A spectroscopic study on the cobalt(II), nickel(II) and copper(II) complex salts and the mono- and di-sodium salts of sulphamide

Spectmchimica Acta.Vol. 35A.pp.439to 442 0 Peremon PressLtd., 1979. Printed in Great Britain

A spectroscopic study on the cobalt(II), nickel(I1) and copper(I1) complex salts and the mono- and di-sodium salts of sulphamide GIORGIO

PEYRONEL* and ALEARWGIUSTI

Istituto di Chimica Generale e Inorganica, University of Modena, 41100 Modena, Italy (Received 15 June 1978) Abstrac-The sulphamide (H&Q complex salts Co(HSuh.H,O, NiSu-MeOH.HzOand CuSu.MeOH were preparedfrom basic solutions. The cobalt complex has a pseudo-tetrahedralcoordination with C,, symmetry: the nickel complex has presumably a polymeric constitution with one paramagnetic octahedral and one diamagnetic planar chromophore. The i.r. spectfa (4OOO&cm-‘) of the complexes are discussed by comparison with the spectra of H,Su, NaHSu. Na2Su and of rhodium(III)and mercury(II)-Su complex salts reported in the literature. In C~(HSU)~.H~O the coordination of the HSu- anion occurs only through its oxygen atoms. In NiSu*MeOH*H20 and CuSu.MeOH the coordination of the Su’ anion involves both its oxygen and nitrogen atoms. INTRODUCTION

(H2N-S02-NH2 = H&) is capable of acting as a proton donor even in aqueous solution 111. The di-sodium and potassium salts MzSu may be prepared from HzSu and the corresponding amides MNHz in liquid ammonia [II, the mono-sodium and potassium salts MHSu from the ethoxides MOEt in absolute ethanol and LiHSu from LiOH in aqueous solution [2]. The silver salt Ag,Su was prepared [3] and the complex salt Na[Rh(Su)AH20)21 143 was studied by comparison of its i.r. spectrum (4000-300 cm-‘) [51 with that of the neutral sulphamide. Also the i.r. spectra of three undefined insoluble sulphamide precipitates of mercury(I1) have been partially investigated by i.r. spectra in the 4000-7OOcm-’ region[6]. The sulphamide complex salts of cobalt(H), nickel(H) and copper(I1) have been prepared and their i.r. spectra (4000-6Ocm-‘) studied by comparison with those of sulphamide and its mono- and di-sodium salts, whose anions are the ligands of the complex salts.

Sulphamide

EXPRRIMRNTAL Sulphamide (Fluka) and the other reagents used were of the best chemical grade. The NaHSu salt (analysis: found % (calcd. %): N 23.79 (23.72). H 2.63(2.56)) was prepared by the method of TRAUBE 121and the Na#u salt (Analysis: N 19.58(20.00), H l.Xl(1.44)) by the method of Franklin reported in Ref. [l]. The complex salts were prepared by the following methods. Co(HSuk*HzO: a solution of NaOH (2mmol) in methanol was slowly added to a solution of H#u (8mmol) and anhydrous CoC12 (2 mmol) in methanol (10 cm3). Firstly a rose-violet precipitate, containing variable amounts of sulphamide, was formed and was therefore filtered after the addition of one NaOH *Author directed.

to whom

SAA Vol. 35A.No. 5-D

all correspondence

should

be

equivalent to the solution. By adding the second equivalent of NaOH to the filtered solution the compound was obtained in beautiful blue microcrystals, and washed with methanol (Analysis: N 20.8li21.05j, H 2.52(2.65)).

