- Email: [email protected]
Absolute structure of a new paramagnetic platinum(II)-creatinine complex with a columnar structure
fo!yhedron Vol. 1 I, No. 3, pp. 365-370, Printed in Great Britain
1992
0277-5387/92 $5.00+.00 Q 1992 Pergamon Press
plc
ABSOLUTE STRUCTURE OF A NEW PARAMAGNETIC PLATINUM(H)-CREATININE COMPLEX WITH A COLUMNAR STRUCTURE G. GENCHEVA,
and G. GOCHEV
M. MITEWA, P. R. BONTCHEV*
Department of Chemistry, University of Sofia, 1126 Sofia, Bulgaria
J. MACICEK
Institute of Applied Mineralogy, Bulgarian Academy of Sciences, Rakovski 92, 1000 Sofia, Bulgaria
E. ZHECHEVA
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria and
N. D. YORDANOV Institute of Kinetics and Catalysis, Bulgarian Academy of Sciences, 1040 Sofia, Bulgaria (Received 20 March 1991; accepted 21 August 1991) Abstract-A
new platinum complex with creatinine [C3H2N2(0)(CH3)NH2] exhibiting paramagnetic properties was synthesized and fully characterized by crystallographic, spectral and magnetic measurements. The compound [AsPh,]+[Pt(creatinine)Cl,]crystallizes to give a columnar honeycomb motif of tetraphenylarsonium cations with the channels occupied by creatinine anions. The shortest Pt-Pt distance is 7.622( 1). A remarkable feature of the structure is the formation of short Pt . . . H intermolecular bonds of 2.73(2) A. The temperature dependence of both peffand EPR parameters of the complex has been studied.
Recently particular interest has been shown towards complexation of Pt” with amide-group ligands, as their ability to form “Platinum Blue” complexes is well documented. I-3 Studying the platinum(I1) reaction with creatinine (a cyclic amide, I) we have proved formation of a variety of platinum complex species, depending on the reaction conditions.“’ In the present paper we report the formation and structure of a new platinum(H) complex with creatinine.
H&
‘\
N
i_ HNLL
N
0
::xa 2
N ‘N
o
I H
EXPERIMENTAL Synthesis
Equimolar (0.05 M) amounts of K,PtC14 (Fluka) * Author to whom correspondence should be addressed. and creatinine (R. de Ha&n) (0.2076 and 0.0566 g, 365
366
G. GENCHEVA
respectively) were dissolved in water and after staying for about 24 h at ambient temperature tetraphenylarsonium (AsPh,)+ solution was added (two-fold excess) resulting in precipitation of oligomerit platinum species.g The latter were filtered off and after several hours green needles of [AsPh,]+ [Pt(creat)ClJ (treat = creatinine) were obtained in the filtrate (pH N 3). They were filtered off, washed repeatedly with water and dried over P205 for several hours.
Crystal data and structure solution A green crystal with approximate dimensions 0.02 x 0.02 x 1.0 mm was mounted on top of a glass capillary and analysed on a computer controlled
et al.
Enraf-Nonius CAD-4 diffractometer. The structure was solved by the heavy-atom method with starting positions of Pt and As atoms elucidated from the Patterson map. The full-matrix least-squares procedure on Fs in combination with the difference Fourier method was used for a completion of the structure. The amino-hydrogen positions of the creatinine ligand were localized and refined with fixed Bs. The other hydrogen positions were calculated and included in refinements as riding atoms. The absolute configuration was established by least-squares refinement of the two enantiomers R = 0.043/0.059, R, = 0.047/0.072, S = 1.117/l .717. All calculations were carried out with an SDP/PDP V 3.0 crystallographic package. Comprehensive crystallographic information is given in Table 1.
