WO1996015136A1

WO1996015136A1 - Novel mn(ii) carboxylate complexes, processes for their preparation and their use as disproportionation catalysts

Info

Publication number: WO1996015136A1
Application number: PCT/IE1995/000059
Authority: WO
Inventors: Michael Devereux; Martin Curran; Malachy Mccann; Michael Casey
Original assignee: MAYNOOTH UNIVERSITY ENTERPRISE DEVELOPMENT Ltd; Technological University Dublin
Current assignee: MAYNOOTH UNIVERSITY ENTERPRISE DEVELOPMENT Ltd; Technological University Dublin
Priority date: 1994-11-14
Filing date: 1995-11-14
Publication date: 1996-05-23
Anticipated expiration: 1997-05-14
Also published as: AU3880395A; EP0804444A1

Abstract

The present invention concerns novel maganese (II) carboxylate complexes having utility as disproportionation catalysts and processes for their preparation. The invention provides Mn(II) carboxylate complexes or their binuclear or polynuclear derivatives, in which the carboxylate moiety is of the general formula: Y[Om(CH2)qCOOH]p in which m is 0 or 1; q is » 0; p is » 1; and Y, which may be substituted or unsubstituted, is selected from lower alkyl, lower alkenyl, lower alkynyl, a carbocyclic ring system, an aromatic hydrocarbon or a heterocyclic ring system and, when p is 2, Y, which may also be substituted or unsubstituted, is additionally selected from lower alkylene, lower alkenylene or lower alkynylene, with the proviso that, when m is 0 and q is 0 or 1 and p is 1, Y is not hydrogen.

Description

NOVEL MN(II) CARBOXYLATE COMPLEXES, PROCESSES

FOR THEIR PREPARATION AND THEIR USE AS

DISPROPORTIONATION CATALYSTS

Introduction The present invention concerns novel manganese (II) carboxylate complexes, processes for their

preparation and their use as disproportionation

catalysts. More specifically, the novel complexes of the present invention are mono-, di- and polycarboxylate complexes of manganese (II) which may, optionally, contain nitrogen and/or oxygen donor ligands. The present invention also concerns the use of the said complexes as catalysts for the

disproportionation of hydrogen peroxide or the like hydrogen peroxide-liberating or generating

percompounds. The novel complexes of the invention have advantages over other known manganese complexes that have been employed as peroxide disproportionation catalysts in that (i) they are easily synthesised from cheap, readily available starting materials and (ii) they are extremely reactive towards hydrogen peroxide.

According to a first aspect of the invention there is provided a Mn(II) carboxylate complex or a binuclear or polynuclear derivative thereof, in which the

carboxylate moiety is of the general formula Y[O_m(CH₂)_qCOOH]_p in which m is 0 or 1; q is ≥ O; p is ≥ 1; and Y is selected from the group comprising hydrogen,

substituted or unsubstituted lower (C_1-20) alkyl, substituted or unsubstituted lower (C_2-20) alkenyl, substituted or unsubstituted lower (C_2-20) alkynyl, substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated carbocyclic ring system, substituted or unsubstituted mono-, bi- or polycyclic aromatic hydrocarbon or substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated heterocyclic ring system and, when p is 2, Y

additionally is selected from the group comprising substituted or unsubstituted lower (C_1-20) alkylene, substituted or unsubstituted lower (C_2-20) alkenylene or substituted or unsubstituted lower (C_2-20)

alkynylene; with the proviso that, when m is 0 and q is 0 or 1 and p is 1, Y is not hydrogen.

Preferably Y is substituted by halogen, hydroxyl, lower (C_1-20) alkoxy, nitro, a substituted or

unsubstituted mono-, bi- or polycyclic saturated or unsaturated carbocyclic ring system, a substituted or unsubstituted mono-, bi- or polycyclic aromatic

hydrocarbon or a substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated heterocyclic ring system. More preferably Y is a carbocyclic ring system selected from the group comprising lower (C_3-20) cycloalkyl or a mono-, bi- or polyunsaturated derivative thereof, a fused bi- or polycyclic ring system, a bridged bi- or polycyclic ring system, optionally selected from bi- and polycyclic terpenes, and a bi- or polyspiro ring system. Advantageously, the terpene is norbornene.

Advantageously Y is a substituted or unsubstituted mono-, bi- or polycyclic aromatic hydrocarbon,

preferably C_6-12 aryl, optionally selected from phenyl, benzyl, naphthalenyl and anthracenyl, Y being

optionally substituted by halogen, hydroxyl, lower (C_1-20) alkoxy or nitro.

