead of 2-mercaptoethyl

sulfide. Final recrystallization was from hot acetonitrile –

Published by NRC Research Press

1176

Can. J. Chem. Vol. 89, 2011

chloroform (150 mL : 50 mL) with storage overnight at –20 °C.

The product collected by suction filtration was washed with

ice-cold methanol (3 × 5 mL) and then ether (3 × 5 mL) to

give bright yellow shiny needles (64% yield) melting over

the range 76.8–78.0 °C. A second crop of bright yellow

needles (27%) that melted over the same range was recov-

ered from the mother liquor after further storage at –20 °C.

mol^–1L cm^–1): 280 (1350), 310 (1500), 408 (1400), 610

(55). Mass spectrum APCI(+) calcd for M – H₂O + 1,

[C₂₂H₂₇N₂NiO₂S₃]⁺m/z: 505.0; found m/z: 505.0. Anal. calcd

for C₂₂H₂₈N₂NiO₃S₃: C 50.49, H 5.39, N 5.35; found: C 50.89,

H 5.09, N 5.09.

[Ni(HL2)][OAc] (II)

¹H NMR (CDCl₃, position identification from Fig. 1) d:

2.73 (t, J = 5.5 Hz, 4H, C10), 2.89 (t, J = 8.5 Hz, 4H,

C9), 3.64 (t, J = 5.5 Hz, 4H, C11), 3.79 (t, J = 5.0 Hz,

4H, C8), 6.87 (t, J = 7.0 Hz, 2H, C4), 6.95 (d, J =

8.5 Hz, 2H, C5), 7.25 (d, J = 7.5 Hz, 2H, C2), 7.31 (m,

2H, C3), 8.36 (s, 2H, C7), 13.3 (s, 2H, OH). ¹³C{¹H}

NMR d: 32.20 (C10), 33.71 (C9), 59.65 (C8), 71.10 (C11),

117.28 (C4), 118.82 (C6), 118.89 (C2), 131.60 (C5),

132.60 (C3), 161.27 (C1), 166.12 (C7). Mass spectrum

APCI(+) calcd for M + 1: 433.1; found: 433.2. Anal. calcd

for C₂₂H₂₈N₂O₃S₂: C 61.08, H 6.52, N 6.48, S 14.82;

found: C 60.89, H 6.51, N 6.49, S 14.69.

H₂L2 (0.72 g, 1.7 mmol) dissolved in warm (~40 °C) ace-

tonitrile (25 mL) was mixed with nickel(II) acetate trihydrate

(0.42 g, 1.8 mmol) in warm (~40 °C) methanol (25 mL) to

give a dark green solution. The solvent was evaporated to

give a dark green glassy film that was triturated in acetoni-

trile (2 mL) in which it was slightly soluble. The residue

was collected by filtration and dried in air to give a fine

green powder that was dissolved in chloroform (50 mL), con-

centrated to 20 mL via a rotary evaporator, filtered, and then

added dropwise with stirring to cold ether (350 mL) to give a

bright green precipitate. This was collected in a sintered glass

crucible, washed with ether (3 × 5 mL), and then dried to

give a green powder (0.26 g, 28% yield). UV–vis (CH₃CN)

l_maxin nm (3 in mol^–1L cm^–1): 280 (sh), 308 (1450), 340

(sh), 400 (1500), 610 (54). Mass spectrum APCI(+) calcd

for M – OAc, [C₂₂H₂₇N₂NiO₃S₂]⁺m/z: 489.1; found m/z:

489.0. Anal. calcd for C₂₄H₃₀N₂NiO₅S₂: C 52.48, H 5.50,

N 5.10; found: C 52.63, H 5.41, N 5.29.

C₂₀H₂₄N₂O₂S₂(H₂L3)

The procedure is similar to that for H₂L1 except that 1,2-

ethanedithiol was used instead of 2-mercaptoethyl sulfide and

the initial crude residue was taken up in chloroform, filtered,

reduced in volume until cloudy, and then refrigerated. The re-

sulting solid was collected, washed with a little ice-cold

chloroform, dissolved in chloroform, and washed with deion-

ized water. The organic layer was dried over anhydrous

MgSO₄and filtered. Upon concentrating and storing at –20 °C

a bright yellow precipitate separated was collected and then

washed with ice-cold chloroform and then ether to give

bright yellow shiny leaflets (86.2% yield) melting over the

range 108.7–109.1 °C. UV–vis (CH₃CN) l_maxin nm (3 in

mol^–1L cm^–1): 230 (12 630), 258 (4240), 313 (1174), 398

{[Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III)

H₂L3 (0.66 g, 1.7 mmol) dissolved in warm (~40 °C) 1:1

acetonitrile/methanol (40 mL) was mixed with nickel(II) ace-

tate trihydrate (0.42 g, 1.8 mmol) in warm (~40 °C) methanol

(20 mL) to give a dark brown-green solution. Within a few

hours the colour became brown-purple. The solvent was

evaporated slowly in air to give a brown residue that was tri-

turated in acetonitrile (2 mL) in which it was slightly soluble.

The solid was collected by filtration, washed with cold aceto-

nitrile (3 × 2 mL), and then dried in air to give a fine brown-

green powder. The powder was dissolved in methanol

(100 mL), concentrated via a rotary evaporator to 20 mL, fil-

tered, and then the filtrate was added dropwise with stirring

to cold ether to give a yellow-green precipitate. This was col-

lected in a sintered glass crucible and washed with ether (3 ×

5 mL) and then dried to give a yellow-green powder (0.50 g,

55% yield). Alternatively, slow evaporation of the methanol

filtrate produced X-ray quality dark green crystals. UV–vis

(CH₃CN) l_maxin nm (3 in mol^–1L cm^–1): 290 (1354), 345

(sh), 383 (1450), 577 (41). Mass spectrum APCI(+) calcd

for [Ni(HL3)], [C₂₀H₂₃N₂NiO₂S₂]⁺m/z: 445.1; found m/z:

445.0. Anal. calcd for C₆₈H₈₈N₆Ni₃O₁₇S₆: C 50.11, H 5.44,

N 5.16; found: C 49.94, H 5.31, N 5.12.

1

(350). H NMR (CDCl₃, position identification from Fig. 1)

d: 2.75 (s, 4H, C10), 2.88 (t, J = 5.0 Hz, 4H, C9), 3.77 (t,

J = 5.0 Hz, 4H, C8), 6.88 (t, J = 7.0 Hz, 2H, C4), 6.96 (d,

J = 10.5 Hz, 2H, C5), 7.26 (d, J = 5.0 Hz, 2H, C2), 7.30 (t,

J = 10.0 Hz, 2H, C3), 8.33 (s, 2H, C7), 13.2 (s, 2H, OH).

¹³C{¹H} NMR d: 32.82 (C10), 33.60 (C9), 59.68 (C8),

117.18 (C4), 118.79 (C6), 118.83 (C2), 131.63 (C5), 132.63

(C3), 161.28 (C1), 166.21 (C7). Mass spectrum APCI(+)

calcd for M + 1 m/z: 389.1; found m/z: 389.2. Anal. calcd

for C₂₀H₂₄N₂O₂S₂: C 61.82, H 6.23, N 7.21, S 16.51; found:

C 61.72, H 6.11, N 7.41, S 16.15.

Preparative details — Complexes

[Ni(L1)]·H₂O (I)

H₂L1 (1.0 g, 2.2 mmol) dissolved in warm (~40 °C) meth-

anol (25 mL) was mixed with nickel(II) acetate trihydrate

(0.56 g, 2.4 mmol) in warm (~40 °C) methanol (25 mL) to

give a dark green solution. The solvent was evaporated and

the residue washed with methanol (3 × 5 mL) to give a light

green powder that was dissolved in N,N′-dimethylformamide

(30 mL). The solution was filtered and then added dropwise

with stirring to cold deionized water (300 mL) to give a thick

yellow-green precipitate that was collected in a sintered glass

crucible, washed with acetone (2 × 5 mL) and then ether

(5 × 5 mL), and then dried to give a brown-green powder

(0.74 g, 64% yield). UV–vis (CH₃CN) l_maxin nm (3 in

[Ni(HL1-sal)]Cl₂·H₂O (IV)

H₂L1 (1.0 g, 2.2 mmol) dissolved in warm (~40 °C) aceto-

nitrile (25 mL) was mixed with nickel(II) chloride hexahy-

drate (0.52 g, 2.2 mmol) in warm (~40 °C) methanol

(25 mL) to give a dark green solution. The solvent was

evaporated slowly in air to give a green glassy residue that

was triturated in acetonitrile (2 mL) in which it was slightly

soluble. The solid, which is insoluble in acetone and chloro-

form, was collected by filtration and dried in air to a fine

green powder. This powder was dissolved in hot methanol

(100 mL). The solution was concentrated via a rotary

Published by NRC Research Press

Lucas et al.

1177

evaporator to 20 mL, filtered, and then added dropwise with

stirring to cold ether (300 mL) to give a light green precipi-

tate. This was collected in a sintered glass crucible, washed

with ether (3 × 5 mL), and then dried in air to give a light

green powder (0.94 g, 86% yield). UV–vis (CH₃CN) l_maxin

nm (3 in mol^–1L cm^–1): 293 (1500), 323 (1500), 370 (1400),

406 (sh), 602 (40). Mass spectrum APCI(+) calcd for

[Ni(L1-sal)] (sal = C₇H₃O), [C₁₅H₂₃N₂NiOS₃]⁺m/z: 401.0;

found m/z: 401.0. Anal. calcd for C₁₅H₂₆Cl₂N₂NiO₂S₃: C 36.61,

H 5.32, N 5.69; found: C 36.70, H 4.95, N 5.41.

carded and the filtrate evaporated slowly in air to produce a

few black crystals and a green glassy residue. The solids

were washed with acetonitrile (6 × 5 mL portions), which

dissolved the crystals leaving behind the glassy residue.

Slow evaporation of the solution produced very dark green

(nearly black) crystals analyzed as Ni(HL3)Br·2H₂O (XI).

The green glassy residue was triturated in acetonitrile (5 mL)

and collected by filtration as a fine green powder analyzed as

Ni(HL3-sal)Br₂·CH₃OH (X). This powder could be dissolved

in methanol (80 mL) to give a brown solution, which when

concentrated via a rotary evaporator to 10 mL, filtered, and

added dropwise with stirring to cold ether (300 mL) yielded

a pale-green, almost white precipitate, which was collected,

washed with ether (3 × 5 mL), and then dried in air to give

IX (0.26 g, 31% yield). UV–vis (CH₃CN) l_maxin nm (3 in

mol^–1L cm^–1): 284 (1200), 320 (1200), 384 (1300). Mass

spectrum APCI(+) calcd for [Ni(L3-sal)], [C₁₃H₁₉N₂NiOS₂]⁺

m/z: 341.0; found m/z: 341.0. Anal. calcd for

C₂₈H₄₇Br₃N₄Ni₂O₄S₄: C 34.00, H 4.79, N 5.66; found: C

34.18, H 4.41, N 5.70.