Table 1. Crystal data and experimental details Mr
Crystal system Space group a (A) b (A) c (8) B (“) v (A’) Z D, (g cm- “) fi (cm- ‘)
F(OOO) Temperature (K) Monochromator Radiation, I Scan type Scan speed (” min- ‘) Scan width (“) Cell constants from (“) Max sin (0)/n hkl limits Standard reflections Max. intensity variation Reflections measured Transmission factor range Reflections unique &(lFl) Refinement Minimization function Weighting scheme Number of reflections Number of variables
R R s Max. (A/a) Max. (Ap)
197.92 Monoclinic P2 12.997( 1) 7.622( 1) 15.407( 1) 101.02(l) 1434(4) 2 1.848 63.936 766 291 Graphite crystal, incident beam MO-K,, 0.71073 .h @/2e 1 to 7 0.90f0.600 tan (0)
22 reflections, 16.0 < 0 < 17.0 0.745 o/19, - 1l/11, -22/21 3, per 4.0 h f 1% 10343 0.548-1.402 9964 0.027 Full-matrix least-squares M = x w(lF,I -IF&
w = 4F,2/[a2(FX)]*
5419, I > 30(Z) 117 0.043 0.047 1.117 0.066 2.265, -2.117 (e k3)
A new paramagnetic platinum(II)-creatinine
0
OB
\ C
complex
367
b
Fig. 1. The [AsPh,]+ columns projected on the ac-plane exhibit a flattened honeycomb motif. The six-membered channels accommodate the [Pt(creat)Cl,]- anions.
Spectroscopic and magnetochemical measurements The electronic reflectance and IR spectra were recorded on “Perkin-Elmer 330” (spectral range 20&l 500 nm) and “Perkin-Elmer 983” (CsJ-disks, spectral range 400&200 cm- ‘) spectrometers, respectively. The EPR spectra were recorded on an X-band spectrometer Bruker B-ER 420 in the temperature range 100-330 K. The ESCA measurements were performed on spectrometer VIEE-15 (energy calibration according to 1s C line -285.0 eV). The magnetic susceptibility measurements were carried out in the temperature range 15&360 K in an argon atmosphere according to Faraday’s method. RESULTS
Crystal structure of [AsPh,]+[Pt(creat)Cl,]The bulky tetraphenylarsonium cations are arranged in columns parallel to the b-axis (Fig. 1). ‘O*’’ The arsenic atoms are separated in columns by 7.622(2) A and the shortest distances between arsenic atoms from neighbouring columns are 2 x9.275(1) (1 -x, y- l/2, -z; 1 -x, 1/2+y, -z)
and2x9.754(2)(1-x,y-l/2, l-z; l-x, 1/2+y, 1 -z). The channels formed between the columns are filled with complex anions. The mutual dispositions of the anions and the hydrogen bonding scheme may be traced from Fig. 2. The conformation and atom numbering of the anion is depicted in Fig. 3. The selected interatomic distances and angles are given in Table 2. The Pt atom has a square-planar (within 0.021 A) coordination of three chlorine atoms and one endo-nitrogen atom of the creatinine ligand. The non-hydrogen atoms of the creatinine moiety lie in a plane as well (maximum deviation of 0.037 8, is for N(3)). These two planes form a dihedral angle of 95.3(2)“. Such tilting of the creatinine ligand is accompanied by the approach of one of the hydrogen atoms of the amino-group to Pt [Pt ... H(62) 2.7(2) A, N(6)-H(62) * * . Pt 104(8)“, N(6)-H(62) 1.2(2) A]. The second amino-H atom takes part in an intermolecular hydrogen bonding to Cl(2) atom [N(6)-H(61) 1.2(2) A, H(61)*..C1(2) 2.3(2) A, N(6)-H(61)*..C1(2) 144(l)” (x, y-l, z)]. The other two chlorine atoms and the carbonyl oxygen atom are structurally inactive. The shortest nonbonding 0. . . H distances are: O(8)... H(71) (x, l+y, z) 2.6(l) 8, and 0(8)***H(41) (-x, 1/2+y, -z) 2.9(l) A.
368
G. GENCHEVA
et al.