NiSusMeOH-HzO:a solution of (CH&NOH (4mmol) in methanol (1.6 cm’) was slowly added with stirring to a solution of H2Su (4 mmol) and anhydrous NiCl* (2 mmol) in methanol (15 cm’). The precipitate firstly formed dissolved in the mother solution with stirring and, after two equivalent of the base were added to the solution, persisted as a light-green product which was. washed with methanol (Analysis: Ni 29.17 (28.94), S 16.07(15.80), C 6.34(5.92), N 13.96(13.81), H 3.93(3.97)). The same product was obtained by using nickel nitrate and sodium hydroxide. CuSu.MeOH: a solution of (CH,).,NOH (2mmol) in methanol (1.6cm’) was slowly added with stirring to a solution of HzSu (4 mmol) and CuC12.2H,0 (2 mmol) in methanol (20cm’) and the dark-green precipitate was washed with methanol (Analysis: Cu 33.67(33.50), S 16.50(16.90), C 6.99(6.33), N 14.36(14.77), H 3.58(3.19)). The compounds were analysed bv standard methods. The i.r. spectra were recorded on the solids in KBr disks (4000-25Ocm-‘) with a Perkin-Elmer 521 snectronhotometer and ai Nujol mulls on polythene (4&-6O~~m-~) with a Perkin-Elmer 180 spectrophotometer (Table 1). The electronic spectra were recorded on the solids as Nujol mulls on thin glass plates with a Shimadzu MPS50L spectrophotometer. The magnetic susceptibilities were measured at room temperature by the Gouy method and corrected for the Pascal constants.

RESULTS AND DISCUSSION The

electronic

spectrum

(Fig.

1)

of

the

Co(HSu)2*H20 complex clearly indicates a pseudotetrahedral coordination with CzV symmetry, both the v2 and vj bands being split in three distinct maxima [7,8]. The crystal field parameters Dq and B were calculated with the relations given by UNDERHILL et al. [9] and the v, band from the vJv2 ratio [lo] by using the averaged v2 and v3 frequency values (cm-‘) almost corresponding the center of gravity of the total intensity

439

to

as

0. PEYRONELad

440

A. GIIJ~~I

suggested by COTTON et al. [ll]: vI calcd. (cm-‘) 4748

DqBB 7070,8&, 9308 Av. 8110

16180,16~50.18698 Av. 17210

by assuming for Co(I1) a B, value of 971 cm-’ 1121. The Dq, B and /3 values are in the range of other literature values for Co(H) tetrahedral complexes, very close to those of the [COO*] chromophores such as Co(NO& (Dq = 466, B = 755, ~3= 0.78) and Co40(OOCCMe& (Dq = 454, B = 745, B = 0.77) [121. The electronic spectrum of NiSuMeOH.HA and its crystal field parameters [91 are typical for a six coordinated nickel(H) complex 1121: v,(cm-‘) 9480m

0s 253?0 s 926 (Bo = 1041) [12]

15Oiims

B 841

.B 0.81

473

742

0.75

magnetic moment calculated for the stoichiometric unit (2.28 B.&l.) is very low even for a high tetragonal coordination [13] which does not find any support in the electronic spectrum. If the molar susceptivity is related to two stoichiometric units a normal magnetic moment (3.22 B.M.) for a six-coordination is obtained, indicating that the complex may have one paramagnetic octahedral and one diamagnetic planar coordinated nickel atom. The copper(H) complex CuSuMeOH shows a very broad and weak band between 14000 and Its very low magnetic moment 16080 cm-‘. (1.46B.M.) may indicate some metal-metal or superexcliange interactions due to bridging ligand molecules. The principal bands of sulphamide with their assignments given by UNO et al. [14] on the basis of a normal co-ordinate analysis by assuming the molecular symmetry G,,, are reported in Table 1 together with the bands of the salts NaHSu and NazSu and of the Ni(II), Cu(I1) and Co(II)-complexes salts which lie in the same spectral region. For this comparison alsothe bands of the complex NalRh(Su)2(HzOkl [51 and of the insoluble products of variable composition obtained from aqueous solutions of suiphamide and mercuric acetate [6] are considered in the discussion. The r(SO&,,,: v(SO&,, ratio 1166: 1364 = 0.855 for sulphamide is in the range of about 0.81-0.88 observed for several X-SO,Y compounds [IS]. Its

