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J . CHLM SOC. DALTON TRANS. 1995 3565Preparation and Crystal Structures of the Silver(i)Graham Smith,*Pa Adi N. Reddy,a Karl A. Byrielb and Colin H. L. Kennardba School of Chemistry, Queensland University of Technology, PO Box 2434, Brisbane, 4001, AustraliaDepartment of Chemistry, The University of Queensland, Brisbane, 4072, AustraliaTwo silver ammine complexes with the polyprotic aromatic acids benzene-I ,2-diacarboxylic acid(phthalic acid) and benzene-I ,3.5-tricarboxylic acid (trimesic acid) have been prepared and theirstructures determined using single-crystal X-ray diffraction and infrared spectroscopy. Complex 1,[Ag,(C,H,(CO,),}( NH,),], is a hydrogen-bonded polymer based on a simple diamminephthalatodi-silver(i) species, with an ammonia molecule and a single phthalate carboxylate oxygen bonded toseparate silver atoms, giving essentially linear co-ordination [Ag-N 2.1 16(3), Ag-0 2.1 34(2) A,0-Ag-N 175.3(1 )"I.All three ammine hydrogens are involved in intermolecular hydrogen-bondinginteractions, giving a chain polymer. Complex 2, [NH,] [Ag,(C,H,(CO,),},(NH,),( H,O),]~H,O, is atwo-dimensional sheet polymer based o n a pseudo-centrosymmetric S-type trimer unit, linked by thecarboxylate groups of two independent trimesate residues [Ag Ag 2.928( 1 ), 2.946(1) A]. The twoammonia molecules are also bonded linearly to two independent silvers [Ag-N 2.1 41 (6). 2.1 59(7) A;N-Ag-0 166.1 (2), 170.2(2)"]. The terminal silvers provide bonding links to adjacent trimesatecarboxyl oxygens between the layers while the third trimesate carboxyl group forms conventionalcentrosymmetric bis[(carboxylato-O,O')silver(~)] dimers [Ag Ag 2.847(1), 2.856(4) A], withwater molecules in the axial sites for the dimer.A third compound 3, ammoniumsilver( I) pyrazine-2,3-dicarboxylate [NH,] [Ag(C,H,N,(CO,),}], has also been prepared usinga procedure similar to that for 1 and 2. However, unlike them, it has no bondedammines but has a distorted trigonal-planar co-ordination involving two carboxylate oxygens[Ag-0 2.333(6), 2.376(5) A] and one heteronitrogen [AS-N 2.249(6) A], from three separateligand molecules, giving a polymer structure.The diamminesilver(r) ion represents a classical archetypalsilver structure, with the textbook linear stereochemistry arisingfrom sp hybridization about silver.The early crystal structuredetermination of [Ag(NH,),],SO, by Corey and Wyckoffconfirmed the presence of discrete cations and anions in thesolid state; this linear cationic species was also being found inthe structures of [Ag(NH3),]N033 {and the isomorphous(NO,),] ' and in a number of other silver ammine complexes.With the determination of the crystal structures of an increasingnumber of silver complexes, particularly of those withcarboxylic acids, of which surprisingly few examples wereknown' until work by our group, tetrahedral and trigonalstereochemistries now appear more 'normal' than linear forsilver(1). Our interest in the structural chemistry of silver(1)carboxylates has resulted in the determination of more thanthirty structures and allowed classification of the structuretypes,8 the