More advantageously, Y is naphthalenyl or

2-hydroxy-1- phenyl or, alternatively, Y is (C_1-10) lower alkylene, optionally selected from dimethylene, trimethylene, tetramethylene, pentamethylene and hexamethylene; p is 2; and m and q are each 0. Preferably Y is lower (C_2-20) alkenyl substituted by halogen, hydroxyl, lower (C_1-20) alkoxy, nitro, a substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated carbocyclic ring system, a substituted or unsubstituted mono-, bi- or polycyclic aromatic hydrocarbon or a substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated heterocyclic ring system. More preferably Y is a lower (C₂-₁₀) alkenyl, optionally acrylyl, substituted by a heterocyclic ring system, most preferably

imidazol-4-yl. Preferably, the Mn(II) carboxylate complex

additionally comprises at least one nitrogen donor ligand selected from substituted or unsubstituted saturated or unsaturated ring nitrogen-containing mono-, bi-, or polycyclic ring systems, ammonia, substituted or unsubstituted primary, secondary and tertiary amines or bi- or polycyclic fused ring

systems. More preferably, the nitrogen donor ligand is selected from substituted or unsubstituted pyridine, 1,10-phenanthroline and 2,2'-bipyridine.

Advantageously, the Mn(II) carboxylate complex additionally comprises at least one oxygen donor ligand optionally selected from water, hydronium ions and lower (C_1-20) alkanols, preferably ethanol.

According to a second aspect of the invention there is provided a process for the preparation of a Mn(II) carboxylate complex as defined hereinabove, which process comprises reacting a Mn(II) salt of the formula

Mn (II) L in which L is a leaving group which may optionally be selected from acetate and halogen, preferably chloride, with an appropriate carboxylic acid, or a salt thereof, in a suitable reaction medium, preferably selected from water or an ethanol:water mixture, more preferably a 4:1 (v:v) ethanol:water mixture, to obtain the Mn(II) carboxylate complex. The invention also provides a process for the preparation of a Mn(II)-carboxylate-nitrogen donor ligand complex as defined hereinabove, which process comprises:

(i) (a) reacting a Mn(II) salt of the formula

Mn(II)L

in which L is a leaving group which may optionally be selected from acetate and halogen, preferably chloride, with an appropriate carboxylic acid, or a salt thereof, in a suitable reaction medium, preferably selected from water or an ethanol : water mixture, more preferably a 4:1 (v:v) ethanol : water mixture, to obtain a Mn(II) carboxylate complex; and

(i) (b) reacting the Mn(II) carboxylate complex with an appropriate nitrogen donor ligand to obtain the Mn(II)-carboxylate-nitrogen donor ligand complex of the invention; or

(ii) reacting a Mn(II) salt of the formula

Mn(II)L

in which L is a leaving group which may optionally be selected from acetate and halogen, preferably chloride, with an appropriate carboxylic acid, or a salt thereof, in a suitable reaction medium, preferably selected from water or an ethanol:water mixture, more preferably a 4:1 (v:v) ethanol:water mixture, the reaction medium also containing an appropriate nitrogen donor ligand, to obtain the Mn(II)-carboxylate-nitrogen donor ligand complex of the invention.

According to a third aspect of the invention there is provided use of Mn(II) carboxylate complexes as defined hereinabove as disproportionation catalysts.

According to a fourth aspect of the invention there is provided a catalyst for accelerating the disproportionation of hydrogen peroxide, hydrogen peroxide-liberating percompounds and hydrogen

peroxide-generating percompounds, the catalyst

comprising a Mn(II) carboxylate complex as defined hereinabove.

The term "carboxylate" when used in the

expressions "Mn(II) carboxylate complex" and

"Mn(II)-carboxylate-nitrogen donor complex" and the like expressions is intended to embrace mono-, bi- and poly-carboxylate complexes.

The term "hydrogen peroxide percompound" is intended to embrace alkali metal peroxides, as well as alkali metal perborates, percarbonates, perphosphates and persulphates.

General Preparation of the Manganese (II) Carboxylate Complexes of the Invention Method (a): The Two-Stage Synthetic Route:

A simple manganese (II) salt (eg. manganese (II) acetate tetrahydrate or manganese (II) chloride

tetrahydrate) is reacted with an excess of the

appropriate carboxylic acid (or the sodium salt of the acid) in water or an ethanol:water mixture (4:1) (v:v) to give a suspension (or a solution) of the respective manganese (II) carboxylate complex in high yield. This manganese (II) carboxylate complex may then be added to a solution of a selected nitrogen donor base (N-base) to give the respective manganese (II) carboxylate/N-base complex in good yield.