Table 1. Principal i.r. bands (cm-‘) of sulphamide (H$u) and its sodium, nickel(H), copper and cobalt(H) salts. The H&r assignments given by UNO et ai.[14] with their potential energy distributions are reported for the 1460900 cm-’ reaion NiSu MeOH*HzO

cusu MeOH

1342s 120!3msb

12Xlmsb

1288msb 12OOsh

1161s 1115ms 1074m

116Om,sh 112ovs 1065m.sh 975mb 925mb 3%sh

116Osh 1115sb

HsSu

NaHSu

NasSu

v.(So3(71) + ~(NH3(30) + p(So2(5)

1364~s

1348m 1205s

v,(SO&92) + v,(SN88) + S(SO&4)

1166vs

~(NHa69) + v.(So3(31) v.(SNzKlll)+o(S02(9) z&3%.X&I) + v.CXM(~) Ligand bands (400-150 cm-‘)

1132m.sh 934ms

1165ms lllovs 1094sh 1010s 912ms 394s 372s

908s

393m 386sh 358ms 323~ 246wm

v(M-ligand)

22SW

237ms 213ms

161~

176s 155ms

9!XS

908wm 372ms 359nl.s 322wmb 305wmb

975mb (925sh) 370sh

32Osh

324w 3oow

18Ow 157w 279wb 260wb

174mb 155mb 284sb 265sh

‘21 lmsb 2OOmb 176wmb

CdHSuh H20 12lKkb 1252m.sh 1197msb 116Ow.sh 1125vs 108Oms.sh 9%sh 970s 388msb 374sh 358msb 323vw 310w 253wm 214ms 187wb 17ovw 290m 274m

A spectroscopic study on the cobalt(H), nickel@) and copper(I1) This linear relationship has been proposed as a useful test for the location of the v(SOz) frequencies of the X-SOrY compounds [Ml, 171. In the 1400-9OOcm-’ region the NaHSu and Na&u salts show a multiplicity of bands greater than that of H&i, presumably because of a lower symmetry of the anions with respect to the Czu symmetry assumed by UNO et al. [14] for the neutral molecule. The v(SO,) bands, identified by their frequency ratio [16, 17, show a significant frequency decrease only for the v.(S02) bands (- 16 and -22 cm-‘). Similarly, of the bands assignable to u(SN2) modes, only the v.(SN1) bands show a significant frequency increase of +76 and +62 cm-’ for NaHSu and Na2Su, respectively. This behaviour is consistent with a mesomeric shift such as HI&S=0 which decreases the s--O and increases the N-S bond strength. It may be of interest to note the following frequency ratios for these compounds: v, (SO*) v, (SO*) NaHSu 1165 : 1348= 0.864 Na*Su 1161: 1342= 0.865

v. (SNd 1010 : : 1205 = 0.838 996: 1220 = 0.816

v. (SK) 912: 1110 = 0.823 908:1115=0.814 The fact that the v,(SNJ and u,(SN3 bands have, with the two new strong unassigned bands, frequency ratios which are in the range assumed as characteristic for the u,(SO2): u,,(SO2) ratio may tentatively be explained by admitting for the anions a coupling of u(S0) and v(SN) modes. A decrease in the s--O and an increase in the S-N double bond character, by making the force constants of these bonds more similar may be a favourable condition for a mixing together of their bond vibrations [ 181. For the complex salts NiSuMeOH*H20, CuSuMeOH and Co(HSt&.H20 the u,(S02) frequency is lowered to 1280-1288 cm-’ as for the complexes Na[Bh(HSu)2(H20)2] (1300 (m) cm-‘) [5] and the [HgSu], products of variable composition (- 1270(s) cm-‘) [6], indicating for all these complexes that the sulphamide anions are O-bonded to the metal, and consequently the s--O double bond is lowered with respect to the free anions. By applying the frequency-ratio rule, the v,(S02) bands may be identified as follows: u~(so2h(so2)

NiSuMeOH-H20 CuSu*MeOH Co(HSu)2.H20 HWW2(H20)21- 151 [HgSu].(61.4 % Hg) [6]

1120 : 1280 = 0875 1115:1288=0.866 1125 : 1280 = 0.879 1135 : 1300 = 0.873 1127 : 1270 = 0.887

their frequencies being lowered in all these complexes with respect to those of their free anions. For the rhodium(II1) complex this assignment

