Inorg. Chem. 1988, 27, 130-137
130
peak arises from the bonding of Pt(I1) to a quadrupole nucleus, n i t r ~ g e n . ~ 'The . ~ ~resonance observed here is comparable to that observed for Pt(4-EtPy)CI3 (6 = -2772 in CH2C12).33 None of the 'H N M R shifts observed here agree with those reported by Theophanidd for R(thiamin)CI,. The chemical shifts cited by these authors for H(6') and H(41') are shifted from those we have observed by 0.2 ppm upfield and 0.6 ppm downfield, respectively. All other thiamin resonances differ by less than 0.1 ppm. However, none are identical. It is possible that the N M R spectrum reported by Theophanides was not acquired on a freshly prepared sample and is, therefore, that of a reaction product of Pt(thiamin)Cl, and the solvent. Our IH N M R results also differ from those reported by A d e y e m ~for~ ~this complex. In fact, Adeyemo's results are more consistent with those we observe for the first main decomposition product resulting from the reaction of Pt(thiamin)CI, with DMSO (see Figure lb). The spectrum shown in Figure l b is that of R(thiamin)CI, after it was allowed to stand in DMSO for 15 min. It shows the proton resonances of the complex and another component in solution, indicative of a possible reaction between the complex and DMSO. The nature of this reaction was elucidated with the acquisition of I9%'t and 'H N M R data along with conductance measurements. Conductance results in DMSO which show that Pt(thiamin)Cl, is a nonconductor are indicative of a nondissociated complex. With time the conductance increases and after several hours, a comparison to other thiamin salts (Table 11) shows that a 1:l electrolyte is present in solution. Two possible reactions, a and b, will
produce compounds that are consistent with these conductance findings. Pt(thiamin)Cl,
+ DMSO
-
(Pt(thiamin)(DMSO)C12)+ Pt(thiamin)CI,
+ DMSO
(thiamin)+
+ C1-
(a)
+ (Pt(DMSO)Cl,)(b)
On the basis only of conductivity data, Theophanides6postulated the reaction a takes place. However, our 19% N M R data provide strong evidence that reaction b, where thiamin has been displaced by DMSO, has occurred. Figure 2 shows two 195Ptresonances observed for a DMSO solution of Pt(thiamin)C13 1 h after mixing: one at 6 = -2896, attributed to Pt(thiamin)C13 and another at 6 = -2965. This latter resonance, identical with the 19sPtsignal we have observed for KPt(DMSO)Cl3,I2 confirms the presence of the complex anion (Pt(DMSO)Cl,)- in solution. We do not detect the presence of Pt(DMSO),C12 6 (195Pt)= -3455)12 in solutions of Pt(thiamin)Cl,. Due to the large trans effect of DMSO and its negative charge, (Pt(DMSO)Cl,)- is very reactive toward the positively charged thiamin molecule. The course of this subsequent reaction is currently under study. Registry No. I, 11 1290-95-0; 11, 11 1290-96-1; 111, 11 1290-97-2; K2PtCI4, 10025-99-7; Pt(DMSO)CI), 31203-96-0; (Hthiamin)C12, 6703-8; (thiamin)NO,, 532-43-4; IP5Pt, 14191-88-9. Supplementary Material Available: Listings of hydrogen atom parameters for Pt(thiamin)C1,.H20 (Table XIII) and anisotropic temperature factors (Tables XIV-XVI) and best weighted least-squares planes (Tables XVII-XIX) for (Hthiamin)PtCI,, (Hthiamin),(PtClp)C12.2H20, and Pt(thiamin)CI,.H,O and two oRTEP diagrams of stacking and interbase interactions in Pt(thiamin)Cl,.H,O (Figures 7 and 8) (9 pages); listings of observed and calculated structure factor amplitudes for all three compounds (48 pages). Ordering information is given on any current masthead page.
(31) Freeman, W.; Pregosini, P. S.;Sze, S. N.; Venanzi, L. M. J . Magn. Reson. 1976, 22, 473-478. (32) Kidd, R. G.; Goodfellow, R. J. In N M R and the Periodic Table; Harris, R. K., Mann, B. E., Eds.; Academic: New York, 1978; p 249. (33) Kidd, R. G.;Goodfellow, R. J. In N M R and the Periodic Table; Harris, R. K.,Mann, B. E., Eds.; Academic: New York, 1978; p 252. (34) Adeyemo, A.; Oderinde, R.; Turner, A,; Shamin, A. Bull. SOC.Chim. Belg. 1987, 96, 15-22.