[Ni(HL2-sal)]Cl₂·CH₃OH (V)

The procedure is the same as for IV to give a green pow-

der (0.78 g, 73% yield). UV–vis (CH₃CN) l_maxin nm (3 in

mol^–1L cm^–1): 287 (1300), 320 (1400), 380 (1100), 595

(45). Mass spectrum APCI(+) calcd for [Ni(L2-sal)],

[C₁₅H₂₃N₂NiO₂S₂]⁺m/z: 385.0; found m/z: 385.0. Anal. calcd

for C₁₆H₂₈Cl₂N₂NiO₃S₂: C 39.21, H 5.76, N 5.72; found:

C 38.89, H 5.23, N 5.74.

[Ni(L3-sal)Cl]·H₂O (VI)

The procedure is the same as for III to give a light green

powder (0.59 g, 89% yield). Mass spectrum APCI(+) calcd

for [Ni(L3-sal)], [C₁₃H₁₉N₂NiOS₂]⁺m/z: 341.0; found m/z:

341.0. Anal. calcd for C₁₃H₂₁ClN₂NiO₂S₂: C 39.47, H 5.35,

N 7.08, Ni 14.84; found: C 39.76, H 4.84, N 6.95, Ni 14.20.

[Ni(HL3-sal)Br]Br·CH₃OH (X)

For preparative details see IX; 0.46 g, 51% yield. Mass spec-

trum APCI(+) calcd for [HL3-sal + 1], [C₁₃H₂₀N₂OS₂]⁺m/z:

285.1; found m/z: 285.1. Anal. calcd for C₁₄H₂₄Br₂N₂NiO₂S₂:

C 31.43, H 4.52, N 5.24; found: C 31.67, H 4.36, N 5.34.

{[Ni(HL1-sal)]Br₂}₂{[Ni(L1-sal)]Br}·H₂O (VII)

[Ni(HL3)Br]·2H₂O (XI)

H₂L1 (1.0 g, 2.2 mmol) dissolved in warm (~40 °C) aceto-

nitrile (25 mL) was mixed with nickel(II) bromide monohy-

drate (0.52 g, 2.2 mmol) in warm (~40 °C) methanol

(25 mL) to give a green solution and a light green precipi-

tate. The solid was collected by filtration and dried in air to

a fine green powder. This powder was dissolved in hot meth-

anol (80 mL). The solution was concentrated via a rotary

evaporator to 15 mL, filtered, and then added dropwise with

stirring to cold ether (300 mL) to give a light green precipi-

tate that was collected, washed with ether (3 × 5 mL), and

then dried in air to give a green powder (0.70 g, 59% yield).

Mass spectrum APCI(+) calcd for [Ni(L1-sal)],

[C₁₅H₂₃N₂NiOS₃]⁺m/z: 401.0; found m/z: 401.0. Calcd for

[H₂L1-sal)] (sal = C₇H₃O), [C₁₅H₂₅N₂OS₃]⁺m/z: 345.1;

found m/z: 345.1. Anal. calcd for C₄₅H₇₃Br₅N₆Ni₃O₄S₉: C

33.23, H 4.52, N 5.17, Br 24.57, Ni 10.83; found: C 32.87,

H 4.48, N 5.19, Br 24.73, Ni 10.1.

For preparative details see IX; 0.16 g, 15% yield. Mass spec-

trum APCI(+) calcd for [Ni(H₂L3)Br], [C₂₀H₂₄BrN₂NiO₂S₂]⁺

m/z: 525.0; found m/z: 525.0. Calcd for [Ni(HL3)],

[C₂₀H₂₃N₂NiO₂S₂]⁺m/z: 445.0; found m/z: 445.0. Calcd for

[H₂L3 + 1], [C₂₀H₂₅N₂O₂S₂]⁺m/z: 389.1; found m/z: 389.1.

Anal. calcd for C₂₀H₂₇BrN₂NiO₄S₂: C 42.73, H 4.84, N 4.98,

Ni 10.44; found: C 42.66, H 4.66, N 4.90, Ni 12.20.

[Ni(HL1)]₂[BF₄]₂·5H₂O (XII)

The procedure is the same as for X except that the fine

green powder was dissolved in hot acetonitrile (100 mL),

concentrated via a rotary evaporator to 20 mL, filtered, and

then added dropwise with stirring to cold ether (300 mL).

This produced a yellow-green precipitate that was collected,

washed with ether (3 × 5 mL), and then dried in air to give

a fine pale green powder (0.51 g, 36% yield). UV–vis

(CH₃CN) l_maxin nm (3 in mol^–1L cm^–1): 283 (sh), 320

(1485), 340 (sh), 380 (1207), 420 (sh), 620 (25). Mass spec-

trum APCI(+) calcd for [NiHL1], [C₂₂H₂₇N₂NiO₂S₃]⁺m/z:

505.0; found m/z: 505.0. Calcd for [NiL1-sal],

[C₁₅H₂₃N₂NiOS₃]⁺m/z: 401.0; found m/z: 401.0. Calcd for

[H₂L1-sal], [C₁₅H₂₅N₂OS₃]⁺m/z: 345.1; found m/z: 345.1.

Anal. calcd for C₄₄H₆₄B₂F₈N₄Ni₂O₉S₆: C 41.40, H 5.05, N

4.39; found: C 41.26, H 4.47, N 4.79.

{[Ni(HL2-sal)]Br₂}₂{[Ni(L2-sal)]Br}·2CH₃OH (VIII)

The procedure is the same as for VII to give a green pow-

der (0.39 g, 33% yield). Mass spectrum APCI(+) calcd for

[Ni(L2-sal)], [C₁₅H₂₃N₂NiO₂S₂]⁺m/z: 385.0; found m/z:

385.0. Calcd for [H₂L2-sal)], [C₁₅H₂₅N₂O₂S₂]⁺m/z: 329.1;

found m/z: 329.1. Anal. calcd for C₄₇H₇₉Br₅N₆Ni₃O₈S₆: C

34.76, H 4.90, N 5.17, Br 24.60, Ni 10.8; found: C 34.37, H

4.80, N 5.08, Br 24.68, Ni 10.8.

[Ni(HL2)]₂[BF₄]₂·3H₂O (XIII)

{[Ni(HL3-sal)Br]Br}[Ni(L3-sal)Br]·2CH₃OH (IX)

The procedure is the same as for XII except that trituration

is in ether and the final product is a fine pale green powder

(0.60 g, 45% yield). UV–vis (CH₃CN) l_maxin nm (3 in

mol^–1L cm^–1): 283 (sh), 320 (1527), 378 (1431), 410 (sh),

600 (50). Mass spectrum APCI(+) calcd for [NiHL2],

H₂L3 (0.65 g, 1.7 mmol) dissolved in warm (~40 °C) ace-

tonitrile (40 mL) was mixed with nickel(II) bromide monohy-

drate (0.40 g, 1.7 mmol) in warm (~40 °C) methanol

(20 mL) to give a small amount of white precipitate in a light

brown solution. The solid was separated by filtration and dis-

Published by NRC Research Press

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Can. J. Chem. Vol. 89, 2011

[C₂₂H₂₇N₂NiO₃S₂]⁺m/z: 489.1; found m/z: 489.0. Calcd for

[H₃L2], [C₂₂H₂₉N₂O₃S₂]⁺m/z: 433.2; found m/z: 433.1.

Calcd for [NiL2-sal] (sal = C₇H₃O), [C₁₅H₂₃N₂NiO₂S₂]⁺

m/z: 385.0; found m/z: 385.0. Calcd for [H₂L2-sal)] (sal =

C₇H₃O), [C₁₅H₂₅N₂O₂S₂]⁺m/z: 329.1; found m/z: 329.1.

Anal. calcd for C₄₄H₆₀B₂F₈N₄Ni₂O₉S₄: C 43.74, H 5.00, N

4.64; found: C 43.88, H 4.63, N 4.71.

[Co(L2)](OAc)·3H₂O (XVII)

H₂L2 (0.96 g, 2.2 mmol) dissolved in warm (~40 °C) ace-

tonitrile (25 mL) was mixed with cobalt(II) acetate tetrahy-

drate (0.56 g, 2.2 mmol) in warm (~40 °C) methanol

(25 mL) to produce a dark orange solution that quickly be-

came dark red. The solvent was evaporated slowly in air to

give a dark red-purple film that was triturated with ether

(3 mL), giving a black powder that was collected, washed

with ether (3 × 5 mL), and then dried in air to a dark purple

powder. The powder was dissolved in hot (~60 °C) methanol

(15 mL) and the solution concentrated via a rotary evaporator

to 10 mL, filtered, and then added dropwise with stirring to

cold ether (300 mL) to produce a purple precipitate that was

collected, washed with ether (3 × 5 mL), and then dried in

air to give a light purple powder (1.05 g, 80% yield). UV–

vis (CH₃CN) l_maxin nm (3 in mol^–1L cm^–1): 650 (40), 476

(110), 384 (600), 312 (930). Mass spectrum APCI(+) calcd

for [CoL2 + H], [C₂₂H₂₇CoN₂O₃S₂]⁺m/z: 490.1; found m/z:

490.0. Anal. calcd for C₂₄H₃₅CoN₂O₈S₂: C 47.84, H 5.85, N

4.65; found: C 47.70, H 5.55, N 4.52.

[Ni(HL3)]₂[BF₄]₂·CH₃CN (a) (XIV) and

[Ni(HL3)]₂[BF₄]₂·3H₂O (b) (XV)

For (a), the procedure for (b) was followed except that the

acetonitrile/ether mother liquor was saved and upon slow

evaporation produced purple-black crystals suitable for struc-

tural determination by X-ray methods (0.17 g, 19% yield).

UV–vis (CH₃CN) l_maxin nm (3 in mol^–1L cm^–1): 290

(1340), 320 (1370), 384 (1455), 580 (80). Anal. calcd for

(a) C₄₂H₄₉B₂F₈N₅Ni₂O₄S₄: C 45.56, H 4.46, N 6.33; found:

C 47.17, H 4.44, N 6.15.

For (b), H₂L3 (0.62 g, 1.6 mmol) dissolved in warm

(~40 °C) acetonitrile (40 mL) was mixed with nickel(II) tetra-

fluoroborate hexahydrate (0.57 g, 1.6 mmol) in warm

(~40 °C) methanol (20 mL) to give a brown-purple solution.

The solvent was allowed to evaporate to give a brown-purple

oily residue that was triturated in ether (5 mL) and then

rinsed with methanol (5 × 3 mL) until the wash solution was

colourless. The light brown powder was dried in air, dis-

solved in hot acetonitrile (90 mL) to give a brown-pink solu-

tion, concentrated to 20 mL on a rotary evaporator, and then

added dropwise with stirring to cold ether (200 mL) to pro-

duce a light-coloured precipitate. This was collected, washed

with ether (3 × 5 mL), and then dried in air to give a fine

powder (0.37 g, 41% yield). UV–vis (CH₃CN) l_maxin nm (3

in mol^–1L cm^–1): 290 (1300), 320 (1400), 385 (1390), 580

(65). Mass spectrum APCI(+) calcd for [NiHL3],

[C₂₀H₂₃N₂NiO₂S₂]⁺m/z: 445.0; found m/z: 445.0. Calcd for

[H₃L3], [C₂₀H₂₅N₂O₂S₂]⁺m/z: 389.1; found m/z: 389.1.