Spectroscopic and magnetochemical data The IR data obtained both for the free ligand and the complex are summarized in Table 3. In the electronic reflectance spectrum of the complex two bands with A,,,,, 320 and 860 nm are present (the latter being rather broad). ESCA data : Pt 4f7,2 73.1 f0.5 eV; Cl 2p 198.6k0.5. The green crystals are paramagnetic showing a complex EPR signal with an orientation dependent g-value and shape (Fig. 4). The temperature dependence of the effective magnetic moment in the range 150-300 K is shown in Fig. 5.
DISCUSSION
HI711
Hf73) H(72)
Hf61)
Fig. 2. A chain sequence of the [Pt(creat)ClJ anions projected on the k-plane. Dashed lines show short contacts of the hydrogen atoms.
The crystallographic and ESCA data indicate an oxidation state of + 2 for the platinum : the Pt-N and interatomic distances in the coordinated creatinine molecule are the same as in the other Pt”creatinine complexes. 5*6,’* The binding energy value of Pt 4fTj2 (73.1 eV) also corresponds to Pt” and this of Cl 2p (198.6 eV) to Cl coordinated in the inner coordination sphere. ’ 3 The IR spectrum of the complex (Table 3) is
Table 2. Selected interatomic distances and angles Pt-Cl( 1) Pt-Cl(2) Pt-Cl(3) Pt-N( 1) As-X( 1a) As-C( 1b) As-X( lc) As-C( 1d) Cl( l)-Pt-C1(2) Cl( l)--Pt-C1(3) Cl( l)-Pt-N( 1) C1(2)--Pt-Cl(3) U(2)-Pt-N( 1) C1(3)-Pt-N( 1) C(la)--As-C(lb) C( 1a)-As--X( 1c) C(la)-As-C(ld) C(lb)--As-C(lc) C(lb)---As-C(ld) C(lc)-As-C(ld)
2.314(2) 2.323(2) 2.316(3) 2.008(8) 1.89(l) 1.914(9) 1.91(l) 1.89(l) 92.0(2) 176.6(l) 88.1(3) 91.5(2) 178.5(2) 88.4(2) 110.1(5) 106.1(6) 112.1(5) 111.3(4) 104.7(4) 112.7(4)
N(l)--C(2) N(l)-C(5) C(2)-N(3) C(2)-N(6) N(3)_C(4) N(3)_C(7) C(4)--C(5) C(5HY8) C(2)-N(l)-C(5) N(l)--C(2)---N(3) N(1 tC(2tN(6) N(3)--C(2)_N(6) C(2)---N(3)--c(4) C(2)_N(3>--c(7) C(4)---N(3)--C(7) N(3)-C(4)-C(5) N(1 )-C(5)-C(4) N(ltc(5>-0(8) C(4)-C(5)_-0(8)
1.36(l) 1.34(l) 1.34(l) 1.31(l) 1.46(l) 1.43(l) 1.52(2) 1.22(l) 109.0(8) 113.0(8) 122.3(9) 124.7(9) 107.9(9) 128(l) 123( 1) 102.0(8) 108.0(9) 128(l) 125(l)
Numbers in parentheses are estimated standard deviations in the least significant digits.
A new parama~etic
platinum(II)-creatinine
369
complex 8.30 H
H(
7) H 171)
Fig. 3. The conformation and atom numbering scheme in the [Pt(creat)Cl,J- anion. The thermal ellipsoids at 50% probability level are used for non-H atoms. The short Pt-H distance is marked by a dashed line.