Contribution from the Department of Chemistry, University of Queensland, Brisbane, Australia 4067
S,O- versus S,N-Chelation in the Reactions of the cis -Diamminediaquaplatinum(11) Cation with Methionine and S-Methylcysteine' Trevor G. Appleton, Jeffrey W. Connor, and John R. Hall* Received May 19, 1987 The reactions of cis-Pt(NH3),(H20),2+ with S-methyl-L-cysteine (mecysH) and L-methionine (metH) have been followed by 'H, I3C, 15N, and 195PtNMR (the last two with ammine ligands substituted with I5N). With a small excess of platinum, and with pH maintained near 5 , the chelate products Pt(NH,),(mecys-S,N)+ and Pt(NH3)2(met-S,N)* are formed. In each case, the different configurations about sulfur give two slowly interconverting diastereomers. In strongly acidic solution (pH 10.5), the initial product in the reaction with mecysH is Pt(NH,),(mecy~H-S,0)~+(two diastereomers), which slowly converts to the S,N-chelate. A similar reaction sequence occurs with methionine, but ~ i s - P t ( N H ~ ) ~ ( m e t H - Sis) ~also * + formed, in competition with Pt(NH3)2(metH-S,0)2*. All of these complexes slowly lose ammonia on standing.
(1) Presented in part at the Third International Conference on Bioinorganic Chemistry, Noordwijkerhout, The Netherlands, July 1987: Appleton, T. G.; Connor, J. W.; Hall, J. R. Recl. Trau. Chim. Pays-Bas 1987,106, 382. (2) Freeman, H. C.; Golomb, M. L. J . Chem. Soc., Chem. Commun. 1970, 1523. (3) Theodorou, V.; Photaki, I.; Hadjiliadis, N.; Gellert, R. W.; Bau, R. Inorg. Chim. Acta 1982, 60, 1.
0020-1669/88/1327-0130$01.50/0
(4) Battaglia, L. P.; Corradi, A. B.; Palmieri, C . G.; Nardelli, M.; Tani, M.
E. V. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1973,829, 762. ( 5 ) Jezowska-Trzebiatowska, B.; Allain, A.; Kozlowski, H. Bull. Acad. Pol. Sci., Ser. Sci. Chim. 1977, 25, 971. ( 6 ) Jezowska-Trzebiatowska, B.; Allain, A,; Kozlowski, H. Inorg. Nucl. Chem. Lett. 1979, 15, 279.
0 1988 American Chemical Society
Inorganic Chemistry, Vol. 27, No. 1 , 1988 131
Reactions of c ~ s - P ~ ( N H ~ ) ~ ( Hwith ~ OAmino ) ~ ~ + Acids Table I. '9JPt and "N N M R Data'
I5N (ammine) comDd Pt(NH3)2(mecys-S,N)tf
struct
2
PH 5
isomer a
6Rb
e
b Pt(NH3)2(mecysH-S,N)2tf
3
0.5
a
-3218 (b)
b Pt(NH,),(met-S,N)'
4
7
major (b?)
e
minor (a?) Pt(NH3)2(metH-S,N)2tg
5
0.5
Pt(NH3)2(mecysH-S,0)2+
6
0.5
Pt(NH3)2(metH-S,0)2t
Pt(NH3)2(metH-S)2t
7
8
0.5
0.5
-3136 (b) h
-2686 (dd)
major
-2652 (dd)
minor
-2618 (dd)
major minor
-3639 (t) -3685 (t)
6NC
-47.6 -67.4 -47.2 -61.4 -41.6 -67.7 -47.4 -61.5 -42.2 -61.9 -42.2 -62.1 -42.4 -62.3 -37.6 -39.7 -82.5 -84.5 -40.1 -82.5 -43.3 -82.5 -42.4
J(Pt-N)d
donor atom trans
255.6 279.8 255.4 219.8 257.3 286.2 257.3 286.2 252.9 279.8 259.2 279.8 252.9 285.2
S N S N S N S N
280.2
S
N S
N S N S
0 270.0 368.1 264.0 348.6 264
S 0 S 0 S
"All ammine ligands ISN substituted and cis. Chemical shifts are shown to lower shielding. *Relative to Na,PtCI, ( f 5 ppm). Abbreviations: b, broad; dd, doublet of doublets; t, 1:2:1 triplet. 'Relative to IsNH4+ (3~0.05ppm). dMeasured from I5N spectrum, f l Hz. CNotmeasured. 'See text for assignment of peaks to particular isomers. gPeaks due to different diastereomers not resolved. hAssignment of peaks to particular isomers not attempted.