majority being based on bis(carboxy1ato-0,O')dimers.These dimers may be discrete, such as in silver(1)benzoate or salicylate," or they may be extended in the axialsites of the dimer into tetramers [e.g. silver(1) (6flUOrO-phenoxy)acetate hydrate ' '3 or polymers [silver(I) phenoxy-acetate ''I. Less common is the presence of an oxygen-donor[Ag(NH3),IC1044) 9 [Ag(NH 3)JBF4, CAg(Ni-1,),1CAg-f Silver( I ) Carboxylates. Part 13.Siipplt.rnrnturj, dutu available: see Instructions for Authors, J . Cliem.Soc , Dulton Trms., 1995, Issue 1 , pp. xxv-xxx.group of a smaller molecule such as a water [silver(r) N -acetylanthranilate hydrate ''1 or a perchlorate [silver(I) (2-ch1orophenoxy)acetate-silver(1) perchlorate ''1 in these sites.Open structures are also found, having essentially linear two-co-ordinate silvers [e.g.silver(1) (4-chloro-2-methy1phenoxy)-acetate l 3 (zigzag chain polymer), silver(1) fumarate (figure-of-eight ring polymer) and silver(1) nicotinate '' (helical chainpolymer). In these the co-ordination about silver is either linearor trigonal planar.The preparation of silver carboxylates under aqueousconditions often results in the formation of very insoluble 'silversalts', for which crystal-structure determination is difficult,requiring special conditions for crystal growth, e.g. gelpermeation (silver succinate 14). With other cases in which thesilver salt is moderately water soluble, e.g.silver(r) hydrogen( + )-tartrate monohydrate, solubility is enhanced by thehydrophilic nature of the acid and the product is atypical, with astructure more closely related to those of the Group 1 metal( + )-tartrates and hydrogen ( + )-tartrates (distorted-octahedralsix-co-ordinate, with no carboxylato-0,O' links). The use ofammoniacal conditions to enhance the solubility of the silvercarboxylates has been the preferred method employed by ourgroup for preparing crystalline products for X-ray analysis.Under these conditions most silver(1) complexes involvingmonocarboxylic acids result in the incorporation of noammonium ion, exceptions being ammonium silver(1) nicotinatemonohydrate ' and ammonium silver(1) N-acetylanthranilatedihydrate.However, polycarboxylic acids, because of th3566 J. CHEM. SOC. DALTON TRANS. 1995steric constraints imposed on the crystallizing system by themultiple functional groups, show a greater tendency, even inthe presence of an excess of silver ions, to incorporate anammonium counter ion, e.g. ammonium silver(1) citrate (3-carboxy-3-hydroxypentane-l,5-dioate) monohydrate. l 6 Theseconstraints are more acute when an aromatic acid such asphthalic acid (benzene- 1,2-dicarboxylic acid) or trimesic acid(benzene- 1,3,5-tricarboxylic acid) is used. The preparation ofthe silver salts of both of these acids under ammoniacalconditions gave products with an elemental analysis (C, H, N)indicative of an unusual stoichiometry, consistent with thepresence of ammine substitution in the complexes [Ag,(C,-(NH,),(H,O),]-H,O 2.The infrared spectrum for 2 wasnot conclusive enough to confirm the presence of co-ordinatedammine (because of interfering frequencies due to theammonium ion, water and carboxylates in the