Method (b) : The Single-stage Synthetic Route:

tetrahydrate) is reacted with an excess of the

appropriate carboxylic acid (or the sodium salt of the acid) in water or an ethanol:water mixture (4:1) (v:v) containing the dissolved nitrogen donor base (N-base). The respective manganese (II) carboxylate/N-base complex is isolated in good yield.

ABBREVIATIONS odaH₂= octanedioic acid; salH₂ = salicylic acid; ndaH₂ = cis-5-norbornene-endo-2,3-dicarboxylic acid; bdoaH₂ = benzene-1,2-dioxyacetic acid; bndaH₂=

1,1'-binaphtho-2,2'-diacetic acid; bdaH₂= butanedioic acid; phen = 1,10-phenanthroline; py = pyridine; bipy = 2,2'-bipyridine; E-uro = E-urocanic acid (E-4-imidazole acrylic acid).

Detailed Preparation of the Manganese (II) Carboxylate Complexes of the Invention

Example 1: Mn(oda).H₂O (Complex 1) Mn(CH₃CO₂)₂·4H₂O (1.0 g, 4.08 mmol) and

octanedioic acid (0.825 g, 4.74 mmol) were refluxed together in an ethanol:water mixture (4:1) (100 ml) for 2 h. The white product (1) was filtered off, washed with ethanol and then air-dried. Yield 76%. Calc: C, 39.19; H, 5.76. Found: C, 39.64; H, 5.63%; IR (CsI matrix) : 3550, 2940, 1560, 1420, 1355, 1190, 1000, 810, 710, 425 cm^-1. Complex (1) was insoluble in all common solvents.

Example 2: [Mn₂(oda)(phen)₄(H₂O ) ₂] [Mn₂(oda)₃

(phen)₄].4H₂O (Complex 2)

Complex (1) (0.5 g, 2.04 mmol) and

1,10-phenanthroline (1.13 g, 6.27 mmol) were refluxed together in an ethanol:water mixture (4:1) (50 ml) for 45 min. The resulting yellow solution was allowed to cool to room temperature and on standing the product (2) formed as yellow crystals. The crystals were filtered off, washed with ice-cold ethanol and then air-dried. Yield 51%. More of complex (2) was

obtained upon concentration of the reaction filtrate. Overall yield of (2) was 80%. Calc: C, 62.54; H, 5.08; N, 9.12. Found: C, 61.34; H, 5.03; N, 8.69%; IR (CsI matrix) : 3400, 2940, 1570, 1520, 1425, 870, 850, 730 cm^-1; Uv/vis: λ_max (H₂O) 345 nm (sh). Complex (2) readily dissolves in warm water and in warm ethanol.

Example 3: [Mn₂(salH)₄(H₂O)₄] (Complex 3)

To a solution of NaOH (0.436 g, 10.9 mmol) in water (150 ml) was added salicylic acid (1.513 g, 10.9 mmol) and MnCl₂.4H₂O (1.039 g, 5.3 mmol). The

resulting solution was refluxed for 3 hours and then concentrated to ca. 50 ml. On standing for a few days at room temperature, complex (3) formed as colourless crystals in essentially quantitative yield. IR (KBr matrix): 3700, 1630, 1540, 1480, 1410 cm^-1. Complex (3) was soluble in water, ethanol, methanol,

dimethylfuran and tetrahydrofuran and insoluble in diethyl ether.

Example 4: [{Mn₂(sal)₂(salH)(H₂O)(H₃O)(py)₄.2py}_n]

(Complex 4)

A dark-green solution of complex (3) (1.0 g, 1.37 mmol) in pyridine (25 ml) was refluxed for 0.5 h. After cooling to room temperature, the solution was

concentrated in vacuo to give dark green crystals of complex (4). The solid was filtered off, washed with diethyl ether and then air-dried. Yield 60%. IR (KBr matrix) : 3700, 1620, 1560, 1535, 1440 cm^-1; UV-vis (in EtOH) :λmax= 561 nm, Σ = 276 dm³ mol^-1cm^-1. Complex (4) was soluble in ethanol, acetone, pyridine and dimethyl sulphoxide and insoluble in diethyl ether. Example 5: [{Mn(salH)₂(bipy)(H₂O)}_n] (Complex 5)

To a solution of complex (3) (0.4 g, 0.55 mmol) in an ethanol:water mixture (4:1) (50 ml) was added 2,2'-bipyridine (0.2 g, 1.28 mmol), and the resulting mixture was refluxed for 1 hr. On standing for a number of days, the pale green solution yielded yellow

crystals of (5). The solid was filtered off, washed with a small portion of ethanol and then air-dried at ca 20°C. Yield (15%). Calc: C, 57.3; H, 4.0; N, 5.6% Found: C, 57.5; H, 4.0; N, 5.71%. IR (CsI matrix):

3580, 3520, 3060, 1600, 1490, 1440, 1390, 1350, 1240, 1150, 1030, 1020, 850, 760, 705, 660, 570, 540, 470, 390 cm^-1. Complex (5) was readily soluble in aqueous ethanol, hot water and hot ethanol.