Calcd for [H₂L3-sal)], [C₁₃H₂₁N₂OS₂]⁺m/z: 285.1; found

m/z: 285.1. Anal. calcd for C₄₀H₅₂B₂F₈N₄Ni₂O₇S₄: C 42.89,

H 4.68, N 5.00; found: C 42.45, H 4.30, N 5.18.

[CoL3][OAc]·3H₂O (XVIII)

The procedure is the same as for XVII except that

chloroform was used to dissolve the product from trituration.

The final product is a brown-green powder (0.44 g, 47%

yield). UV–vis (CH₃CN) l_maxin nm (3 in mol^–1L cm^–1):

642 (106), 476 (135), 384 (650), 297 (3580), 265 (sh). Mass

spectrum

APCI(+)

calcd

for

[CoL3

+

H],

[C₂₀H₂₂CoN₂O₂S₂+ H]⁺m/z: 446.0; found m/z: 446.0.

Anal. calcd for C₂₂H₃₁CoN₂O₇S₂: C 47.31, H 5.59, N 5.02;

found: C 46.59, H 4.68, N 4.82.

[Co(L3)][BF₄] (XIX)

H₂L3 (1.5 g, 3.9 mmol) dissolved in warm (~40 °C)

chloroform (20 mL) was mixed with cobalt(II) tetrafluorobo-

rate hexahydrate (1.32 g, 3.9 mmol) in warm (~40 °C) aceto-

nitrile (30 mL) to produce a dark orange solution that quickly

deposited a black precipitate. This was collected and washed

with ice-cold acetonitrile (3 × 3 mL). When dry, the solid

was dissolved in hot (~60 °C) acetonitrile (30 mL) and the

solvent evaporated slowly in air to produce black crystals.

These were collected, washed with ice-cold acetonitrile (3 ×

3 mL), and then dried in air (1.34 g, 65% yield). UV–vis

(CH₃CN) l_maxin nm (3 in mol^–1L cm^–1): 252 (2900), 305

(3100), 390 (500), 475 (95), 683 (75). Mass spectrum APCI

(+) calcd for [CoL3 + H], [C₂₀H₂₂CoN₂O₂S₂+ H]⁺m/z:

446; found m/z: 446. Anal. calcd for C₂₀H₂₂BCoF₄N₂O₂S₂:

C 45.13, H 4.17, N 5.26; found: C 45.59, H 4.26, N 5.24.

[Co(L1-sal)][BF₄]₂(XVI)

H₂L1 (2.0 g, 4.5 mmol) dissolved in warm (~40 °C)

chloroform (15 mL) was mixed with cobalt(II) tetrafluorobo-

rate hexahydrate (1.5 g, 4.5 mmol) in warm (~40 °C) aceto-

nitrile (20 mL) to produce a deep black solution and a thick

black oily precipitate. This was collected by gravity filtration

and dissolved in chloroform from which black crystals were

obtained as the solvent slowly evaporated. These were col-

lected and washed with ice-cold acetonitrile (3 × 2 mL). The

crystals were redissolved in hot (~60 °C) acetonitrile (30 mL)

and the solution was left to evaporate slowly in air. When

nearly evaporated, the resulting black cubic crystals were col-

lected, washed with ice-cold acetonitrile (3 × 2 mL), and

then dried in air (0.56 g, 22% yield). UV–vis (CH₃CN) l_max

in nm (3 in mol^–1L cm^–1): 219 (2680), 243, (2550) 284

(3220), 388 (230), 474 (75), 637 (45). Mass spectrum APCI

(+) calcd for [Co(L1-sal)], [C₁₅H₂₃CoN₂OS₃]⁺m/z: 402.0;

found m/z: 402.0. Anal. calcd for C₁₅H₂₃B₂F₈CoN₂OS₃: C

31.27, H 4.02, N 4.86, Co 10.2; found: C 31.36, H 3.97, N

4.87, Co 10.1.

[Co(L3-sal)(CH₃OH)][BF₄]₂·CH₃OH (XX)

H₂L3 (88 mg, 0.23 mmol) dissolved in acetonitrile

(20 mL) was mixed with cobalt(II) tetrafluoroborate hexahy-

drate (134 mg, 0.393 mmol) in methanol (30 mL) to produce

a light orange solution that quickly deposited a brown

precipitate. The precipitate was collected and discarded.

Solvent was allowed to evaporate slowly from the filtrate to

produce black crystals that were collected, recrystallized

from methanol, washed with ice-cold acetonitrile (1 mL),

and then dried in air (84 mg, 63% yield). Anal. calcd for

C₁₅H₂₇B₂CoF₈N₂O₃S₂: C 31.06, H 4.69, N 4.83; found: C

31.37, H 4.05, N 4.85.

Published by NRC Research Press

Lucas et al.

1179

Table 1. Crystallographic data for [Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III) and

[Ni(HL3)]₂[BF₄]₂·CH₃CN (XIV).

Compound

Parameter

III

XIV

Empirical formula

Formula mass

Crystal colour, habit

Crystal dimensions, mm

Crystal system

Space group

Z

C₆₈H₈₈N₆Ni₃O₁₇S₆

1629.93

Green, prism

0.40×0.30×0.15

Monoclinic

C2/c (No. 15)

4

C₄₂H₄₉B₂F₈N₅Ni₂O₄S₄

1107.13

blue/purple, prism

0.35×0.35×0.40

Triclinic

P-1 (No. 2)

2

a (Å)

b (Å)

c (Å)

33.472(10)

15.931(4)

14.992(4)

90, 116.159(6), 90

7176(3)

1.509

153 1

10.26

0.71069

3416

61.4

13.568(5)

16.166(4)

11.757(2)

100.25(2), 104.41(2), 81.73(2)

2444(1)

1.504

299

10.17

0.71069

1140

a, b, g (°)

V (Å³)

D_calcd(g/cm³)

T (K)

µ (cm^–1)

l

F(0,0,0) (electrons)

2q (max.) (°)

No. reflections measured

No. unique reflections

No. variable parameters

R1 (I > 2.00s(I))^a

wR2 (all refl.)^b

Last D-map

55.2

15912

7258

472

0.0931

10126

611

0.0608

0.1953

0.2584

Highest peak (e^–/Å³)

Deepest hole (e^–/Å³)

2.62

–0.95

1.45

–0.76

Note: Throughout this work, esds are in parentheses and refer to the last digit printed.

^aR1 = S∣F_o∣ – ∣F_c∣/S∣F_o∣.

^bwR2 = [S(w(F_o– F_c²)²/Sw(F_o)²]^1/2

.

2

X-ray studies

Results and discussion

A summary of crystallographic data is in Tables 1 and 2.

Figures 2–5 show views of the structure and numbering

schemes for III, XIV, XVI, and XIX, respectively. In all

cases, non-hydrogen atoms were refined anisotropically. For

III, atoms O8 and O9 are disordered lattice solvent water.

They make up one full water molecule and were refined

with the sum of their occupancies equal to one. The H atoms

for the lattice solvent water molecules O8, O9, and O10

could not be located in difference map positions and were

therefore omitted from the model. They were included in the

formula for the calculation of intensive properties. Hydrogen

atoms H5a and H7a were introduced in difference map posi-

tions. Both were refined with distance restraints and H7a was

also refined with an angle restraint. All other hydrogen atoms

were introduced in calculated positions and refined on a rid-

ing model.

For XIV, hydrogen atoms H1o and H3o were introduced

in difference map positions. All other hydrogen atoms were

introduced in calculated positions and refined on a riding

model. Angle restraints were applied to both tetrafluoroborate

anions. For XVI and XIX, hydrogen atoms were introduced

in calculated positions and refined on a riding model. De-

scriptions of the experimental procedures, anisotropic thermal

parameters, and a full listing of bond lengths and angles are

available as Supplementary data.

Although a two-step synthesis for H₂L3 was reported in

1950 by Lions and Dwyer,¹⁵the syntheses reported herein

are each one-pot processes. All three ligands, under mild

conditions in the presence of a metal atom, lose one salicylal-

dehyde, for example, during formation of [Co(L1-sal)][BF₄]₂

(XVI) and [Co(L3-sal)(CH₃OH)][BF₄]₂·CH₃OH (XX). This

appears to be simple hydrolysis via nucleophilic attack by ad-

ventitious water on the carbon atom of a metal-bound imine

producing a primary amine bound to the metal and liberating

salicyladehyde. A question this raises is why only one end of

the chain hydrolyzes. Models suggest it is due to differences

in accessibility of the site for attack. In the early stages of

complexation, if only one imine nitrogen is bound to the

metal, approach by a water molecule is comparatively unim-

peded. However, when all coordination sites on the metal have

been filled by a ligand, the remaining imino-carbon atom is

shielded from nucleophilic attack both above and below the

plane defined by the bent M–C=N system. Shielding of the

imine system arises from sulfur nonbonding electron density on

one side of the plane and from oxygen nonbonding electron

density on the other. Support for this explanation is obtained

from the observation that syntheses of hydrolyzed and unhydro-

lyzed materials sometimes occur together and must be separated

during workup. Preparations for [Ni(HL3-sal)Br]Br·CH₃OH

(X) and [Ni(HL3)Br]·2H₂O (XI) illustrate this point.

Published by NRC Research Press

1180

Can. J. Chem. Vol. 89, 2011

Table 2. Crystallographic data for [Co(L1-sal)][BF₄]₂(XVI) and [Co(L3)][BF₄] (XIX).

Compound

Parameter

XVI

XIX

Empirical formula

Formula mass

Crystal colour, habit

Crystal dimensions, mm

Crystal system

Space group

Z

C₁₅H₂₃B₂CoF₈N₂OS₃

576.08

C₂₀H₂₂BCoF₄N₂O₂S₂

532.26

Dark red, prism

0.25×0.20×0.45

Monoclinic

P2₁/n (No. 14)

4

red-black, block

0.25×0.25×0.45

Orthorhombic

Pna2₁(No. 33)

8

a (Å)

b (Å)

c (Å)

9.087(2)

13.972(3)

18.055(3)

90, 100.02(2), 90

2257.4(9)

1.695

33.773(4)

11.183(7)

11.397(4)

90, 90, 90

4304.4(30)

1.643

a, b, g (°)

V (Å³)

D_calcd(g/cm³)

T (K)

299

11.15

299

10.47

µ (cm^–1)

l

0.71069

1168

55.1

5222

290

0.71069

2176

55.1

5193

578

F(0,0,0) (electrons)

2q (max.) (°)

No. reflections measured

No. variable parameters

R1 (I > 2.00s(I))^a

wR2 (all refl.)^b

Last D-map

0.0438

0.1207

0.0459

0.1282

Highest peak (e^–/Å³)

Deepest hole (e^–/Å³)

0.70

–0.46

0.65

–0.50

Note: Throughout this work, esds are in parentheses and refer to the last digit printed.

^aR1 = S∣F_o∣ - ∣F_c∣/S∣F_o∣.

^bwR2 = [S(w(F_o- F_c²)²)/Sw(F_o)²]^1/2

.