criticalinterpretative regions). However, that of 1 and both the crystalstructure determinations and chemical analyses for 1 and 2enabled the confirmation of the presence of co-ordinatedammine in both, representing the first structural evidence forthis phenomenon in silver(r) carboxylates. Also reported is thecrystal structure of the silver complex with a dicarboxylic acidanalogous to phthalic acid, ammonium silver(r) pyrazine-2,3-dicarboxylate [NH,][Ag(C,H,N,(CO,),}] 3, in which noammine incorporation is found.'4(CO2)2I(NH3)2I and [NH41[Ag,(C6H3(C0,)3),-ExperimentalPreparation.-Compound 2 was prepared using a previouslydescribed procedure by interacting 1 : 3 stoichiometricamounts of benzene-l,3,5-tricarboxylic acid (trimesic acid)(0.21 g, 1 mmol) and silver nitrate (0.51 g, 3 mmol) in a totalvolume of ca. 30 cm3 of 10% aqueous ammonia solution.Compound 1 was prepared using a similar procedure exceptthat potassium hydrogenphthalate (0.20 g, 1 mmol) was usedinstead of phthalic acid, with AgNO, (0.34 g, 2 mmol), ina total volume of cn. 30 cm3 of 10% ammonia solution.Allowing the solutions partially to evaporate at room temper-ature in the dark over several weeks gave large colourlessneedle prisms of 1 (0.30 g, 75% yield) and flattened prismsof 2 (0.45 g, 42% yield) (Found: C, 23.1; H, 2.4; N, 6.6.Calc.for C,HIoAg2N20, 1: C, 23.2; H. 2.4; N, 6.8. Found: C,20.2; H, 2.1; N, 3.9. Calc. for C1,H,,Ag,N3Ol5 2: C, 20.7;H, 2.1; N, 4.0%). Compound 3 was prepared in a similarmanner to that of 1 by using 1 : 2 stoichiometric amounts ofpyrazine-2,3-dicarboxylic acid (0.14 g, 1 mmol) and silvernitrate (0.34 g, 2 mmol) in a total volume of 20 cm3 of10% aqueous ammonia solution. Yellow crystals began to formfrom the colourless solution after standing for 3 d (0.25 g,86% yield). These crystals were hard, chemically stable andrelatively photoinsensitive (Found: C, 23.9; H, 2.0; N, 14.1.specimens used for X-ray analysis were cleaved from largercrystals. Infrared spectra were completed on all samples asrapidly pressed discs in KBr, using a Perkin-Elmer 1600 seriesFTIR spectrometer.Calc.for C6H6AgN30,: c , 24.7; H, 2.0; N, 14.4%). AllCrystallography.-Crystal data. C,H,,Ag,N,O, 1, M , =413.9, monoclinic, space group C2/c, a = 12.108(1), b =8.143(1), c = 11.942(1) A, p = 115.394(5)", U = 1063.7(2) A3,Z = 4, D, = 2.585, D, = 2.60 g ~ m - ~ , F(OO0) = 792, h =0.710 73 A, p(Mo-Ka) = 36.8 cm-', T = 298(2) K.C18H2,Ag5N3015 2, M , = 1059.7, monoclinic, space groupP2,/n, a = 7.236(3), b = 16.897(3), c = 20.52(1) A, p =99.62(2)", U = 2474(2) A3, 2 = 4, D, = 2.846, D , = 2.83 g~ m - ~ , F(OO0) = 2024, h = 0.710 73 I$, p(Mo-Ka) = 39.7 cm-',T = 298(2) K.C6H,AgN304 3, M , = 292.0, triclinic, space group pi, a =6.838(4), b = 7.885(2), c = 8.072(7) A, a = 84.54(4), p =69.65(6), y = 80.34(4)", U = 402.2(4) A3, Z = 2, D, = 2.41 1,D, = 2.40gcm 3 , F(OO0) = 284,h = 0.710 73&p(Mo-K~) =25.0cm ', T = 298(2) K.Data collection, structure solution and rejnerzzent.X-Raydiffraction data were collected from crystals measuring0.25 x 0.18 x 0.15 (I), 0.25 x 0.20 x 0.12 (2) and0.42 x 0.20 x 0.18 mm (3) on an Enraf-Nonius CAD-4diffractometer, using graphite-crystal