Example 6: [Mn(salH)₂(phen)] (Complex 6)

To a solution of complex (3) (0.4 g, 0.548 mmol) in an ethanol:water mixture (4:1) (50 ml) was added 1,10-phenanthroline (0.23 g, 1.276 mmol). The mixture was stirred at room temperature for 2 hours and, upon standing, the green product precipitated. The solid was filtered off, washed with a small portion of ethanol and then air-dried at ca 20°C. Yield 55%.

Calc: C, 61.30; H, 3.54; N, 5.50. Found: C, 61.20; H, 3.69; N. 5.77%. IR(CsI matrix): 3420, 3070, 1660, 1600, 1490, 1470, 1395, 1350, 1260, 870, 765 cm^-1. Complex (6) readily dissolves in hot ethanol and in hot water.

Example 7: [Mn(nda)(H₂O)] (Complex 7) To a solution of ndaH₂(1.0 g, 5.49 mmol) and NaOH (0.48 g, 12.0 mmol) in distilled water (100 ml) was added MnCl₂.4H₂O (0.98 g, 4.96 mmol). The resulting colourless solution was stirred at room temperature for 3 hours. The solution was concentrated by slow

evaporation to yield the product as light pink

crystals. The solid was filtered off, washed with a small volume of cold water and then air-dried at ca 25°C. Yield 0.94 g (75%). Calc: C, 42.7; H, 3.99.

Found: C, 42.5; H, 3.94%. IR (CsI matrix): 3410, 3000, 1650, 1550, 1480, 1430, 1350, 1315, 1250, 800, 655 cm^-1. Complex (7) was insoluble in all common

solvents.

Example 8: [Mn(η¹η¹-nda)(phen)₂].EtOH.H₂O (Complex 8)

To a suspension of complex (7) (0.37 g, 1.46 mmol) in an ethanol:water mixture (4:1) (100 ml) was added

1,10-phenanthroline (1.5 g). The resulting mixture was refluxed for 0.75 hours to give a yellow solution. Upon standing for several days, yellow crystals of the product (8) were deposited. The solid was filtered off, washed with a small portion of ice-cold ethanol and air-dried at ca 25°C. Yield 0.25g (65.4%). Calc: C, 63.73; H, 4.90; N, 8.50. Found: C, 64.56; H, 4.66; N, 8.40%. IR (CsI matrix): 3800, 3000, 1610, 1590, 1545, 1520, 1430, 1400, 1375, 1350, 1305, 1290, 1100, 860, 750, 735, 640 cm^-1. Complex (8) readily dissolves in water and in warm ethanol.

Example 9: [Mn(bdoa)(H₂O)₃] (Complex 9) To a solution of bdoaH₂(2.55 g, 11.3 mmol) in an ethanol:water mixture (4:1) (100 ml) was added

Mn(CH₃CO₂)₂.4H₂O (2.55 g, 10.4 mmol). The mixture was refluxed for 2 hours. Upon cooling a colourless solid precipitated. This crude material was filtered and recrystallised from hot water to give colourless crystals of (9). The solid was filtered off, washed with a small portion of ice-cold ethanol and air-dried at ca 25°C. Yield 89.4%. Calc: C, 36.05, H, 4.24.

Found: C, 39.67; H, 3.16%. IR (CsI matrix): 3400, 1600, 1505, 1420, 755 cm^-1. Complex (9) was soluble in hot water and in ethanol.

Example 10: [Mn(bdoa)(phen)₂(H₂O)] (Complex 10)

To a solution of complex (9) (0.4 g, 1.2 mmol) in an ethanol:water mixture (4:1) (50ml) was added

1,10-phenanthroline (0.65 g, 3.6 mmol). The mixture was refluxed for 2 hours and upon cooling the yellow product (10) precipitated. The solid was filtered off, washed with cool ethanol, and air-dried at ca 20°C.

Yield 70%. Calc: C, 62.10; H, 4.00; N. 8.52. Found: C, 62.00; H, 4.30; N. 8.13%. IR (CsI matrix) 3400, 3050, 2960, 1635, 1500, 1420, 840, 720 cm^-1. Complex (10) was soluble in water and in methanol.