in solution, with two diastereomers interconverting slowly enough (NH3)(acmet-S)Clz,and a large peak from lsNH4+. Kostic et to allow separate sets of signals to be observed for them both.7 al. have measured the variable-temperature lgSPtN M R spectra of K[PtCl,(acmet-S)] and the N-acetyl-S-methylcysteineanalogue Diammine complexes [Pt(NH,),(L)]Cl have been obtained by reaction of Pt(LH)Cl, with excess ammonia.s-" Spectroscopic and shown that two platinum signals observed at low temperatures and chemical data have usually been interpreted in terms of coalesce at higher temperatures as the rate of inversion at sulfur S,N-chelation, although Shanjin et al." have suggested S,Oincreases. chelation on the basis of a value for vasrm(C02)higher than exExperimental Section pected for deprotonated carboxylate. It has been notedss9 that Starting Materials. ('5NH4)2S04(99% lSN,Stohler) was supplied by ammonia coordinated trans to sulfur in Pt(NH&(met)+ is laNovachem (Melbourne). L-Methionine (Hopkins and Williams) and bilized and that reaction of ~ i s - P t ( N H ~ ) ~with c l , methionine gives S-methyl-L-cysteine (Sigma) were used as supplied. cis-Pt(NH3)*a mixture of products, with liberation of some ammonia.', (ON02)2(with either I4N or ISNin the ammine ligands) was prepared We have recently used multinuclear N M R to study the reacas previously d e ~ c r i b e d . ' ~ ~Samples ~" of C ~ ~ - P ~ ( N D ~ ) ~ were (ONO~)~ prepared by allowing a solution of c i ~ - P t ( N H ~ ) ~ ( o in N 0D~2 )0~to stand tions in solution between C ~ S - P ~ ( N H ~ ) ~ ( H , O ~ + amino (1)) ,and for several days, followed by evaporation over silica gel in a vacuum acids +NH3(CH2),,CO2-(n = 1-3).13J4 Coordination to platinum desiccator. is initially through carboxylate oxygen, with the rate of subsequent Instrumentation. The 10.1-MHz 15N,21.4-MHz 19sPt,25.05-MHz formation of a N,O-chelate ring very dependent on the chain 13C, and 100-MHz 'H N M R spectra were run as previously delength, n. More complex amino poly(~arboxy1ate)'~ and amino s ~ r i b e d " J ~on> a~ JEOL FX-100 instrument with a 10-mm tunable probe poly(phosphonate) l 5 ligands were also shown by these methods (a 5-mm tube was used for 'H spectra). An internal lock on deuterium to coordinate initially through a single oxygen atom, with subof the solvent D 2 0 was used for I3C and 'H spectra. Other spectra were sequent formation of chelate rings. run with a 'Li external lock. The 400-MHz 'H and 100.4-MHz " C In this paper, we describe the use of multinuclear N M R in spectra were run with an internal deuterium lock on a JEOL GX-400 instrument. The 'H spectra were run with either a 5-mm 'H or a 5-mm characterizing the products of reactions in solution between 1 and 13C/'H probe. A total of 32K data points were used, with spectrum the amino acids L-methionine and S-methyl-L-cysteine. Ismail and Sadler have reported briefly16 that C ~ S - P ~ ( ' ~ N Hwith ~ ) , C ~ ~ width 4 KHz, 16 scans, 45O tilt of magnetization vector, and 3-s delay between pulses. The "C spectra were run with a 10-mm tunable probe. N-acetylmethionine (acmetH) (1:2) at pH 2.2 after 3.5 h at 298 A total of 64K data points were used, with spectrum width 21 kHz, K gave 15N peaks due to ~is-Pt(NH,)~(acmetH-S)Cl+, cis-Pt1000-3000 scans, 45O tilt, and 3-s delay. Kozlowski, H.; Siatecki, Z.; Jezowska-Trzebiatowska, B.; Allain, A. Inorg. Chim. Acta 1980, 46, L25. Volshtein, L. M.; Mogilevkina, M. F. Zh. Neorg. Khim. 1963,8, 304. Volshtein, L. M.; Mogilevkina, M. F. Zh. Neorg. Khim. 1965, 10, 293. Erickson, L. E.; McDonald, J. W.; Howie, J. K.; Clow, R. P. J . A m . Chem. SOC.1968, 90, 6371. Shanjin, X.;Peiyan, D.; Li, Y . ; Kui, W. Fenzi Kexue Yu Huaxue Yanjiu 1984, 4, 537; Chem. Abstr. 1985, 102, 88998q. Volshtein, L. M.; Krylova, L. F.; Mogilevkina, M. F. Zh. Neorg. Khim. 1966, 1 I , 333. Appleton, T. G.; Hall, J. R.; Ralph, S. F. Inorg. Chem. 1985, 24, 673. Appleton, T. G.; Hall, J. R.; Ralph, S. F. Aust. J. Chem. 1986,39, 1347. Appleton, T. G.; Hall, J. R.; McMahon, I. J. Inorg. Chem. 1986, 25, 726. Ismail, I. M.; Sadler, P. J. In Platinum, Gold, and Other Metal ChemofherapeuticAgents; Lippard, S . J.; Ed.; American Chemical Society: Washington, DC, 1983; p 171.