monochromatized Mo-Ka radiation. Of 939 (l), 4716 (2) and 141 1 (3) uniquereflections collected up to 20,,, = 50°, 877 (l), 4349 (2) and1221 (3) with F, > 4.00(F0) were considered observed and usedin the expression of the unweighted refinement residuals;(FoZ)]*},, with w = [02F02 + (AP)2 + BPI, where P =[max(Fo , 0) + 2FC2]/3.Collection ranges were: for 1, 11 0-14,k 0-9, I - 14 to 12; for 2, h 0-8, k 0-19, I -24 to 24; for 3, h 0-8,k - 9 to 9, I - 8 to 9. The data were corrected for absorptionusing empirical methods (MOLEN "). The structures weresolved using the Patterson procedure of SHELXS 8618 andrefined by full-matrix least squares (SHELXL 93 1 9 ) to residualsR1, wR2andSof0.025,0.089,0.61 (1),0.092,0.33, l.lO(2)and0.055, 0.138, 1.07 (3) respectively. For 1, A = 0.150, B = 2.55;for 2, A = 0.0293, B = 4.9 and for 3, A = 0.106, B = 0.0.Number of parameters: 94 (l), 458 (2) and 152 (3). Remainingelectron-density peaks: 0.476, - 0.648 (1); 0.549, - 0.607 (2);and 1.524, - 2.095 e k3 (3). For all compounds hydrogen atomswere located by difference methods and included in therespective refinements with both positional and isotropicthermal parameters refined.Atomic coordinates for compounds1-3 are given in Table 1, selected bond distances and angles inTable 2.Additional material available from the Cambridge Crystallo-graphic Data Centre comprises H-atom coordinates, thermalparameters and remaining bond lengths and angles.R l [= C(llF,I - ~Fcl~/~Fol)], wR2 { = [Cw(FO2 - Fc2)2/C~2-Discussion[Ag,{C,H4(C0,)2}(NH3)2] 1.-In the structure of diam-minesilver(r) phthalate the 'outer' oxygen of each phthalatecarboxyl group is bonded to a silver ion [Ag( 1)-O( 12) 2.134(2)A] (Fig. 1). These complex units have molecular symmetrycoincident with crystallographically imposed two-fold rota-tional symmetry.In the sites trans to these oxygens are foundthe ammine groups [Ag( 1 )-N( I) 2.1 16(3) A, N( 1)-Ag( 1 )-O( 12)175.3(1)"]. This Ag-N value compares with 2.110(3) 8, indiamminesilver(1) perchlorate and 2.15( 3) A in diammine-silver(1) tetrahydroborate.5 The Ag-O(carboxy1) distancecompares with typical values of 2.18-2.20 A in the bis(carb-oxylato-0,O') dimer lo and 2.19-2.22 A in the open carboxyl-bridged polymer structures.' An unusual feature of the presentstructure is the presence of parallel associations between the9 PFig. 1 Molecular structure and atom numbering scheme forCAg,(C,H,(C02)2)(NHJ),1 J . CHEM. SOC. DALTON TRANS. 1995 3567linear 0-Ag-N bonds across inversion centres in the cell.These have silver-silver separations [Ag( 1) Ag( la)] of3.244(1) 8, (a - x, i - I), 1 - :), with hydrogen bondingbetween all three ammine hydrogens, and the carboxyloxygens [N( 1)-H(3 1) O( 12a) 3.089(4) A, N-H 0 160";N(l)-H(13)-.