Example 11: [Mn(bnda)(H₂O)₃] (Complex 11)

To a solution of Mn(CH₃CO₂)₂.4H₂O (0.25 g, 1.02 mmol) in an ethanol:water mixture (4:1) (50 ml) was added bndaH₂(0.45 g, 1.12 mmol). The mixture was refluxed for 2 hours and allowed to cool. The solid was filtered off, washed with ethanol and air-dried at ca 20°C. Yield 78%. Calc: C, 56.58; H, 4.37. Found: C, 56.48; H, 3.44%. IR (CsI matrix): 3380, 3040, 1590, 1420, 1215 cm^-1. Complex (11) was insoluble in water and in ethanol.

Example 12: [Mn(bnda)(phen)₂(H₂O)₂] (Complex 12) To a suspension of complex (11) (0.5 g, 0.98 mmol) in an ethanol:water mixture (4:1) (100 ml) was added 1,10-phenanthroline (1.2 g, 6.67 mmol). The resulting mixture was then refluxed for 2 hours. Upon cooling the light-green solution was filtered and, on standing for several days, green crystals of the product formed. The solid was filtered off, washed with ice-cold ethanol and then air-dried at ca 20°C. Calc: C, 67.79; H, 4.23; N. 6.58. Found: C, 67.79; H, 3.70; N, 6.62%. IR (CsI matrix) : 3400, 3040, 1615, 1420, 1270, 845 cm^-1. Complex (12) was only sparingly soluble in hot ethanol and was insoluble in water.

Example 13: [Mn(bda)(H₂O)₂] (Complex 13)

To a solution of Mn(CH₃CO₂)₂.4H₂O (0*4 g, 1 . 63 mmol) in an ethanol : water mixture (4:1) (50 ml) was added bdaH₂ (0.23g, 1.95 mmol). The mixture was refluxed for 2 hours and on cooling a colourless precipitate formed. The solid was filtered, washed with ethanol and was air-dried at ca 20°C. Yield 68%. Calc: C, 23.2; H, 3.9. Found: C, 22.2; H. 3.2%. IR (CsI matrix): 3200, 1570, 1380, 1220, 650 cm^-1. Complex (13) was readily soluble in water.

Example 14: [Mn(E-uro)₂(H₂O)₄] (Complex 14)

NaOH(0.2 g, 5.0 mmol) was dissolved in water

(100 ml) and E-urocanic acid (0.9 g, 6.5 mmol) was added. The mixture was stirred for 3 h and then

filtered. To the colourless filtrate was added

MnCl₂.4H₂O (0.43 g, 2.17 mmol), and the mixture was then stirred for 2 h. The resulting white solid product was filtered off, washed twice with water and then left to air-dry at ca 25°C. Yield 0.7 g (80%). Found: C, 36.2; H, 4.6; N, 13.8%. Calc: C, 35.9; H, 4.5; N, 13.9%; μ = 5.94 B.M.; IR (CsI matrix): 3350, 3095, 2860, 1660, 1530, 1480, 1380, 1345, 1260, 1170, 1120, 1000, 970, 955, 880, 850, 790, 685, 660, 400 cm^-1.

Complex (14) was soluble in warm water and insoluble in alcohols.

NOTE: All of the complexes (1)-(14) had magnetic moments in the range expected for simple manganese (II) species, i.e., those lacking Mn-Mn interactions. Example 15: X-RAY CRYSTALLOGRAPHIC STUDIES

The structures of complexes (2), (3), (4), (5), (8), (9) and (14) have been determined using X-ray crystallography, and these are described below.

[Mn₂(oda) (phen)₄(H₂O)₂] [Mn₂(oda)₃(phen)₄].4H₂O (Complex 2)

This complex comprises a dimanganese (II, II) dianion and a dimanganese (II, II) dication. In the dianion [Mn₂(oda)₃(phen)₄]^2-, each of the two symmetry related Mn(II) atoms are ligated by the nitrogen atoms of two chelating phen groups. An oda^2- ligand bridges the two metals by using one carboxylate oxygen from each end of the dicarboxylate ligand. A monodentate oda^2- ligand is coordinated to each metal via a single carboxylate oxygen, and this is in a cis position with respect to the bridging carboxylate oxygen. The three remaining oxygen atoms of this oda^2- ligand remain uncoordinated . Overall, in the dianion each Mn(II) atom is at the centre of a distorted N₄O₂ octahedron. The structure of the dication [Mn₂(oda)(phen)₄(H₂O)₂]²⁺ is basically similar to that of the dianion in that each of the two symmetry related Mn(II) atoms has a distorted

octahedral N₄O₂ coordination geometry. Each metal is surrounded by two chelating phen groups and one

carboxylate oxygen atom from the bridging oda^2- ligand. The sixth coordination site is occupied by the oxygen atom of a water molecule which, again, is in a cisoid position with respect to the coordinated carboxylate oxygen atom of the bridging oda^2- ligand.