2

A further feature of these systems is the occurrence of

complexes in which the phenolic oxygens of the ligands may

or may not be deprotonated. These occurrences are likely

controlled, at least in part, by solubility effects with less solu-

ble species being more readily deposited as precipitates of com-

plex. The simultaneous preparations of {[Ni(HL3-sal)Br]Br}

[Ni(L3-sal)Br]·2CH₃OH (IX), [Ni(HL3-sal)Br]Br·CH₃OH (X),

and [Ni(HL3)Br]·2H₂O (XI) in one synthetic batch illustrate

this effect. Protonated phenolic oxygens coordinated to met-

als have been observed previously in salicylaldimine com-

plexes,¹⁶although precipitation of both protonated and

deprotonated forms when complexation is carried out in the

absence of added base is less common.

complete coordination spheres for the two distinct nickel

complexes can be viewed. Pertinent bond lengths and angles

are in Table 3.

Structural evidence for hydrogen bonding is, as usual,

bond lengths and angles. Thus, the carboxylic oxygen (O(7))

and attached hydrogen (H(7a)) are 0.969(19) Å from each

other, whereas phenolic oxygen (O(3)) lies 1.566(19) Å from

H(7a). Both distances are consistent with hydrogen bonding²⁸

as is the angle O(3)–H(7a)–O(7) (177(1)°). Likewise, O(5)

and H(5a) lie at 0.974(19) Å from each other, whereas O(2)

lies 1.503(19) Å from H(5a) and angle O(5)–H(5a)–O(2)

is 169.6(5)°. Nickel–oxygen bond distances are comparable

to those in [Ni₂(Hhsae)₂(OAc)₂(CH₃OH)₂] (H₂hsae = 2-(5-

hydroxysalicylideneamino)ethanol)¹⁸(2.0160(9)–2.1442(10) Å)

or {[Ni₂(trans-tachH)₂(OAc)₄(H₂O)](OAc)₂·5H₂O}_n(tach =

cis,trans-1,3,5-triaminocyclohexane)¹⁹(2.061(2)–2.143(2) Å).

The Ni–N lengths in III are comparable to those in [Ni₂(Hhsae)₂

(OAc)₂(CH₃OH)₂] (1.9987(11) Å) and 2-(diisopropyl)-

phosphinobenzyl-N,N-dimethylaminenickel(II) dibromide²⁰

(2.042(2) Å) and the Ni–S bonds compare well to those of

[Ni(PTHD(H₂O)]²⁺(PTHD = 3,6,9,12,15-pentathiaheptadecane)¹⁰

(2.403(2)–2.425(2) Å) or [Ni(TCS)₂][ClO₄]₂(TCS = 1-methoxy-

10-methyl-12-thia-2,9-diaza-tricyclo[8.3.1.0^3,8]tetradeca-3,5,7-

triene)²¹(2.4055(11) Å).

Simple complexes of both Ni(II) and Cu(II)¹⁴can be

formed from H₂L1, H₂L2, and H₂L3, but analogous com-

plexes of Co(II) were not obtained under aerobic conditions.

This is not surprising given the propensity of complexed Co

(II), especially in presence of nitrogen donors, to oxidize to

Co(III).¹⁷

X-ray studies

[Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III) consists, per

formula unit, of three similar complex molecules, four acetic

acid molecules hydrogen bonded to the metal complexes and

three molecules of lattice water, one of which is disordered.

The crystallographic asymmetric unit of this substance is

half its formula unit and, for discussion purposes, Fig. 2

presents a partial expansion of the asymmetric unit so that

TheO–Ni–Nangles are comparable to those inNi(IMBF)₂(CH OH)

3

2

(IMBF = 4-(1-bromo-3,3,3-trifluoro-2-oxopropylidene)-2,2,5,5-

tetramethyl-3-imidazolene-1-oxyl)²²(84.7(2)° and 88.4(1)°)

23

or those in Ni[(C₂H₅O)₂PSNHNCPh(o-O)OCH₃]₂(87.69(13)°

Published by NRC Research Press

Lucas et al.

1181

Fig. 2. ORTEP of [Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III) (see text). Thermal ellipsoids are at the 50% probability level. H₂Os are

omitted for clarity.

and 92.31(14)°). The O–Ni–O and N–Ni–N angles are close

to 90° and 180°, respectively, whereas the O–Ni–S angles

are of two types representing cis- and trans-donors. The cis

angles differ very little from 90°, whereas the three distinct

trans-angles remain closer to 180° than those, for example,

of 168.32(6)° in [NiCl(H₂O)₂(thpd)]Cl (thpd = 1-(3-thia-5-

hydroxypentyl)-3,5-dimethylpyrazole).²⁴The six N–Ni–S an-

gles, four on Ni(1) and two on Ni(2), all show deviations

observed in III and related compounds (vide supra). Hydro-

gen bonds between halves of the dimeric cation have angles

O(1)–H(1o)···O(4) = 173(2)° and O(3)–H(3o)···O(2) = 170(2)°.

Distances O(1)–H(1o)···O(4) and O(3)–H(3o)···O(2) are both

2.44(3) Å and distances H(1o)···O(4) and H(3o)···O(2) are both

1.49(4) Å. These may be compared with literature values

for strong hydrogen bonds of 2.70 Å for O–H···O and

1.70 Å for H···O.²⁸

from 90° on both Ni(1) and Ni(2) of 5°

1° that are sim-

Eight O–Ni–N angles occur in the two monomers and are

comparable to those in III and related species (vide supra).

There are four N–Ni–S angles in each of the monomers with

deviations between 6.9° and 8.6° from 90°. The largest is

1.1° (~14%) greater than deviations observed by Ladd et

al.²⁵and 2.4° (~38%) greater than the largest observed for

comparable angles in III. There are no obvious intramolecu-

lar reasons why deviations should be larger in XIV than in

III. There are, however, three contacts in XIV that are less

than the sum of the van der Waals’ radii of the atoms in-

volved. These are N(5)···H(10a) (2.6 1 Å), S(1)···H(28a_i)

(3.1 1 Å) and S(1)···H(29b_i) (3.1 1 Å) that “lift” S(1)

causing an increase in the S(1)–Ni(1)–N(2) angle. The sum of

the van der Waals’ radii in each case is 3.00, 3.25, and 3.25 Å.²⁹

As with III, bond angles in XIV fall into two categories.

There are those that lie close to ideal values for a regular oc-

tahedron and those that show significant deviation and, as

with III, the latter category all involve a sulfur atom. This

may not be coincidental in view of observations^13,30,31that

ilar to those observed in [Ni(aptp)(en)][NO₃]₂(aptp = 1-[[2-

[2-aminoethyl)imino]propyl]thio]-2-propanone).²⁵Finally, there

are two distinct S–Ni–S angles, one at Ni(1) and one at Ni(2).

Both are comparable to those in [Ni(PDH)(CH₃CN)₂][ClO₄]₂

(PDH = 1,6-bis(2-pyridyl)-2,5-dithiahexane)²⁶(S–Ni–S =

83.2(2)° and 83.2(2)°) or [Ni(18S₄O₂][BF₄]₂(18S₄O₂

1,10-dioxa-4,7,13,16-tetrathiacyclooctadecane)²⁷(S–NiS

94.52(13)°, 91.56(12)°, 88.12(12)°, and 88.37(13)°).

=

[Ni(HL3)]₂[BF₄]₂·CH₃CN (XIV) has in its unit cell a pair

of similar but nonidentical hydrogen-bonded unipositive

complex cations, two tetrafluoroborate anions, and one mole-

cule of lattice acetonitrile. The ligand coordinates by both

protonated and deprotonated phenolic oxygens, and dimers

of cations are formed by hydrogen bonds involving phenolic

hydrogens that were detected and refined in the crystal struc-

ture study. Pertinent bond lengths and angles are in Table 4.

The four Ni–O, four Ni–N, and four Ni–S bonds in the

dimeric cation of XIV have lengths similar to those

Published by NRC Research Press

1182

Can. J. Chem. Vol. 89, 2011

–

Fig. 3. ORTEP of [Ni(HL3)]₂[BF₄]₂·CH₃CN (XIV). Thermal ellipsoids are at the 50% probability level. BF₄ions and CH₃CN are omitted for

clarity.

sulfur, relative to donors such as nitrogen or oxygen, is for-

giving about its bond lengths and angles in a way that has

been described as its bonding “plasticity”. Thus, strain in

complex systems is more likely to be accommodated at sulfur

than at nitrogen or oxygen donors.

Fig. 4. ORTEP of [Co(L1-sal)][BF₄]₂(XVI). Thermal ellipsoids are

shown at the 50% probability level.

The structure of [Co(L1-sal)][BF₄]₂(XVI) (Fig. 4) consists

of an N₂OS₃coordination sphere with the three sulfurs

arranged facially. Pertinent bond lengths and angles are in

Table 5.

The Co–O bond length in XVI is comparable to those in

Co(III) cations such as [Co(3-Cl-acacen)(NH₃)₂][BPh₄]³²

(3-Cl-acacen = 3-chloro-bis(acetylacetone)ethylenediimine)

(1.881(4) Å) and [Co(L)(phen)N₃]³³(where H₂L = 2-hydroxy-

acetophenone-N(4)-phenylsemicarbazone and phen = 1,10-

phenanthroline) (1.866(4) and 1.914(3) Å). The Co–N dis-

tances compare well to those (1.8918(9), 1.951(6), and

1.960(6) Å) in [Co(3-Cl-acacen)(NH₃)₂][BPh₄], where the

shorter is to imino-nitrogen, or in [Co(L)(phen)N₃] (1.865(4)

(azomethine), 1.961(4) and 1.968(5) (phen), and 1.926(4) Å

(azide)). The Co–S lengths are comparable to those in

[Co(L⁴)(bipy)(N₃)]³⁴(H₂L⁴= 2-hydroxy-acetophenone-N(4)-

phenylthiosemicarbazone and bipy

=

2,2′-bipyridine)

(2.2126(7) Å (mercaptide)) and in [Co(tsaltp)]₂Cl₂(H₂tsaltp =

N,N′-bis(thiosalicylideneimine)-2,2′-thiobis(ethylamine))³⁵

(2.277(3) Å (thioether) and 2.218(3) and 2.278(3) Å (bridg-

ing mercaptide)).

The unit cell for [Co(L3)][BF₄] (XIX) (Fig. 5) contains

two similar but nonidentical [Co(L3)][BF₄] units. Each of

Published by NRC Research Press

Lucas et al.

1183

Fig. 5. ORTEP of [Co(L3)][BF₄] (XIX). Thermal ellipsoids are shown at the 50% probability level.

Table 3. Selected bond lengths and angles in

[Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III).

the cations consists of an N₂O₂S₂coordination sphere with

the nitrogens in a trans arrangement. Pertinent bond lengths

and angles are in Table 6. The Co–S, Co–O, and Co–N

bond lengths in both cations are similar to those in XVI and

related species (vide supra).