*0(13~) 3.108(4) A, N-H.s.0 157" (C i + X ,Fig.2 Packing of complex 1 in the unit cell showing hydrogen-bonding associations. The view is down the phthalate rings with all ringcarbons except C( 1) and C( 1 b) omitted for clarity$ + y , 2); N(1)-H(1 1) O(13d) 2.994(4) A, N-H 0 174"(d 1 - x, 1 - y , 1 - z)]. This results in a two-dimensionalhydrogen-bonded sheet structure which extends across the bcdirection of the cell (Fig. 2). The hydrogen bonds also formlinks between the sheets via the unco-ordinated carboxyloxygens.The phthalate residues are similar to that found in thestructure of the parent acid,20 with the carboxylate groups lyingconsiderably out of the plane of the benzene ring [torsion angle0(12)-C(1 l)-C(l)-C(2) -47.4(2)", cf -32.7" in the parent]."H4ICAg5 (C6H3(C02)3 } 2(NH3)2(H20)21*H2O 2*--Thepolymeric layer structure has at its centre a unique open S-typestructural unit (Fig. 3), comprising three silver atoms [Ag(l),Ag(3) and Ag(2)] linked by carboxylato-O,O' bridges from thetwo trimesate residues [Ag(l)-O(322) 2.183(4), Ag(3)-0(332f)2.107(4), Ag(2)-O(321) 2.165(4), Ag(3)-0(331a) 2.105(5) A].This gives Ag( 1) A (3) and Ag(2) Ag(3) separations of2.928( 1) and 2.946( 1) 1 respectively, while the 0-Ag-0 bondangle at the pseudo-inversion centre [Ag(3)] is 178.5(2)".In thesites ~rans to the outer carboxyl oxygens are the two amminegroups, giving a bonding mode similar to that of complex 1. TheAg( 1)-N(3) and Ag(2)-N(2) distances are 2.141(6) and 2.1 59(7)Fig. 3the a axis of the unit cellMolecular configuration, atom numbering scheme and packing mode for [NH,][Ag,{C,H,(C0,)3}z(NH3)2(H,0)z]~H20 2 viewed dow3568 J . CHEM. SOC. DALTON TRANS. 1995k3117(1)2776( 3)4678(2)4366(3)910(3)3956( 3)2562( 3)288(3)242( 3)- 259325)- 2446( 26)- 1974(23)- 1584(25)- 1686(25)-2216(25)- 3203 26)3 1 65( 29)- 1252( 24)- 36 1 2( 20)- 33 1 3( 22)3504(27)291 l(23)- 1105(21)- 1124(21)33 1 5( 24)1332( 1 )2864(9)2282( 10)l901( 10)2203(8)2821( 1 1 )31 17( 1 I )I'3359( 1)54 19( 3)- 5 12(3)- 2003(4)5576( 1)4328( 1 )4961(1)9462( I )5568( 1 )6694( 10)7461(10)8067( 10)7909( 10)7131(11)6530( 10)6063( 1 I )6100(11)6914(10)5387( 8)6259(9)5546( 8)6019(8)6 189( 7)7464( 8)7006( 10)7917( I )3877( 7)5569(9)67 1 3 8 )6178(7)45 1 6( 9)3352(9)4181(1)5067( 3)2870(2)321 9(3)1143( I )- 1127(1)37( I )5 4 3 1 )5524( 1 )3834(9)4066( 9)3674( 8)3043 8)281 l(9)3229(9)4272(9)- 1061(9)2138(8)4022( 6)4856(6)- 1435(8)- 466( 7)2015(6)1730(6)2764( 9)6732( 1 )I779( 8)1560(9)2888(9)4424( 7)461 1( 10)3309( 10)\4679( 3)4412(2)3344( 2)5225( 2)3402(26)3039(25)2576(25)241 7( 27)2792(22)367 1 (24)1 808( 26)1 764( 27)3668(23)3862( 2 1 )1292(23)2185(24)133 l(20)1726( 22)- 259( 28)4277(27)571(28)- 4422( 26)1083 24)3337( 24)2077( 10)245 1 (9)1573(9)1077(11)2394(8)3163( 10)- 886(8)1'- 3477( 3 )1058(4)1 179( 3)2091(3)7784( 10)7987( 1 1 )7389( 1 I )6599( 10)6420( 1 1 )6790( 1 1 )3826( 10)5982 10)7323 8)6054( 8)4358( 7)3917(8)5337(7)6191(9)4758( 10)3214( 1 I )6694( 1 I )4752( 10)6443 9)3826( 10)6 I29( 9)501 6(7)7735(6)8631(9)9655(6)9028(6)1393 9)2860( 3)3367(2)33 I O( 3)3839( 2)2978( 8)3613(8)4009(9)379 1 (8)3 I83(9)2085(9)1 I33( 8)4228(8)I 660( 7)1964( 7)1508( 7)568(7)3993(6)4828( 7)2644(9)635( 9)2770(8)6486( 7)3433(8)-591(8)- 228(9)- 1351(7)- 4437)2798( 9)2390( 8)331 5(7)8957(9)Table 2 Selected bond distances (A) and angles (") for complexes 1-3Complex 1A&( 1 )-O( 1 2) 2.134(2) Ag(l)-N(I) 2.1 16(3)Complex 2Ag( 1)-O(322)Ag( 1 )-N(3)Ag(2)-N(2)A&( 1 )-O( 1 32)A&(2)-0( 32 1 )Ag(2)-0(521)Ag(2)-0( 132)Ag( 3)-O( 33 1 )Ag(3)-0(332)Ag(4)-0( I 2 1 )2.183(4)2.141(6)2.60 1 (4)2.165(4)2.660( 4)2.59 