[Mn₂(salH)₄(H₂O)₄] (Complex 3) The complex comprises two associated and symmetry related pseudo seven-coordinate Mn(II) centres. Each Mn is asymmetrically chelated by two salH- (HOC₆H₄CO2-) ligands and, perpendicular to the central plane, there are two coordinated water molecules. Association of the two metals occurs via the carboxylate oxygen atoms from a second pair of chelating salH- ligands,

effectively creating two asymmetric bridges between the Mn atoms. The stability of complex (3) in the solid state is further enhanced by intramolecular hydrogen bonding between the hydroxyl groups of the salH- function and one carboxylate oxygen of the same ligand. [{Mn₂(sal)₂(salH) (H₂O) (H₃O) (py)₄.2py}_n] (Complex 4)

The complex comprises three independent Mn(II) atoms {Mn1, Mn2 and Mn3 } in a polymeric system of the type

Mn1... Mn3... Mn2...Mn3... Mn1... Mn3... Mn2... Mn3... Mn1..

Mn1 lies on an inversion centre and is bonded to a carboxyl oxygen atom and a hydroxyl oxygen atom {both from a sal^2- ligand (sal^2- = OC₆H₄CO2^2-)} and also to a pyridine nitrogen. Mn2 lies on another inversion centre and it has an N₂O₄ octahedral coordination geometry identical to that of Mn1. Mn3 is in a general position, and is bonded to the second carboxylate oxygen atom from the sal^2- ligand which is coordinated to Mn1, and also to the second carboxylate oxygen atom from the sal^2- ligand which is coordinated to Mn2. The coordination mode of the carboxylate moieties of both of these bridging sal^2- ligands is syn-anti bidentate. The oxygen atom of a water molecule and the oxygen atom of a cisoid hydronium ion (H₃O⁺: oxygen donor ligand) are also coordinated to Mn3 , and the N₂O₄ octahedral coordination about the metal is completed by two axial pyridine ligands. Furthermore a salH- ion is hydrogen bonded via its carboxylate oxygens in a syn-syn

bidentate bridging mode to the water molecule and to the hydronium ion which are coordinated to Mn3.

Additional inter-ligand hydrogen bonding interactions are also present. Two pyridine molecules of solvation are also present in the lattice. The emperical formula of (4) is Mn₂(sal)₂(salH)(H₂O) (H₃O)(py)₄.2py. [{Mn(salH)₂(bipy) (H₂O)}_n] (Complex 5)

This is a polymeric complex, with each manganese ion at the centre of a distorted octahedron and ligated by both nitrogen atoms of a bipyridine and one

carboxylate oxygen from each of four salicylate

ligands. The salicylate carboxylate groups each form asymmetric bridges to further manganese atoms, forming spiral chains parallel to the two- fold screw axis.

[Mn(η¹η¹-nda) (phen)₂].EtOH.H₂O (Complex 8)

The complex comprises a single manganese (II) atom in a distorted six-coordinate geometry. The metal is ligated by two chelating phenanthroline ligands and two carboxylate oxygen atoms (one from each of the two carboxylate functions on the nda^2- ligand). The water molecule is hydrogen bonded to one of the free carbonyl oxygens of the nda^2- ligand. The ethanol molecule is hydrogen bonded to this water molecule.

[Mn(bdoa) (H₂O)₃] (Complex 9)

The complex comprises a single seven-coordinate manganese (II) ion. The bdoa^2- acts as a chelating quadridentate ligand and is bound to the metal via the two ethereal oxygen atoms and two carboxylate oxygens, one from each end of the diacid. The remaining three coordination sites are occupied by the oxygen atoms of three water molecules. [Mn ( E-uro ) ₂ (H₂O) ₄ ] ( Complex 14 )

This complex shows two distinct isomers of

[Mn(E-uro)₂(H₂O)₄]. One isomer has the imine nitrogen atom of the imidazole ring lying in a cisoid

orientation with respect to the carbon-carbon double bond which bears the pendant carboxylate group, whilst in the other isomer the same nitrogen atom is transoid to the double bond. Both species are centrosymmetric, so that the asymmetric unit comprises two independent half molecules. The geometry at manganese is

approximately octahedral, with the metal coordinated by the imine nitrogen atoms from two urocanate anions trans to one another, and also by four water molecules.