Bond length (Å)

Ni(1) cation

Ni–O(2)

Bond angle (°)

2.026(4)

2.021(3)

2.028(4)

2.032(4)

2.441(2)

2.459(2)

O(2)–Ni(1)–N(1)

O(2)–Ni(1)–O(1)

N(1)–Ni(1)–O(1)

O(2)–Ni(1)–N(2)

N(1)–Ni(1)–N(2)

O(1)–Ni(1)–N(2)

O(2)–Ni(1)–S(2)

N(1)–Ni(1)–S(2)

O(1)–Ni(1)–S(2)

N(2)–Ni(1)–S(2)

O(2)–Ni(1)–S(1)

N(1)–Ni(1)–S(1)

O(1)–Ni(1)–S(1)

N(2)–Ni(1)–S(1)

S(2)–Ni(1)–S(1)

92.79(17)

91.34(17)

86.76(17)

86.32(17)

179.0(2)

93.80(17)

170.39(9)

96.26(14)

92.41(13)

84.61(14)

91.74(12)

83.98(14)

170.4(1)

Ni–N(1)

Spectroscopic studies

Ni–O(1)

Electronic spectra of the ligands H₂L1 and H₂L3 were col-

lected in methanol and in acetonitrile and there are no signif-

icant qualitative differences in the overall appearances of the

spectra with solvent. Both ligands display absorptions at

~225, ~255, and ~314 nm that can be assigned to two

p→p* transitions of the aromatic system,^36–39and to a

p→p* transition of the –C=N– system^37,23. In addition, a

weak absorption of unknown origin occurs at ~400 nm in

the spectra of both H₂L1 and H₂L3.

All complexes in this study can be generalized into three

related coordination sphere types. As a visual assistance to

the following discussion these are presented in Fig. 6.

The IR spectrum of XIV in the region 3700–3000 cm^–1is

consistent with its X-ray structure and shows a band attribut-

able to O–H stretching that is shifted to 3250 cm^–1and

broadened when compared with the corresponding band at

3450 cm^–1in the spectrum of the free ligand. The shift and

broadening is expected for a hydrogen-bonded system.⁴⁰The

electronic spectrum of this compound is consistent with its

solid-state structure, which suggests the coordination sphere

of the nickel atoms is retained, at least in a general sense, in

solution. The spectrum (Table 7) consists of bands at 290,

320, 384, and 580 nm. The first and second of these correlate

with bands at 258 and 313 nm in the spectrum of the free

ligand and both are shifted to longer wavelength in the com-

plex.

Ni–N(2)

Ni–S(2)

Ni–S(1)

95.5(1)

86.00(5)

Ni(2) cation

Ni–O(3)

2.030(4)

2.030(3)

2.419(2)

O(3)–Ni(2)–O(3_2)

O(3)–Ni(2)–N(3_2)

O(3)–Ni(2)–N(3)

O(3_2)–Ni(2)–N(3_2)

O(3_2)–Ni(2)–N(3)

O(3)–Ni(2)–S(3)

91.87(17)

92.17(16)

86.97(16)

92.17(16)

171.38(9)

90.96(12)

171.38(9)

178.8(2)

Ni–O(3_2)

Ni–N(3)

Ni–N(3_2)

Ni–S(3)

Ni–S(3_2)

O(3)–Ni(2)–S(3_2)

O(3_2)–Ni(2)–S(3)

O(3_2)–Ni(2)–S(3_2)

N(3)–Ni(2)–N(3_2)

N(3)–Ni(2)–S(3)

N(3)–Ni(2)–S(3_2)

N(3_2)–Ni(2)–S(3)

N(3_2)–Ni(2)–S(3_2)

S(3)–Ni(2)–S(3_2)

84.8(1)

96.11(14)

84.79(14)

87.42(6)

All spectra of the nickel complexes (Table 7) consist of

three intense bands (3 ∼ 10³mol^–1L cm^–1) and one much

weaker band (3 ∼ 10¹mol^–1L cm^–1). The former are fre-

quently asymmetrical and display shoulders on either or both

Published by NRC Research Press

1184

Can. J. Chem. Vol. 89, 2011

Table 4. Selected bond lengths and angles in

[Ni(HL3)]₂[BF₄]₂·CH₃CN (XIV).

Table 5. Selected bond lengths and angles in [Co(L1-sal)][BF₄]₂

(XVI).

Bond length (Å)

Ni(1) cation

Ni–S(1)

Bond angle (°)

Bond lengths (Å)

Bond angles (°)

O(1)–Co–N(1)

O(1)–Co–N(2)

O(1)–Co–S(3)

O(1)–Co–S(2)

O(1)–Co–S(1)

N(1)–Co–N(2)

N(1)–Co–S(3)

N(1)–Co–S(2)

N(1)–Co–S(1)

N(2)–Co–S(3)

N(2)–Co–S(2)

N(2)–Co–S(1)

S(3)–Co–S(1)

S(3)–Co–S(2)

S(1)–Co–S(2)

Co–S(1)

Co–S(2)

Co–S(3)

Co–O(1)

Co–N(1)

Co–N(2)

2.235(1)

92.8(1)

85.7(1)

89.60(6)

87.52(7)

179.32(7)

92.6(1)

177.24(8)

92.88(7)

87.35(8)

86.23(7)

171.45(8)

95.00(8)

90.27(3)

88.59(3)

91.81(3)

2.4495(12)

2.4497(13)

2.077(3)

2.033(2)

2.025(3)

2.024(3)

1.426(5)

0.946(5)

S(1)–Ni–S(2)

S(1)–Ni–O(1)

S(1)–Ni–O(2)

S(1)–Ni–N(1)

S(1)–Ni–N(2)

S(2)–Ni–O(1)

S(2)–Ni–O(2)

S(2)–Ni–N(1)

S(2)–Ni–N(2)

O(1)–Ni–O(2)

O(1)–Ni–N(1)

O(1)–Ni–N(2)

O(2)–Ni–N(1)

O(2)–Ni–N(2)

N(1)–Ni–N(2)

O(1)–H(48)···O(4)

87.10(4)

168.55(10)

91.26(9)

83.12(11)

98.63(12)

91.88(9)

169.95(10)

96.24(10)

83.06(10)

91.67(12)

85.66(14)

92.56(15)

93.41(13)

87.39(13)

178.07(16)

164.53(3)

2.2393(9)

2.2337(8)

1.901(2)

1.909(2)

1.983(2)

Ni–S(2)

Ni–O(1)

Ni–O(2)

Ni–N(1)

Ni–N(2)

H(49)···O(2)

O(1)–H(48)

Table 6. Selected bond lengths and angles in [Co(L3)][BF₄] (XIX).

Ni(2) cation

Ni–S(3)

2.4391(11)

2.4790(13)

2.069(2)

2.049(2)

2.020(4)

2.015(4)

1.017(5)

1.515(5)

S(3)–Ni–S(4)

S(3)–Ni–O(3)

S(3)–Ni–O(4)

S(3)–Ni–N(3)

S(3)–Ni–N(4)

S(4)–Ni–O(3)

S(4)–Ni–O(4)

S(4)–Ni–N(3)

S(4)–Ni–N(4)

O(3)–Ni–O(4)

O(3)–Ni–N(3)

O(3)–Ni–N(4)

O(4)–Ni–N(3)

O(4)–Ni–N(4)

N(3)–Ni–N(4)

O(3)–H(49)···O(2)

86.55(6)

171.2(1)

91.9(1)

84.4(1)

97.7(1)

91.1(1)

171.4(1)

97.9(1)

83.85(10)

91.60(11)

87.46(14)

90.55(13)

90.43(14)

87.90(14)

177.36(14)

177.13(3)

Bond lengths (Å)

Co(1) cation

Co(1)–S(1)

Bond angles (°)

Ni–S(4)

Ni–O(3)

2.204(2)

2.224(2)

1.932(4)

1.894(4)

1.938(5)

1.922(4)

S(1)–Co(1)–S(2)

S(1)–Co(1)–O(1)

S(1)–Co(1)–O(2)

S(1)–Co(1)–N(1)

S(1)–Co(1)–N(2)

S(2)–Co(1)–O(1)

S(2)–Co(1)–O(2)

S(2)–Co(1)–N(1)

S(2)–Co(1)–N(2)

O(1)–Co(1)–O(2)

O(1)–Co(1)–N(1)

O(1)–Co(1)–N(2)

O(2)–Co(1)–N(1)

O(2)–Co(1)–N(2)

N(1)–Co(1)–N(2)

92.76(7)

176.7(2)

87.94(19)

89.0(2)

93.5(2)

86.7(2)

176.8(2)

91.4(2)

89.0(2)

92.8(2)

94.3(2)

83.3(2)

85.5(2)

94.1(2)

177.5(2)

Ni–O(4)

Co(1)–S(2)

Ni–N(3)

Co(1)–O(1)

Co(1)–O(2)

Co(1)–N(1)

Co(1)–N(2)

Ni–N(4)

O(3)–H(49)

H(48)···O(4)

sides. These indicate the presence of unresolved bands that

have been deconvoluted and identified by Bosnich and co-

workers^37,41as arising from either metal-to-ligand charge

transfer (MLCT), intraligand p→p* CT (charge transfer), or,

at wavelengths >350 nm, from d–d processes. Unfortunately,

the coordination number and geometry of the complexes can-

not be determined from their electronic spectra because of

overlapping absorptions.

For III, the IR spectrum of its free ligand exhibits a band

at 3450 cm^–1attributable to stretching of the phenolic O–H

bonds, whereas the complex exhibits no band in this region

but rather a broad absorption centred at 3150 cm^–1attribut-

able to stretching vibrations of the hydrogen-bonded carbox-

ylic O–H functions and perhaps also those of the lattice water

molecules. The electronic spectrum of III is very similar to

that of XIV with the exception of a high-energy shoulder on

the band at ~384 nm in the spectrum of III that is not appa-

rent in that of XIV. As discussed previously, the band at

~384 nm is an envelope of unresolved bands and in III this

is evident from its partial resolution.

Co(2) cation

Co(2)–S(3)

Co(2)–S(4)

Co(2)–O(3)

Co(2)–O(4)

Co(2)–N(3)

Co(2)–N(4)

2.202(2)

2.222(2)

1.924(4)

1.902(4)

1.885(5)

1.944(5)

S(3)–Co(2)–S(4)

S(3)–Co(2)–O(3)

S(3)–Co(2)–O(4)

S(3)–Co(2)–N(3)

S(3)–Co(2)–N(4)

S(4)–Co(2)–O(3)

S(4)–Co(2)–O(4)

S(4)–Co(2)–N(3)

S(4)–Co(2)–N(4)

O(3)–Co(2)–O(4)

O(3)–Co(2)–N(3)

O(3)–Co(2)–N(4)

O(4)–Co(2)–N(3)

O(4)–Co(2)–N(4)

N(3)–Co(2)–N(4)

92.98(7)

174.4(2)

87.6(1)

90.1(2)

92.3(2)

89.0(2)

179.1(1)

91.5(2)

88.2(2)

90.5(2)

95.2(2)

82.5(2)

87.8(2)

92.4(2)

177.6(2)

known structures of cobalt, copper,¹⁴and nickel species dis-

cussed so far plus analytical and spectroscopic evidence.

Thus, the structures proposed for [Ni(HL1)]₂[BF₄]₂·5H₂O (XII),

[Ni(HL2)]₂[BF₄]₂·3H₂O (XIII), and [Ni(HL3)]₂[BF₄]₂·3H₂O

(XV) are similar to that observed by X-ray methods for XIV

The structures proposed for the remaining 13 nickel com-

plexes in this study are based upon extrapolations from the

Published by NRC Research Press

Lucas et al.