441

coincides with that given by TORRIBLE[5]. For the mercury(H) salts [6] the bands in the 127& 1127 cm-’ region were generally assigned as (SO,) and (SON) “Valenzfrequenzen” while the bands in the 11OWOO cm-’ region as (SO) and (SN) “Valenzschwingungen”. The u(SN3 frequencies were assigned by TORRIBLE151 as follows: (a) (b)

I-LSu IWHSt&o20)2

u.(SNJ = 1120(s) u.(SN2) = 1200 (m, sh)

(a) (b)

uJSN2) = 935 (m) 960 (in)

900 (m) = unassigned.

As we have tested, the H2Su band registered by this author at 1120 cm-’ on Nujol mulls, corresponds to the band registered by us on the solid in KBr disks at 1132 cm-’ and in Nujol mull at 1130cm-’ by UN0 et al. [14] who assigned it principally to NH2-twisting. The band observed at 12OOcm-’ for the rhodium(II1) complex may correspond to the band observed at 1197 cm-’ for the CO(HSU)YH~O complex, both these complexes containing the same HSu- anion oxygen-coordinated to the metal. As the u(NH) bands of the cobalt complex do not s; v any increase of the NH bond strength, the ban :t 1200 cm-’ may be assigned, better than to the NH2 twisting, to a u(SN,) or @ON) mode. For the rhodium complex a bidentate (0,O) coordinated HSu- anion was admitted on the basis that the observed high u(NH) (3280(m) cm-‘) and @NJ frequencies exclude a N-coordination [5]. For the cobalt(H) complex two (NH) frequencies are observed at 3324(ms) and 326O(sb) cm-’ very close to the H2Su (3338(vs) and 3248 (vs) cm-‘) and HSu- (3332(vs) and 3307 (vs) cm-‘) values, while the lowest frequency (970(s) cm-‘) assignable to a u(SN2) mode and close to the value (96O(m)cm-‘) of the rhodium complex is significantly higher than the u,(SN2) frequency values of all the three forms of sulfamide. A bidentate (0,O)-coordination for the HSu- anion in this complex is therefore quite likely and either in the chelating or in the bridging form it may explain the C2” distorted tetrahedral symmetry as revealed by the electronic spectrum and its crystal field parameters close to those of a [CoOd chromophore. The cobalt complex does not show i.r. bands of coordinated water [19]. It is probably useless to try to assign the other bands owing to the coupling effects which may occur between the v(S0) and v(SN) modes in this spectral region. The NiSu-MeOH-Hz0 and CuSuMeOH complexes have an i.r. spectrum in the 1400-900 cm-’ region rather similar to that of the Su’ anion. Even if the MeOH and H20 molecules participate to the coordination (which is not detectable from the i.r. spectra) it is likely to admit for these complexes, in agreement with their high insolubility, a poly-

G. PEYRONELand A. GIIJSTI

442

merit structure in

which the nitrogen atoms of the anion participate to the coordination as it was already admitted for the [HgSu]. indefinite products [6]. Both the nickel and copper complexes show a very strong band at 3260 and 3230cm-‘, respectively, at frequencies much lower than those of the v(NH) bands (3370(ms) and 3301 (m) cm-‘) of Na*Su. The frequencies of the bands assignable to v,(SN2) and v,,(SNJ modes are, respectively, higher and lower than those of Na&, probably because the (0, N)-coordination of the ligand differently influence the two types of vibrations. The fact that the bands of these complexes in the 1000-900 cm-’ region have frequencies lower than those of the cobalt complex (only oxygen-coordinated) confirms an (0, N)-coordination for these two complexes. In the far i.r. spectra of the nickel, copper and cobalt complexes only two metal-ligand bands could safely be identified in the region of 290260 cm-’ and may be assigned to v(M-0) modes in agreement with other literature values for Co-, Ni- and Cu-0 stretching modes in complexes involving oxo-anions [20-231. Acknowledgment-This work has been supported by a 8nancial aid of the Consiglio Nazionale delle Ricerche (CIUR) of Italy.

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