Example 16: H₂O₂ Disproportionation Results for

Complexes (1) - (14)

Disproportionation reaction

2H₂O₂ ->> 2H₂O + O₂

All of the complexes (1) - (14) disproportionated H₂O₂ in the presence of imidazole, and the results of these reactions are set out in Table 1 hereinafter. It should be noted that the base imidazole itself causes only a very slight disproportionation of hydrogen peroxide (see Table 1) and this sluggish reaction is greatly enhanced when the manganese complexes of the invention are included in the reaction mixture. In addition to their ability to disproportionate hydrogen peroxide, the complexes of the invention readily catalytically disproportionated sodium perborate tetrahydrate {NaBO₃.4H₂O} and sodium percarbonate {Na₂CO₃.1.5H₂O₂}.

EXPERIMENTAL CONDITIONS:

The reaction flask was equipped with a magnetic stirring bar and thermostatted at 25°C. Solid complex (ca 10 mg) and solid imidazole (50 mg) were added to the flask, and then aqueous H₂O₂ (35% w/w, 10 ml, 114 mmol) was injected using a syringe. The resulting mixture was stirred, and the evolved O₂ was measured volumetrically (ml) over a period of time (min). The results are set out in Table 1 hereinbelow.

Example 17 : H₂O₂ Disproportionation Results for

Complexes (2) and (8).

Data are given in Table 2 for the disproportionation of H₂O₂ by complexes (2) and (8) in the absence of imidazole.

EXPERIMENTAL CONDITIONS: The reaction flask was equipped with a magnetic stirring bar and thermostatted at 25°C. Solid complex (ca 10 mg) was added to the flask, and then aqueous H₂O₂ (35% w/w, 5 ml, 57 mmol) was injected using a syringe. The resulting mixture was stirred, and the evolved O₂ was measured volumetrically (ml) over a period of time (min) (see Table 2 annexed).

As will be observed from Table 2 (hereinafter), the complexes of the invention also catalyze the disproportionation of H₂O₂ in the absence of imidazole.

Example 18

Mn (II) carboxylate complexes of the present invention have been tested in contact with various stains such as tea, coffee and red wine. It is been shown, in these tests, that the complexes of the invention act as effective bleaching catalysts, either in the presence of a nitrogen donor ligand such as imidazole or

1,10-phenanthroline or in the absence of a nitrogen donor ligand. Accordingly, Mn (II) carboxylate

complexes of the present invention are suitable for use in surface cleaners and washing powders.

Claims

CLAIMS :

1. A Mn(II) carboxylate complex or a binuclear or

polynuclear derivative thereof, in which the carboxylate moiety is of the general formula

Y [O_m ( CH₂ ) _qCOOH] _p in which m is 0 or 1; q is ≥ 0; p is ≥ 1; Y is selected from the group comprising hydrogen, substituted or unsubstituted lower (C_1-20) alkyl, substituted or unsubstituted lower (C_2-20)

alkenyl, substituted or unsubstituted lower

(C_2-20) alkynyl, substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated carbocyclic ring system, substituted or

unsubstituted mono-, bi- or polycyclic aromatic hydrocarbon or substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated

heterocyclic ring system and, when p is 2, Y additionally is selected from the group comprising substituted or unsubstituted lower (C_1-20)

alkylene, substituted or unsubstituted lower

(C_2-20) alkenylene or substituted or unsubstituted lower (C_2-20) alkynylene; with the proviso that, when m is 0 and q is 0 or 1 and p is 1, Y is not hydrogen.

2. A Mn(II) carboxylate complex according to Claim 1, in which Y is substituted by halogen, hydroxyl, lower (C_1-20) alkoxy, nitro, a substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated carbocyclic ring system, a

substituted or unsubstituted mono-, bi- or polycyclic aromatic hydrocarbon or a substituted or unsubstituted mono-, bi- or polycyclic

saturated or unsaturated heterocyclic ring system.

3. A Mn(II) carboxylate complex according to Claim 1 or 2, in which Y is a carbocyclic ring system selected from the group comprising lower (C_3-20) cycloalkyl or a mono-, bi- or polyunsaturated derivative thereof, a fused bi- or polycyclic ring system, a bridged bi- or polycyclic ring system, optionally selected from bi- and polycyclic terpenes, and a bi- or polyspiro ring system.

4. A Mn(II) carboxylate complex according to Claim 3, in which Y is norbornene.

5. A Mn(II) carboxylate complex according to Claim 1 or 2 in which Y is a substituted or unsubstituted mono-, bi- or polycyclic aromatic hydrocarbon, preferably C_6-12 aryl, optionally selected from phenyl, benzyl, naphthalenyl and anthracenyl.

6. A Mn(II) carboxylate complex according to Claim 5, in which Y is substituted by halogen, hydroxyl, lower (C_1-20) alkoxy or nitro.