1185

Fig. 6. Coordination sphere types. Those in italics were determined by X-ray methods.

Table 7. Electronic spectroscopy of nickel complexes.

Electronic spectra and band assignments^a

Ligand p→p*

Compound

(phenolic)

290 (1340)

290 (1354)

Ligand p→p* (C=N)

320 (1370)

Ni→N MLCT

384 (1455)

383 (1450)

d–d

580 (80)

577 (41)

[Ni(HL3)]₂[BF₄]₂·CH₃CN (XIV)

[Ni(L3)·HOAc]₂[Ni (L3)·2HOA-

c]·3H₂O (III)

345 (sh)

[Ni(HL2)][OAc] (II)

[Ni(HL3)]₂[BF₄]₂·3H₂O (XV)

[Ni(L1)].H₂O (I)

[Ni(HL1-sal)]Cl₂·H₂O (IV)

[Ni(HL2-sal)]Cl₂·CH₃OH (V)

{[Ni(HL3-sal)Br]Br}[Ni(L3-sal)

Br]·2CH₃OH (IX)

280 (sh)

308 (1450)

320 (1400)

310 (1500)

323 (1500)

320 (1400)

319

340 (sh)

400 (1500)

385 (1390)

408 (1400)

370 (1400)

380 (1100)

380

610 (54)

580 (65)

610 (55)

602 (40)

595 (45)

290 (1300)

280 (1350)

293 (1500)

287 (1300)

285

406 (sh)

[Ni(HL2)]₂[BF₄]₂·3H₂O (XIII)

[Ni(HL1)]₂[BF₄]₂·5H₂O (XII)

283 (sh)

320 (1527)

320 (1485)

340 (sh)

378 (1431)

380 (1207)

410 (sh)

420 (sh)

600 (50)

620 (25)

Note: MCLT, metal-to-ligand charge transfer.

^aIn CH₃CN. d in nm (ɛ in mol^–1L cm^–1).

except that the ethereal oxygen and thioether sulfur in the

midpoints of L2 and L1, respectively, are not expected to be

coordinated to their nickel atoms and the solvation in their

crystals is water instead of acetonitrile. Thus, in all cases, the

coordination sphere should be N₂O₂S₂with trans-nitrogens

and cis-sulfurs and -oxygens. It is anticipated that all will be

hydrogen-bonded dimers and the analytical results are consis-

tent with such formulations. There are only relatively minor

differences in the various values of l_maxamong these com-

pounds, suggesting that a common coordination environment

exists in all four cases. Finally, the IR spectra of all four

compounds are similar in the region between 3000 and

3800 cm^–1where evidence of hydrogen bonding can be seen

as described previously.

The structure proposed for [Ni(L1)]·H₂O (I) is similar to

that observed by X-ray for [Co(L3)][BF₄] (XIX) except that

the centre sulfur of L1 is not expected to be bound to nickel.

The coordination sphere is therefore N₂O₂S₂with trans-nitrogens

and cis-sulfurs and -oxygens. The overall appearance of the

electronic spectrum of I is similar to that of the other

nickel compounds, although the value of l_maxfor the band

envelope near 385 nm in the other compounds is shifted to

408 nm in I. This amount of shift is consistent with varia-

tions owing to changes in bond angles inside the coordina-

tion sphere in related metal complexes^11,27and may be

arising from a different “fit” of the nickel atom with this

ligand compared with the others. In support, it may be

noted (Table 7) that II with a ligand of similar dimensions

displays a similar shift of l_max

.

The formulation [Ni(HL2)][OAc] for II is consistent with

analytical data and its infrared spectrum which shows the

usual evidence of hydrogen bonding between a phenolic hy-

drogen and an uncoordinated acetate ion. Uncoordinated ace-

tate is supported by the infrared spectrum’s strong peaks at

1592 and 1445 cm^–1from v_C=Oof uncoordinated acetate that

occur typically near 1580 and 1425 cm^–1.⁴²

The structures of [Ni(HL1-sal)]Cl₂·H₂O (IV), [Ni(HL2-

sal)]Cl₂·CH₃OH (V), and [Ni(L3-sal)Cl]·H₂O (VI) are pro-

posed to have N₂OS₃, N₂O₂S₂and N₂OS₂Cl donor sets,

respectively. In the case of IV, a facial arrangement of

sulfurs similar to that observed in [Co(L1-sal)][BF₄]₂,

[Ni(PTTN)(H₂O)][ClO₄]₂·CH₃OH (PTTN = 1,9-bis(2-pyridyl)-

2,5,8-trithianonane)²⁶and [Ni(PTTD)][ClO₄]₂(PTTD

=

1,12-bis(2-pyridyl)-2,5,8,11-tetrathiadecane)²⁶is anticipated

and consistent with the compound’s spectroscopic proper-

ties. Specifically, [Ni(PTTN)(H₂O)][ClO₄]₂·CH₃OH, which

also has an N₂OS₃coordination sphere, exhibits inter alia a

d–d band at 545 nm that correlates with the 602 nm band

in IV, the shift between the two arising from differences

between the kinds of oxygen and nitrogen donors in the

two compounds.²⁶The IR, spectrum of IV shows a broad

band at 3450 cm^–1that is unshifted and of similar shape to

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Can. J. Chem. Vol. 89, 2011

Table 8. Electronic spectroscopy of cobalt complexes.

Electronic spectra and band assisgnments^a

Ligand p–p*

(phenolic)

Compound

Ligand p–p* (C=N)

MLCT

d–d

[Co(L1-sal)][BF₄]₂(XVI)

[Co(L2)][OAc]·3H₂O (XVII)

[Co(L3)][OAc]·3H₂O (XVIII)

[Co(L3)][BF₄] (XIX)

285 (sh)

290 (sh)

289 (1240)

290 (sh)

308 (1750)

310 (1800)

320 (sh)

363 (sh)

340 (sh)

370 (sh)

389 (1560)

380 (1760)

390 (1100)

392 (1690)

493 (125)

484 (105)

488 (85)

715 (42)

680 (35)

660 (65)

680 (83)

308 (1890)

480 (112)

Note: MLCT, metal-to-ligand charge transfer.

^aIn CH₃CN. l in nm (ɛ in mol^–1L cm^–1).

that of the free ligand suggesting no hydrogen bonding by

the phenolic OH group or the molecule of water. This ar-

gues for a monomeric formulation rather than a hydrogen-

bonded dimer.

For V, the most probable arrangement of the N₂O₂S₂do-

nors is similar to the arrangement in IV except that the mid-

dle donor in the ligand’s aliphatic chain is now an ethereal

oxygen so that the complex’s two oxygen donors adopt a cis

relationship. Electronic spectra of the two compounds are, as

a result, similar, although the intense band at 370 nm in IV is

shifted to 380 nm in V obscuring the shoulder at 406 nm in

IV. At the same time, the shortest wavelength d–d band at

602 nm in IV is shifted to 595 nm in V, placing it very close

to a similar band at 596 nm in [Ni(DTTCE)][ClO₄]₂

III plus identification by various techniques of the same or

analogous cations in other species in this study. In addition,

the mass spectrum of this compound exhibits a cluster of

peaks from m/z 400 to 403, the most intense of which is at

m/z 401 corresponding to [C₁₅H₂₃N₂NiOS₃]⁺or [Ni(L1-sal)]⁺.

Thus, a pair of cations having N₂OS₃coordination spheres

with facially disposed sulfurs is anticipated. One of these

should have an intact phenol OH coordinated to nickel,

whereas the other should have a deprotonated phenoxy oxy-

gen in the analogous coordination site. The compound’s IR

spectrum shows a broad band at 3450 cm^–1, suggesting the

absence of hydrogen bonding by either the phenolic group

or water. Likewise, from ligand L2, which is like L1, a sim-

ilar structure, {[Ni(HL2-sal)]Br₂}₂{[Ni(L2-sal)]Br}·2CH₃OH

(VIII), is proposed. Agreement of this formulation with the

compound’s analysis is good and its mass spectrum has a

peak at m/z 385.0 corresponding to [C₁₅H₂₃N₂NiO₂S₂]⁺or

[Ni(L2-sal)]⁺. The compound’s IR spectrum shows a broad

band at 3450 cm^–1, suggesting the absence of hydrogen

bonding by either phenolic groups or methanol. Finally, for

{[Ni(HL3-sal)Br]Br}[Ni(L3-sal)Br]·2CH₃OH (IX), the pro-

posed structure involves one [Ni(HL3-sal)Br]⁺, as in X,

one [Ni(L3-sal)Br]⁺as in VI, one ionic bromide, and two

molecules of methanol of solvation. This agrees well with

the analytical data and the mass spectrum exhibits a peak at

m/z 341.0 consistent with [C₁₃H₁₉N₂NiOS₂]⁺or [Ni(L3-sal)]⁺.

As noted previously in this series, the IR spectrum of IX

shows a broad band at 3450 cm^–1, suggesting the absence of

hydrogen bonding by either phenolic groups or methanol.

The electronic spectra of XIX and XVI are similar consist-

ing of three intense and two less intense bands. The two

higher energy intense bands can be related to similar bands

in the free ligand as indicated in Table 8. The third intense

band at ~390 nm is probably an envelope consisting of a

MLCT component similar to that in both the copper¹⁴and

nickel complexes and a d–d component, since it is roughly

coincident with the expected location of a d–d band. Support

for this hypothesis is obtained from spectra of related com-

plexes of cobalt (Table 8), where shoulders are seen emerg-

ing in several cases on the high-energy side of broad bands

at ~390 nm. For six-coordinate complexes of Co(III) with

less than octahedral symmetry, three d–d bands with inten-

sities that increase as the wavelength decreases are ex-

pected,^44,45and all spectra in Table 8 exhibit two bands with

intensity suitable for classification as d–d transitions in low-

symmetry six-coordinate Co(III) species. The separation be-

tween the observed bands places the anticipated third band

in each case roughly where the absorptions near 390 nm are

observed.

(DTTCE

=

1,11-dioxa-4,8,14,18-tetrathiacycloeicosane).⁴³

Like the IR spectrum of IV, a broad band at 3450 cm^–1in

the spectrum of V that is unshifted and of similar shape to

that of the free ligand suggests absence of hydrogen bonding

by the phenolic OH or the molecule of methanol and there-

fore a monomeric formulation for V like that of IV.

For VI, an N₂OS₂Cl coordination sphere with trans-nitrogens

is proposed by analogy to the X-ray structure of [Co(L3)][BF₄]

(XIX). However, in VI one site must be occupied by chlor-

ide instead of oxygen because of the difference between L3

and (L3-sal).

The five complexes derived from nickel bromide illustrate

the versatility of these ligands. For example, from one

reaction between L3 and NiBr₂·H₂O, three products were

isolated by solvent extractions and crystallization. The first,

[Ni(HL3)Br]·2H₂O (XI), has a mass spectrum with a peak

at m/z 525.0 corresponding to [C₂₀H₂₄BrN₂NiO₂S₂]⁺or

[Ni(HL3)Br + H⁺], which suggests an N₂OS₂Br coordination

sphere with trans-nitrogens but with the intact phenolic

group uncoordinated to the nickel atom. The second product

is [Ni(HL3-sal)Br]Br·CH₃OH (X). Its coordination sphere is

expected to consist similarly of an N₂OS₂Br donor set with

trans-nitrogens. In this case, however, the intact phenolic

group should be coordinated to the nickel atom. In the

mass spectrum, there is a peak at m/z 285.1 corresponding

to [C₁₃H₂₁N₂OS₂]⁺or [(HL3-sal) + H⁺], which is consistent

with the proposed organic ligand, but the spectrum contains

no peaks assignable to the complete coordination sphere.