consistent with the crystallographic data : it is very similar to the spectra of the other Pt”-creatinine complexes,s*6 as the same type of creatinine coordinations is realized. The participation of both H-atoms from the amino-group in H-bonding: intramolecular Pt. - *H(62) and intermolecular H&l) f * - Cl(2) explains the presence of two doublets
in the NH2 symmetric vibrations in the IR spectrum (Table 3). The weak band at 1695 cm-’ may be ascribed to the Pt * . . H vibration1~16 (interatomic distance is 2.7( 1) A). A similar H. - - M (M = platinum group metals) interaction has been observed, the interatomic distances being 2.6-2.9 A.” The chlorine atoms Cl(l) and Cl(3) do not participate in any significant inte~olecul~r interaction. The only weak interaction of the 0 from the carbonyl group with H(41) and H(72) from two different creatinine molecules results in the appearance of two v(C==O) bands observed at high frequencies (Table 3). Taking into account the formal oxidation state of + 2 of the platinum on one hand, and the magnetic
Fig. 4. Orientation dependence of the EPR signal. The sample was rotated in magnetic field and registered at every 90”.
properties and intense green colour on the other it might be assumed that a significant charge transfer takes place along the Pt-Pt chains. As it is seen from crystallographic data (Fig. 1) the structure is built from a honeycomb motif of [AsPh,]+ cations with channels filled with [Pt(creat)Cl~]- anions (shortest Pt-Pt distance is 7.622(l)) and charge-
I 160
I
250
200
I
I
300
360
T(K)
Fig. 5. Temperature dependence of ellective magnetic moment (~1,~).Temperature range 1SO-360 K.
Table 3. Selected IR data for the free ligand and the complex Compound Creatinine [Pt(creat)Cl&[AsPhJ+
v&JH,) 3254br 3412s 3305m
v,(NH 2)
&NH,)
3040br 3258m 3207m
1660s 1657~s
v(M) 1685 1723m 1735m
v(Pt-N) 398m
v(Pt-Cl) 330w sh3lOw
v(Pt 1. . H) 1695
G. GENCHEVA et al.
370
transfer is realized most probably due to the interaction between d-orbitals of Pt and the closely approaching amino H-atom.
7. 8.
authors would like to thank Prof. V. I. Nefedov from the Institute of General and Inorganic Chemistry of the U.S.S.R. Academy of Sciences for ESCA measurements. Acknowledgement-The
REFERENCES
1. J. D. Woollins and P. F. Kelly, Coord. Chem. Rev. 1985,65, 115. 2. B. Lippert, Progr. Znorg. Chem. 1989,37, 1. 3. P. A. Chalouer, Coord. Chem. Rev. 1990,101, 1. 4. P. R. Bontchev, M. Mitewa, G. Gencheva, J. Mac&k, 0. Angelova and V. I. Nefedov, Proc. 11th Conf. Coord. Chem., p. 37. Smolenice, C.S.S.R. (1987). 5. M. Mitewa, G. Gencheva, P. R. Bontchev, 0. Angelova and J. Macicek, Polyhedron 1988, 7, 1237. 6. J. Macicek, 0. Angelova, G. Gencheva, M. Mitewa
9.
10. 11. 12. 13. 14. 15.
and P. R. Bontchev, J. Cryst. Spectr. Res. 1988, 14, 629. P. R. Bontchev, M. Mitewa and G. Gencheva, Pure Appl. Chem. 1989,61,897. M. Mitewa, G. Gencheva and P. R. Bontchev, Proc. 12th Conf. Coord. Chem., p. 253. Smolenice, C.S.S.R. (1989). G. Gochev, N. Yordanov, G. Gencheva, M. Mitewa and P. R. Bontchev, in Electron Magnetic Resonance of Disordered Systems (Edited by N. Yordanov), p. 377. World Scientific Publishers, Singapore (1989). V. U. Mtiler, Acta Cryst. 1980, B36, 1075. P. G. Jones and C. Thiine, Acta Cryst. 1987, B43, 1915. P. T. Beurkens, A. Perales, F. J. Martin-Gil and J. Martin-Gil, Monatsch. Chem. 1988,119, 1189. V. I. Nefedov, Rentgenoelectronnaja Spectroscopia Khimicheskich Soedinenii. Khimia, Moscow (1984). G. G. Hlatky and R. H. Crabtree, Coord. Chem. Rev. 1985,65, 1. F. A. Cotton, T. LaCour and A. G. Stanislowski, J.