7. A Mn(II) carboxylate complex according to Claim 6, in which Y is naphthalenyl or 2-hydroxy-1-phenyl.

8. A Mn(II) carboxylate complex according to Claim 1 or 2, in which Y is (C_1-20) lower alkylene, optionally selected from dimethylene,

trimethylene, tetramethylene, pentamethylene and hexamethylene; p is 2; and m and q are each 0.

9. A Mn(II) carboxylate complex according to Claim 1 or 2, in which Y is lower (C_2-10) alkenyl

substituted by halogen, hydroxyl, lower (C_1-20) alkoxy, nitro, a substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated carbocyclic ring system, a substituted or

unsubstituted mono-, bi- or polycyclic aromatic hydrocarbon or a substituted or unsubstituted mono-, bi- or polycyclic saturated or unsaturated heterocyclic ring system.

10. A Mn(II) carboxylate complex according to Claim 9, in which Y is a lower (C_2-10) alkenyl, optionally acrylyl, substituted by a heterocyclic ring system, preferably imidazol-4-yl.

11. A Mn(II) carboxylate complex according to any one of the preceding claims, in which the complex additionally comprises at least one oxygen donor ligand optionally selected from water, hydronium ions and lower (C_1-20) alkanols, preferably ethanol.

12. A Mn(II) carboxylate complex according to any one of the preceding claims, the complex additionally comprising at least one nitrogen donor ligand selected from substituted or unsubstituted

saturated or unsaturated ring nitrogen-containing mono-, bi-, or polycyclic ring systems, ammonia, substituted or unsubstituted primary, secondary or tertiary amines or bi- or polycyclic fused ring systems.

13. A Mn(II) carboxylate complex according to Claim 12, in which the nitrogen donor ligand is selected from the group comprising substituted or

unsubstituted pyridine, 1,10-phenanthroline and 2,2'-bipyridine.

14. A Mn(II) carboxylate complex according to any one of preceding claims, the complex being selected from the list comprising:

Mn(oda).H₂O;

[Mn₂(oda)(phen)₄(H₂O)₂] [Mn₂(oda)₃(phen)₄].4H₂O;

[Mn₂(salH)₄(H₂O)₄];

[{Mn₂(sal)₂(salH)(H₂O)(H₃O)(py)₄.2py}_n];

[{Mn(salH)₂(bipy)(H₂O)}_n];

[Mn(salH)₂(phen)];

[Mn(nda)(H₂O)];

[Mn(η¹η¹-nda)(phen)₂].EtOH.H₂O;

[Mn(bdoa)(H₂O)₃];

[Mn(bdoa)(phen)₂(H₂O)];

[Mn(bnda)(H₂O)₃];

[Mn(bnda) (phen)₂(H₂O)₂];

[Mn(bda)(H₂O)₂]; and

[Mn(E-uro)₂(H₂O)₄]

in which n is ≥ 1.

15. A process for the preparation of a Mn(II)

carboxylate complex according to any one of Claims 1-11, which process comprises reacting a Mn(II) salt of the formula

Mn(II)L in which L is a leaving group which may optionally be selected from acetate and halogen, preferably chloride, with an appropriate carboxylic acid, or a salt thereof, in a suitable reaction medium, preferably selected from water and an

ethanol:water mixture, more preferably a 4:1 (v:v) ethanol:water mixture, to obtain the Mn(II) carboxylate complex.

16. A process for the preparation of a Mn(II)

carboxylate complex according to Claim 12 or 13, which process comprises:

(i) (a) reacting a Mn(II) salt of the formula

Mn(II)L

in which L is a leaving group which may optionally be selected from acetate and halogen, preferably chloride, with an appropriate carboxylic acid, or a salt thereof, in a suitable reaction medium, preferably selected from water and an

ethanol:water mixture, more preferably a

4 :1 (v:v) ethanol:water mixture, to obtain the

Mn(II) carboxylate complex according to any one of Claims 1-11; and

(i) (b) reacting the Mn(II) carboxylate complex with an appropriate nitrogen donor ligand to obtain the Mn(II) carboxylate complex according to Claim 12 or 13; or (ii) reacting a Mn(II) salt of the formula Mn(II)L

ethanol:water mixture, more preferably a

4 : 1 (v:v) ethanol: water mixture, the reaction medium also containing an appropriate nitrogen donor ligand, to obtain the Mn(II) carboxylate complex according to Claim 12 or 13.

17. A catalyst for accelerating disproportionation of hydrogen peroxide, hydrogen peroxide-liberating percompounds and hydrogen peroxide-generating percompounds, the catalyst comprising a Mn(II) carboxylate complex according to any one of Claims 1-14.

18. Use of a Mn(II) carboxylate complex according to any one of Claims 1-14 as a disproportionation catalyst.