The IR spectrum of the compound shows a broad band at

3450 cm^–1that is unshifted and of similar shape to that of

the free ligand, suggesting no hydrogen bonding involving

the free phenolic OH group or the molecule of methanol.

For {[Ni(HL1-sal)]Br₂}₂{[Ni(L1-sal)]Br}·H₂O (VII), the

proposed structure is suggested by the X-ray structure for

Published by NRC Research Press

Lucas et al.

Table 9. Cyclic voltammetric data for nickel complexes.

1187

Cyclic voltammetry vs saturated

calomel clectrode (SCE)^a

Coordination

sphere

Compound

DE_p(mV)

E_1/2(mV)

820

[Ni(HL3)]₂[BF₄]₂·CH₃CN (XIV)

[Ni(L3)·HOAc]₂[Ni(L3)·2HOAc]·3H₂O (III)

[Ni(L1)]·H₂O (I)

N₂O₂S₂

BrN₂OS₂

N₂OS₃

100^b

540^c

745

110

[Ni(HL2)][OAc] (II)

675^d

780

[Ni(HL3-sal)Br]Br·CH₃OH (X)

{[Ni(HL1-sal)]Br₂}₂{[Ni(L1-sal)]Br}·H₂O (VII)

{[Ni(HL2-sal)]Br₂}₂{[Ni(L2-sal)]Br}·2CH₃OH (VIII)

120

200

230

788

800

N₂O₂S₂

^aScan rate 25 mV/s unless otherwise noted.

^bScan rate 200 mV/s.

^cIrreversible oxidation only.

^dWeak cathodic activity only.

By analogy, and because of the similarity of the electronic

spectra of XVII, XVIII, and XIX, their coordination spheres

are proposed to be similar. The ethereal oxygen donor at the

midpoint of L2 in XVII is probably not coordinated, since

the electronic spectra of XIX, in which the donor set is

known by X-ray methods to be O₂S₂N₂, and of XVII are

closely similar. Finally, XX is expected to have an analogous

O₂S₂N₂coordination sphere in which one oxygen is phenolic

and the other is from methanol.

Fig. 7. Cyclic voltammograms of [Co(L3)][BF₄] (IV) vs SCE. Scan

rates: 400 mV/s (– – –), 200 mV/s (– · · –), 100 mV/s (- - -),

50 mV/s (· · ·), and 25 mV/s (—).

10

8

6

4

2

Cyclic voltammetry

Cyclic voltammetry of L1, L2, or L3 in CH₃CN reveals in

all cases irreversible oxidation at potentials ≥950 mV versus

the saturated calomel electrode (SCE). An irreversible reduc-

tion is observed for L1 and L2 at potentials ≤–750 mV vs

SCE, whereas for L3 irreversible reduction occurs at val-

ues ≤–800 mV vs SCE. Thus, all three ligands have an elec-

trochemical “window” from –750 to +950 mV vs SCE

within which metal-centred electrochemical activity of their

complexes may be observed. This window is substantially

different from that observed previously^26,43for similar chains

terminated by pyridyl or ethyl groups, and the narrower win-

dow in the present case restricts observable metal-centred ac-

tivity to Ni^III/IIcouples (Table 9).

For XIV, a redox wave at E_1/2= 820 mV vs SCE is

due to a Ni^III/IIrather than a Ni^II/Icouple, since the latter

typically appears near –0.7 to –0.9 V vs SCE,^26,46whereas

[Ni(DTBO)][BPh₄]₂·CH₃CN (DTBO = 1,10-diaza-4,7,13,16-

tetrathia-5,6:14,15-dibenzocyclooctadecane) exhibits a rever-

sible Ni^III/IIwave at 1.29 V vs SCE.⁴⁶

For VIII, E_1/2= 800 mV vs SCE, a value close to that ob-

served for XIV. For VIII, however, DE_p= 230 mV, signifi-

cantly larger than for XIV, indicating a decrease in

electrochemical reversibility for the process. The two most

prevalent reasons for increased DE_pare slow electron transfer

kinetics and chemical reactions by the oxidized or reduced

forms of the electroactive species. A priori, there is no reason

to expect significantly different reactivities in VIII compared

with XIV. Therefore, the change in DE_pmust derive from a

change in electron transfer kinetics. Whereas sulfur is known

for its ability to accommodate varying bond lengths and an-

gles,^13,30,31oxygen is not and it may be that slower electron

transfer kinetics are experienced in VIII because of one of

0

-2

-4

-6

-1600

-1200

-800

-400

0

400

Potential (mV)

the coordination sphere oxygens being ethereal and in the

middle of the hydrocarbon chain versus a terminal phenoxy

oxygen in XIV. For outer sphere redox processes, bond

lengths and angles must adjust to those of the product before

electron transfer occurs and this may be more difficult in

VIII than XIV. For I, which is expected to have an N₂O₂S₂

coordination sphere like XIV and VIII, the value of E_1/2is

smaller than that of either and its value of DE_pis comparable

to that of XIV, suggesting a nearly reversible Ni^III/IIprocess.

The difference in E_1/2between I and the other species (XIV

and VIII) is in the cathodic sense indicating I is less difficult

to oxidize. This is consistent with the fact that it is electri-

cally neutral, whereas in XIV and VIII the electroactive spe-

cies are cations. For II, there is a barely discernible cathodic

peak (~675 mV) at almost the same potential as comparable

peaks for XIV and VIII and metal-centred oxidation is not

observed. For VII, the value of E_1/2= 788 mV vs SCE,

when compared with I with E_1/2= 745 mV vs SCE, indicates

the greater ease of oxidation of I as anticipated from the rel-

ative overall Lewis basicity of the donor sets. The larger

value of DE_pfor VII relative to I can be attributed to the

smaller flexibility of the ligand in VII where all donors are

Published by NRC Research Press

1188

Can. J. Chem. Vol. 89, 2011

bound to the metal. In I, a potential donor remains free al-

lowing its ligand to adapt more readily to the changed bond

lengths and angles necessary for electron transfer thereby per-

mitting faster electron transfer kinetics and a smaller DE_p.

For X, comparison may be made to XIV, since both have

unipositive cations as the electroactive species and their coor-

dination spheres differ only by substitution of Br for an O.

Using Pauling electronegativities (Br 2.96 and O 3.44)⁴⁷as a

rough guide to donor basicity, the overall donor strength in X

(N₂OS₂Br) is greater than that in XIV (N₂O₂S₂) and the ease

of oxidation of X compared with XIV reflected in the magni-

tude of their relative E_1/2values is as expected. For III, the

only activity observed is an irreversible oxidation wave at

540 mV vs SCE from which no useful chemical information

can be obtained.

For [Co(L3)][BF₄] (XIX), the cyclic voltammograms

(Fig. 7) at scan rates varying between 25 and 400 mV/s are

symmetrical about E_1/2= –378 mV vs SCE, but show in-

creasing cathodic and anodic wave separations with scan rate

(DE_p= 115 mV at 25 mV/s; DE_p= 419 mV at 400 mV/s).

This is usually taken to indicate that the Co^III/IIprocess is

electrochemically quasi-reversible,⁴⁸indicating that it is

accompanied by a change in coordination number and (or)

coordination sphere geometry.⁴⁹Although six-coordinate

Co^II(S₄O₂) and Co^II(S₄N₂) species such as [Co(DTC)][ClO₄]₂

(DTC = 1,11-dioxa-4,8,14,18-tetrathiacycloeicosane)⁴³and

[Co(PTTD)][ClO₄]₂(PTTD = 1,12-bis(2-pyridyl)-2,5,8,11-

tetrathiadecane)⁵⁰are well known, so are five-coordinate

complexes such as [Co(15O5)(H₂O)₂]Cl₂·H₂O) (15O5 =

Conclusions

One-pot syntheses for three ligands are reported as well as

for 20 of their complexes. An unexpected metal-assisted hy-

drolysis of just one of a pair of imine functionalities in the

complexed ligands has been observed and its selectivity at-

tributed to steric hindrance of the second coordinated imine.

Electronic spectra of the ligands have been recorded and are

essentially invariant with solvent. There is no evidence for

solvolysis of any of the complexes and therefore by compari-

son of spectra of the ligands and of the complexes of known

structure, assignments of structures have been made with rea-

sonable confidence to those complexes for which X-ray data

could not be obtained. Cyclic voltammetry reveals the ability

of thioether sulfur to accommodate its Lewis acid–base be-

haviour to the demands of the metal atom to which it is at-

tached. The ligands form complexes in which their phenoxy

groups are sometimes deprotonated and sometimes not, an

explanation for which has been proposed. The electrochemi-

cal behaviour of the three ligands and eight of their com-

plexes has been measured and the ligands observed to have

an electrochemically useful window from –750 to +950 mV

vs SCE in CH₃CN. Alteration of the functional groups termi-

nating the ligand chains can, in some cases, substantially

change a ligand’s electrochemically useful window and hence

the kinds of metal-centred electrochemical activity that can

be observed for its complexes. For the complexes, trends in

E_1/2and DE_phave been qualitatively correlated with struc-

tural parameters.

1,4,7,10,13-pentaoxacyclopentadecane)

with

an

O₅

coordination sphere⁵¹and [Co(Me₆tren)Br]⁺(Me₆tren =

tris(2-dimethylaminoethyl)amine) with an N₄Br coordination

sphere¹⁷and many four-coordinate species. Dissociation of

one or more donors upon electrochemical reduction of Co

(III) to Co(II) is not therefore surprising and is consistent

with the tendency for Co(II) low-spin entities to undergo

Jahn–Teller distortion, which, in the extreme case, would

correspond to dissociation of donors at the sites of bond

elongation.

The observed value of E_1/2= –378 mV vs SCE for XIX

can be compared to those of [Co(HTC)][ClO₄]₂(HTC =

1,4,7,11,14,17-hexathiacycloeicosane)⁴³(E_1/2= +328 mV vs

SCE) with its S₆coordination sphere, [Co(HOten)][ClO₄]Cl₂

(HOten = 3-(2′-aminoethylthia)-2,2-bis((2″-aminoethylthia)

methyl)propan-1-ol)⁵²(E_1/2= –177 mV vs SCE) with its

N₃S₃coordination sphere, and [Co(HOsen]Cl₃·H₂O (HOsen =

3-(2′-aminoethylamino)-2,2-bis((2″-aminoethylamino)methyl)

propan-1-ol)⁵²(E_1/2= –539 mV v. SCE) with its N₆coordi-

nation sphere. The trend in these potentials qualitatively re-

flects the trend in ease of reduction of the Co(III) centres

and its relationship to the net s-donor ability or Lewis basic-

ity of the coordination sphere. Thus, the N₆coordination

sphere composed of strong s donors exhibits the highest

cathodic potential, indicating it to be the most difficult of

the complexes to reduce, whereas the S₆coordination sphere

has the least cathodic potential, indicating it to be the easiest

of the complexes to reduce. This trend is consistent with the

abilities of N, O, and S to act as hard or soft Lewis bases,

and, in particular, with the ability of sulfur to act either as

an electron source or sink depending upon the requirements

of the atoms to which it is bound.^26,53,54

Supplementary data

Supplementary data are available for this article through

the journal Web site at http://nrcresearchpress.com/doi/suppl/

10.1139/v11-081. CCDC 796013 and 796014 (for Co) and

801545 and 801546 (for Ni) contain the X-ray data in CIF

format for this manuscript. These data can be obtained, free

of charge, via http://www.ccdc.cam.ac.uk/cgi-bin/catreq.cgi

(Or from the Cambridge Crystallographic Data Centre, 12

Union Road, Cambridge CB2 1Ez, UK; fax +44 1223

336033; or deposit @ccdc.cam.ac.uk).