1 (4)2.103 5 )2.107(4)2.253( 4)2.159(7)2.21 3 4 )2.433 6)2.190(4)2.222(4)2.436(6)2.928( 1 )2.946( 1 )2.847( 1 )2.856(4)Complex 3Ag( 1 )-N(4) 2.249( 6) Ag( I )-O( 32b) 2.376( 5 )Ag( 1)-0(22a) 2.333 6)Complex IO( 12)-Ag( 1 )-N( 1 )Complex 20(322)-Ag( 1 )-N(3)0(322)-Ag( 1)-O( 132)N( 3)-Ag( 1 )-O( 132)O( 32 1 )-Ag( 3)-N( 2)O( 32 I )-Ag(2)-0( 52 1 )O( 32 1 )-Ag( 2)-O( 132)N(2)-Ag(2)-0(521)N(2)-Ag(2)-0( 132)Complex 3N( 4)-Ag( 1 )-O( 32a)N(4)-Ag( 1 )-O( 32b)175.3( 1 )170.2(2)91.7(2)93.9(3)166.1(2)92.9(2)97.8(2)93.9(2)93.9( 3)137.4(2)127.6(2)Symmetry relations: for complex 2, a -.\-.1 - 1'. 1 - 3; b - s. 1 - 1'. - : for 3, a X, J', 1 + z; b -.s, 2 - J,. 10(521)-Ag(2)-0( 132)O(331 )-Ag(3)-0(332)O( 1 2 1 )-Ag( 4)-O( 1 3 1 )O( 1 2 1 )-A&( 4)-O( 30)O( 1 3 1 )-Ag( 4)-O( 30)O( 532)-Ag(5)-0(522b)O( 532)-Ag( 5)-O( 20)O( 522b)-Ag(5)-0(20)87.3( 6)178.5(2)163.4( 2 )97.7(2)98.7(2)164.4(2)99.0(2)96.6(2)0(22a)-Ag( 1 )-O(32b) 92.3(2)A [cf 2.1 16(3) A in 11, with close to linear O-Ag-N angles Ag-O-Ag 90.9(2)'].The Ag( 1 ) . - Ag(2) separation (1 + .Y, J*.[170.2(2) and 166.1(2)" respectively]. The outer pseudo- z ) is 3.517(2) A. Hydrogen bonding stabilizes the structure, viainversion-related silvers [Ag( 1 ) and Ag(2)] are also bonded to a interactions between the ammine group and the unco-ordinatedsingle oxygen [0( 132)] of the carboxyl group of the second carboxyl oxygen of the second trimesate [O( 122) N(3) 3.00,trimesate residue giving layers down the short (u) crystallo- O( 122) - - - N(2) 2.99 A]. The third carboxylate group of eachgraphic axis [Ag(l)-O(l32) 2.610(4), Ag(2)-0( 132) 2.591(4) A, trimesate is involved in co-ordination to the fourth and fiftJ . CHEM. SOC. DALTON TRANS. 1995 3569.Fig. 4 Molecular structure and atom numbering scheme for [NH,][Ag(C,H2N,(C0,),)1 3silvers [Ag(4)-O( 121) 2.253(4), Ag(4)-0(131d) 2.215(4) (d -x,2 - .v, -z); Ag(5)-0(522e)2.222(4),Ag(5)-0(532)2.190(4)A(eI - x, -13, -z) via two centrosymmetric bis(carboxy1ato-0,O') dimers.These dimers have inversion symmetry, similar toa large number of silver(1) carboxylates [Ag(4) Ag(4a)2.847(1) (a -x, 1 - y , 1 - z ) ; Ag(5) 0 . Ag(5b) 2.856(1) 8,(b -s, 1 - y, -:)I. In the terminal sites of these dimers arefound water molecules, such as is in silver N-acetylanthranilatedihydrate [Ag(4)-O(30) 2.435(6), Ag(5)-O(20) 2.436(6) A],giving Type 2 dimers8 These waters are also hydrogen bondedto the free carboxylate groups [0(20) O(122) 2.78 A] and tothe ammonium ion [0(20) - - N( 1) 2.83 A].The ammonium ionand the lattice water [O(lO)] are involved in a number ofadditional hydrogen-bonding interactions with carboxylateoxygens.[NH,][Ag{ C,H,N,(CO,),)] 3.-The structure of ammo-nium silver(r) pyrazine-2,3-dicarboxylate 3 forms a ribbonpolymer based on distorted trigonal-planar three-co-ordinatesilver centres. These involve one bond to a pyrazine nitrogen[Ag( 1)-N(4) 2.249(6) A] and two bonds to symmetry-relatedcarboxylate oxygens [Ag(l)-0(22a) 2.333(6) A (a x, y , 1 + 2);Ag(l)-0(32b) 2.376(5) 8, (b -x, 2 - y , 1 - z ) (Fig. 4). Thesecond carboxyl oxygens of each group also give weaker asym-metric bidentate associations with silver [Ag-O(21 a) 2.821(6),Ag-O(3lb) 