Unless otherwise noted, spectra of all nuclei other than IH were 'Hdecoupled. Chemical shifts are positive to lower shielding. ISN chemical shifts (fO.l ppm) are relative to IsNH4+in a coaxial capillary containing 5 M 'SNH41SN03 in 2 M H N 0 3 . 195Pt-15Ncoupling constants were measured, whenever possible, from the I5N spectra, which, because of narrower line widths, gave more accurate values ( f l Hz) than '95Pt spectra. IssPt shifts ( f 5 ppm) were measured relative to a separate sample of Na2PtC1, in aqueous solution (0.5 g/mL). 13Cshifts (fO.O1 (17) Gummin, D. D.; Ratilla, E. M. A,; Kostic, N. M. Inorg. Chem. 1986, 25, 2429. (18) Galbraith, J. A,; Menzel, K. A,; Ratilla, E. M. A,; Kostic, N. M. Inorg. Chem. 1987, 26, 2073. (19) Boreham, C. J.; Broomhead, J. A.; Fairlie, D. P. Aust. J . Chem. 1981, 34, 659. (20) Appleton, T. G.; Berry, R. D.; Davis, C. A,; Hall, J. R.; Kimlin, H. A. Inorg. Chem. 1984, 23, 3514.
132 Inorganic Chemistry, Vol. 27, No. 1, 1988
Appleton et al.
Table 11. 'H N M R Datad comud Pt(ND,),(mecys-S,N)+
struct 2
uH 5.5
Pt(ND3)2(mecysD-S,N)2+
3
0.5
Pt(ND,),(met-S,N)+
4
5
Pt(ND,)2(metD-S.N)2*
5
0.5
Pt(ND3)2(mecysD-S,0)2+
6
0.5
Pt(ND3),(metD-S.0)2+
7
0.5
Pt(ND3)2(metD-S)22+
8
0.5
isomer major (a) minor (b) major (a) minor (b) major (b?) minor (a?) major (b?) minor (a?)
f
f
major minor
S-CH3 'J(Pt-H) 2.63 50.3 2.57 51.2 2.66 49.8 2.63 50.8 2.53 48.9 2.52 49.8 2.54 d 2.53 d 2.73e 45.8 2.57' 46.0 2.41 d 2.45 d 2.64 44.5 6c~)
CHxb
CH,'
6~~
JAX
JBX
3.83 3.59 4.15 3.91 3.50 3.65 3.75 3.91 4.66 4.62 5.33 5.58
11.3 6.0 11.9 8.3 (10.1) (5.1) (10.6) (5.6) 12.9 12.0 (10.7) (9.5)
4.1 5.6 4.8 5.2 (2.5) (5.1) (2.3) (4.4) 4.9 2.4 (5.2) (6.4)
ha
&is
JAB
3.06 3.12 3.11 3.13
3.04 3.23 3.22 3.41
13.9 13.7 14.2 13.3
2.97 3.32
3.61 3.20
13.0 14.5
In D,O; shifts to lower shielding from TSS. J values are in Hz. All values were measured from 400-MHz spectra, except for Pt-S-CH, coupling constants, which were measured from 100-MHz spectra. bFor S-methylcysteine complexes, for which JAx and JBxwere determined. Spectra of methionine complexes were not fully analyzed, and the values given in parentheses are the "apparent values" from splitting of the Hx signal. For S-methylcysteine complexes only; the methylene region is complex for methionine compounds. dOnly 400-MHz spectra were run. Pt-S-CH, coupling constants were not measured. eS-methyl peaks cannot be associated with particular ABX peaks. 'Not possible to assign peaks to particular isomers,
Table 111. I3C N M R Data' comud mecysD Pt(ND3)2(mecys-S,N)+
struct UD
isomer 15.12 (a) 21.28 (b) 22.45 (a) 21.27 (b) 22.91 24.63 21.33 15.14 major (b?) 20.11 minor (a?) 20.47
Pt(ND3)2(mecysD-S,U)2+c
6
5.3 5.7 major minor 0.5 major minor 0.5 e
metD Pt(ND3)2(met-S,N)+
4
6 6
2
P t ( N D , ) 2 ( m e c y ~ D - S , ~ ~ 2 + 3c
6c
20.5 17.6
65 65
54.32 62.70 63.23 61.12 61.95 52.48 50.96 55.18 58.15 56.09
CH J(Pt-C) 13.9 11.8
17.6 20.5
S-CH2 6c J(Pt-C) 35.53 42.25 67 42.40