Acknowledgements

Funding for this work was provided by Memorial Univer-

sity of Newfoundland and by the Natural Sciences and Engi-

neering Research Council of Canada (NSERC).

References

(1) Germain, M. E.; Vargo, T. R.; McClure, B. A.; Rack, J. J.; Van

Patten, P. G.; Odoi, M.; Knapp, M. J. Inorg. Chem. 2008 47

(14), 6203. doi:10.1021/ic702469q.

(2) Paschke, R.; Liebsch, S.; Tschierske, C.; Oakley, M. A.; Sinn,

E. Inorg. Chem. 2003 42 (25), 8230. doi:10.1021/ic0301021.

(3) Kwok, C.-C.; Yu, S.-C.; Sham, I. H. T.; Che, C.-M. Chem.

Commun. (Camb.) 2004 (23): 2758. doi:10.1039/b412762e.

(4) Yang, Y.; Driesen, K.; Nockemann, P.; Van Hecke, K.; Van

Meervelt, L.; Binnemans, K. Chem. Mater. 2006 18 (16),

3698. doi:10.1021/cm060644r.

(5) Djukic, B.; Lemaire, M. T. Inorg. Chem. 2009 48 (22), 10489.

doi:10.1021/ic9015542.

(6) Koner, R.; Hazra, S.; Fleck, M.; Jana, A.; Lucas, C. R.;

Published by NRC Research Press

Lucas et al.

Mohanta, S. Eur. J. Inorg. Chem. 2009 2009 (33), 4982.

1189

(30) Lucas, C. R.; Liu, S.; Newlands, M. J.; Charland, J.-P.; Gabe,

E. J. Can. J. Chem. 1989 67 (4), 639. doi:10.1139/v89-096.

(31) Hartman, J. A.; Cooper, S. R. J. Am. Chem. Soc. 1986 108 (6),

1202. doi:10.1021/ja00266a014.

(32) Böttcher, A.; Takeuchi, T.; Hardcastle, K. A.; Meade, T. J.;

Gray, H. B.; Cwikel, D.; Kapon, M.; Dori, Z. Inorg. Chem.

1997 36 (12), 2498. doi:10.1021/ic961146v.

(33) Sreekanth, A.; Kala, U. L.; Nayar, C. R.; Prathapachandra

Kurup, M. R. Polyhedron 2004 23 (1), 41. doi:10.1016/j.poly.

2003.09.029.

doi:10.1002/ejic.200900686.

(7) Mitra, K.; Biswas, S.; Lucas, C. R.; Adhikary, B. Inorg. Chim.

Acta 2006 359 (7), 1997. doi:10.1016/j.ica.2006.01.013.

(8) Lucas, C. R.; Liang, W.; Miller, D. O.; Bridson, J. N. Inorg.

Chem. 1997 36 (20), 4508. doi:10.1021/ic961536h.

(9) Lucas, C. R.; Liu, S. Can. J. Chem. 1996 74 (11), 2340.

doi:10.1139/v96-261.

(10) Lucas, C. R.; Liu, S. J. Chem. Soc., Dalton Trans. 1994 (2),

185. doi:10.1039/dt9940000185.

(11) Liu, S.; Lucas, C. R.; Hynes, R. C.; Charland, J.-P. Can. J.

Chem. 1992 70 (6), 1773. doi:10.1139/v92-222.

(12) Wu, H.; Lucas, C. R. Inorg. Chem. 1992 31 (12), 2354. doi:10.

1021/ic00038a012.

(34) John, R. P.; Sreekanth, A.; Kurup, M. R. P.; Mobin, S. M.

Polyhedron 2002 21 (24), 2515. doi:10.1016/S0277-5387(02)

01227-5.

(35) Smucker, B. W.; VanStipdonk, M. J.; Eichhorn, D. M. J. Inorg.

Biochem. 2007 101 (10), 1537. doi:10.1016/j.jinorgbio.2007.

06.042.

(13) Adhikary, B.; Lucas, C. R. Inorg. Chem. 1994 33 (7), 1376.

doi:10.1021/ic00085a027.

(14) Lucas, C. R.; Byrne, J. M. D.; J.L. Collins, J. L.; Miller, D. O.

Can. J. Chem., in press.

(15) Dwyer, P. J.; Lions, F. J. Am. Chem. Soc. 1950 72, 1545.

(36) Solomons, T. W. G. Organic Chemistry; 3rd ed.; Wiley:

Toronto, 1984; pp 467–468.

(37) Bosnich, B. J. Am. Chem. Soc. 1968 90 (3), 627. doi:10.1021/

ja01005a012.

doi:10.1021/ja01160a033.

(16) Kaczmarek, M. T.; Pospieszna-Markiewicz, I.; Kubicki, M.;

Radecka-Paryzek, W. Inorg. Chem. Commun. 2004 7, 1247.

doi:10.1016/j.inoche.2004.09.022.

(17) Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochmann, M.

Advanced Inorganic Chemistry; 6th ed.; Wiley Interscience:

Toronto, 1999; p 822.

(38) Clark, H. C.; O’Brien, R. J. Can. J. Chem. 1959 37 (2), 436.

doi:10.1139/v59-057.

(39) Tas, E.; Kilic, A.; Konak, N.; Yilmaz, I. Polyhedron 2008 27

(3), 1024. doi:10.1016/j.poly.2007.11.038.

(40) Drago, R. S. Physical Methods for Chemists; 2nd ed.;

Saunders College Publishing: Toronto, 1992; p 194.

(41) Fraser, C.; Ostrander, R.; Rheingold, A. L.; White, C.;

Bosnich, B. Inorg. Chem. 1994 33 (2), 324. doi:10.1021/

ic00080a023.

(18) Hoshino, N.; Ito, T.; Nihei, M.; Oshio, H. Chem. Lett. 2002 31

(8), 844. doi:10.1246/cl.2002.844.

(19) Newton, G. N.; Cooper, G. J. T.; Long, D.-L.; Körgerler, P.;

Cronin, L. J. Mol. Struct. 2006 796 (1–3), 23. doi:10.1016/j.

molstruc.2006.03.087.

(42) Ahuja, I. S. Aust. J. Chem. 1968 21 (11), 2805. doi:10.1071/

CH9682805.

(20) Bluhm, M. E.; Folli, C.; Walter, O.; Döring, M. J. Mol. Catal.

Chem. 2005 229 (1–2), 177. doi:10.1016/j.molcata.2004.11.

015.

(43) Lucas, C. R.; Liu, S.; Bridson, J. N. Can. J. Chem. 1995 73 (7),

1023. doi:10.1139/v95-127.

(44) Lever, A. B. P. Inorganic Electronic Spectroscopy; Elsevier:

New York, 1968; p 308.

(21) Tandon, S. S.; Lucas, C. R. Can. J. Chem. 2008 86 (9), 912.

doi:10.1139/v08-100.

(45) Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochmann, M.

Advanced inorganic chemistry; 6th ed.; Wiley Interscience:

Toronto, 1999; p 825.

(22) Sygurova, M. K.; Romanenko, G. V.; Vostrikova, K. E.;

Vishnevetskaya, L. A.; Podberezskaya, N. V. J. Struct. Chem.

1995 36 (5), 860. doi:10.1007/BF02579682.

(46) De Vries, N.; Reedijk, J. Inorg. Chem. 1991 30 (19), 3700.

(23) Xu, L.; Ye, Q.; Li, H.; Jiao, K.; Zhang, S. J. Chem.

Crystallogr. 2000 30 (7), 463. doi:10.1023/A:1011351500225.

(24) García-Antón, J.; Pons, J.; Solans, X.; Font-Bardia, M.; Ros, J.

Eur. J. Inorg. Chem. 2003 2003 (16), 2992. doi:10.1002/ejic.

200300035.

(25) Ladd, M. F. C.; Larkworthy, L. F.; Leonard, G. A.; Povey, D.

C.; Tandon, S. S. J. Cryst. Spectr. Res. 1985 15 (1), 19. doi:10.

1007/BF01185713.

doi:10.1021/ic00019a026.

(47) Allred, A. L. J. Inorg. Nucl. Chem. 1961 17 (3–4), 215. doi:10.

1016/0022-1902(61)80142-5.

(48) Bard, A. J.; Faulkner, L. R. Electrochemical Methods,

Fundamentals and Applications; Wiley: New York, 1980.

(49) Headridge, J. B. Electrochemical Techniques for Inorganic

Chemists; Academic Press: London, 1969.

(50) Adhikary, B.; Liu, S.; Lucas, C. R. Inorg. Chim. Acta 1997

261 (1), 15. doi:10.1016/S0020-1693(96)05572-7.

(51) Streltsova, N. R.; Besky, V. K.; Bulychev, V. M.; Kireeva, O.

K. Inorg. Chim. Acta 1991 189, 111. doi:10.1016/S0020-1693

(00)80396-5.

(26) Adhikary, B.; Liu, S.; Lucas, C. R. Inorg. Chem. 1993 32 (26),

5957. doi:10.1021/ic00078a011.

(27) Grant, G. J.; Jones, M. W.; Loveday, K. D.; VanDerveer, D. G.;

Pennington, W. T.; Eagle, C. T.; Mehne, L. F. Inorg. Chim.

Acta 2000 300–302, 250. doi:10.1016/S0020-1693(99)00602-

7.

(52) Bernhardt, P. V.; Kim, Y.; Sujandi. Aust. J. Chem. 2006 59

(11), 783. doi:10.1071/CH06257.

(28) Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry,

Principles of Structure and Reactivity; 4th ed.; Harper Collins:

New York, 1993; p 301.

(53) Lucas, C. R. Can. J. Chem. 1983 61 (6), 1096. doi:10.1139/

v83-194.

(54) Lucas, C. R. Can. J. Chem. 1986 64 (9), 1758. doi:10.1139/

(29) Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry,

Principles of Structure and Reactivity; 4th ed.; Prentice Hall:

Toronto, 1997; p 292.

v86-290.

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Article Doi

Cobalt and nickel complexes of open-chain thioether ligands terminated by salicylaldimine functionality

DOI: 10.1139/v11-081

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Article abstract of DOI:10.1139/v11-081

Full text of DOI:10.1139/v11-081

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