2.825(6) A]. This co-ordination mode is similar tothat found in ammonium silver(1) nicotinate monohydrate l 2except that the trigonal centres in 3 are of the AgOzN typerather than AgON,.Furthermore the presence of the twocarboxylate groups results in open centrosymmetric 14-membered rings which accommodate the ammonium ionsthrough association. The pyrazine rings comprising the 'ends'are offset by half the cell parameter down the a-cell direction,which probably contributes to the yellow colour observed forthis compound. A number of hydrogen-bonding associationsare found between the ammonium ion "(lo)] and bothpyrazine nitrogens and carboxylate oxygens, within andbetween the ribbons [within N( 10) - - . N( 1) 3.05,N(1O) O(21) 2.82; between N(10) O(31) 2.91,2.86 A].The carboxylate groups adopt different conformations, onebeing almost coplanar with the pyrazine ring, the other almostperpendicular [torsion angles N( 1 )-C(2)-C(21 )-O(21) 0.03,N(4)-C(3)-C(31)-0(31) 82.5" respectively].This contrastswith the parent acid where both are equal and inclined( 145.4"). "N(10)**-0(31) 2.85, N(10)***0(22) 3.20, N(10)***0(32)Infrared Spectroscopy.-The use of infrared spectroscopy toidentify the presence of co-ordinated ammine molecules insilver carboxylate complexes presents difficulties, not only withrespect to sample preparation (as pressed KBr discs) but also inthe occurrence of the fundamental vibrational frequencies in theregions of the spectrum where both carboxylate and aromaticring vibrations are found. This problem is made insoluble whereammonium ions and both co-ordinated and lattice waters arepresent, as in the case of the trimesate complex 2.Identificationin this case is based on the crystal structure and on elementalanalysis. However, with the anhydrous silver ammine phthalatestructure 1 (in the absence of both NH4+ and H20), the broadabsorption band (3425 cm-') can be due only to ammoni3570 J. CHEM. SOC. DALTON TRANS. 1995which, together with the presence of a weak v(Ag-N)absorption at 424 cm-' is consistent with silver-ammineco-ordination. This latter value compares with the 400 cm-lfound for symmetrical silver(r) ammines, e.g. [Ag(NH3)J2-S04,22 and represents a shift to higher frequency consistentwith the presence of three hydrogen-bonding associationsinvolving the ammonia.The NH, deformation frequency isalso recognized as a partially resolved peak at cu. 1610 cm-'while the aromatic frequencies do not allow identification ofthe pr(NH,) frequency in the region 600-750 cm I . The mag-nitude of the splitting parameter A for the carboxyl v(C-0)frequencies (1560 and 1384 cm-' respectively) is 176 cm-'which is similar to the values found for both ionic acetate (164cm-1)23 and bridging acetate [as distinct from the smallervalues for chelating (bidentate) acetate 24]. With the trimesatecomplex 2, in which both bridging and unidentate carboxylatesare found, the value of A cannot be determined with anycertainty.With complexes 1 and 2 the phenomenon of formation ofmixed carboxylate-ammine co-ordination complexes withsilver(1) under similar preparative conditions, whilst it has noprecedent in the chemical literature, it is not unexpected.Thesteric constraints imposed by the aromatic ring systems on thecarboxylic acid groups in both 1 and 2 make it difficult toinvolve all of these in conventional bis(carboxylat0-0,O')silver(1) dimer associations. Therefore, the ammonia moleculesact in a space-filling capacity, occupying the sites trans to thecarboxyl oxygen. No known examples exist where a watermolecule occupies the trans site to the carboxylate oxygen insilver carboxylates, the water invariably occupying the axialdimer sites. In such examples, this bond is considerablyelongated [e.g. 2.52 cf 2.13 A for the Ag-0 (carboxyl)bond in complex 13.AcknowledgementsThe authors acknowledge financial support from the Centrefor Instrumental and Developmental Chemistry of theQueensland University of Technology, the AustralianResearch Council and the University of Queensland.References1 Part 12, G.Smith, D. S. Sagatys, C. Dahlgren, D. E. Lynch,R. C. Bott, K. A. Byriel and C. H. L. Kennard, 2. Kristallogr.,1995,210,44.2 R. B. Corey and R. W. G. Wyckoff, Z. Kristullogr., 1934,87, 264.3 T. Yamaguchi and 0. Lindqvist, Acta Chem. Scand., Ser. A , 1983,4 U. Zachwieja and H. Jacobs, Z. Kristallogr., 1992, 201, 207.5 U. Zachwieja, Thesis, Universitat Dortmund, 1991.6 H. M. Maurer and A. Weiss, 2. Kristallogr., 1977, 146, 227.7 C. A. McAuliffe, in Comprehensive Coordination Chemistry, ed.G.A. Wilkinson, Pergamon, New York, 1987, vol. 3, p. 21 I .8 T. C. W. Mak, W.-H. Yip, C. H. L. Kennard, G. Smith andE. J. O'Reilly, Aust. J. C'hem., 1986, 39, 541.9 I. R. Amiraslanov, B. T. Usubaliev, G. N. Nadzhafov, A. A.Musaev, M. Movsumov and Kh. S. Mamedov, J. Struct. Chem.(USSR), 1981,22,653.10 G. Smith, C. H. L. Kennard andT. C. W. Mak, Z. Kristallogr., 1988,184,275.11 G. Smith, D. S. Sagatys, C. A. Campbell, D. E. Lynch and C. H. L.Kennard, Aust. J. Chem., 1990,43, 1707.12 G. Smith, A. N. Reddy, K. A. Byriel and C. H. L. Kennard,Polyhedron, 1994, 13, 2425.13 T. C. W. Mak, W.-H. Yip, C. H. L. Kennard, G. Smith andE. J. O'Reilly, J. Chem. Soc., Dalton Trans., 1988, 2353.14 A. Michaelides, V. Kiritsis, S. Skoulika and A. Aubry, Angew.Chem., Int. Ed. Engl., 1993, 32, 1495.15 R. C. Bott, G. Smith, D. S. Sagatys, D. E. Lynch and A. N. Reddy,Z. Kristallogr., 1994, 209, 803.16 D. S. Sagatys, G . Smith, R. C. Bott, D. E. Lynch and C. H. L.Kennard, Polyhedron, 1993,12,709.17 C. K. Fair, MOLEN, An Interactive Intelligent System for CrystalStructure Analysis, Enraf-Nonius, Delft, 1990.18 G. M. Sheldrick, SHELXS 86, Program for the Solution of CrystalStructures, University of Gottingen, 1986.19 G. M. Sheldrick, SHELXL 93, Program for Crystal StructureDetermination, University of Gottingen, 1993.20 W. Nowacki and H. Jaggi, Z. Kristallogr., 1957, 109,272.21 F. Takasagawa and A. Shimada, Chem. Lett., 1973, 1 12 1.22 A. L. Geddes and G. L. Bottger, Inorg. Chem., 1969,8,802.23 K. Itoh and H. J. Bernstein, Can. J. Chem., 1956,34, 170.24 K. Nakamoto, Infrared and Raman Spectra of Inorganic andCoordination Compounds, 4th edn., Wiley, New York, 1986, p. 232.Received 4th July 1995; Paper 510433 1 J34,685

ISSN:1477-9226    

DOI:10.1039/DT9950003565

出版商:RSC    

年代:1995

数据来源: RSC