Am. Chem. Sot. 1974,%, 754. 16. G. Gliemann and H. Yersin, Struct. Bond. 1985, 62, 87.
1992
0277-5387/92 $5.00+.00 Q 1992 Pergamon Press
plc
ABSOLUTE STRUCTURE OF A NEW PARAMAGNETIC PLATINUM(H)-CREATININE COMPLEX WITH A COLUMNAR STRUCTURE G. GENCHEVA,
and G. GOCHEV
M. MITEWA, P. R. BONTCHEV*
Department of Chemistry, University of Sofia, 1126 Sofia, Bulgaria
J. MACICEK
Institute of Applied Mineralogy, Bulgarian Academy of Sciences, Rakovski 92, 1000 Sofia, Bulgaria
E. ZHECHEVA
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria and
N. D. YORDANOV Institute of Kinetics and Catalysis, Bulgarian Academy of Sciences, 1040 Sofia, Bulgaria (Received 20 March 1991; accepted 21 August 1991) Abstract-A
new platinum complex with creatinine [C3H2N2(0)(CH3)NH2] exhibiting paramagnetic properties was synthesized and fully characterized by crystallographic, spectral and magnetic measurements. The compound [AsPh,]+[Pt(creatinine)Cl,]crystallizes to give a columnar honeycomb motif of tetraphenylarsonium cations with the channels occupied by creatinine anions. The shortest Pt-Pt distance is 7.622( 1). A remarkable feature of the structure is the formation of short Pt . . . H intermolecular bonds of 2.73(2) A. The temperature dependence of both peffand EPR parameters of the complex has been studied.
Recently particular interest has been shown towards complexation of Pt” with amide-group ligands, as their ability to form “Platinum Blue” complexes is well documented. I-3 Studying the platinum(I1) reaction with creatinine (a cyclic amide, I) we have proved formation of a variety of platinum complex species, depending on the reaction conditions.“’ In the present paper we report the formation and structure of a new platinum(H) complex with creatinine.
H&
‘\
N
i_ HNLL
N
0
::xa 2
N ‘N
o
I H
EXPERIMENTAL Synthesis
Equimolar (0.05 M) amounts of K,PtC14 (Fluka) * Author to whom correspondence should be addressed. and creatinine (R. de Ha&n) (0.2076 and 0.0566 g, 365
366
G. GENCHEVA
respectively) were dissolved in water and after staying for about 24 h at ambient temperature tetraphenylarsonium (AsPh,)+ solution was added (two-fold excess) resulting in precipitation of oligomerit platinum species.g The latter were filtered off and after several hours green needles of [AsPh,]+ [Pt(creat)ClJ (treat = creatinine) were obtained in the filtrate (pH N 3). They were filtered off, washed repeatedly with water and dried over P205 for several hours.
Crystal data and structure solution A green crystal with approximate dimensions 0.02 x 0.02 x 1.0 mm was mounted on top of a glass capillary and analysed on a computer controlled
et al.
Enraf-Nonius CAD-4 diffractometer. The structure was solved by the heavy-atom method with starting positions of Pt and As atoms elucidated from the Patterson map. The full-matrix least-squares procedure on Fs in combination with the difference Fourier method was used for a completion of the structure. The amino-hydrogen positions of the creatinine ligand were localized and refined with fixed Bs. The other hydrogen positions were calculated and included in refinements as riding atoms. The absolute configuration was established by least-squares refinement of the two enantiomers R = 0.043/0.059, R, = 0.047/0.072, S = 1.117/l .717. All calculations were carried out with an SDP/PDP V 3.0 crystallographic package. Comprehensive crystallographic information is given in Table 1.
Table 1. Crystal data and experimental details Mr
Crystal system Space group a (A) b (A) c (8) B (“) v (A’) Z D, (g cm- “) fi (cm- ‘)
F(OOO) Temperature (K) Monochromator Radiation, I Scan type Scan speed (” min- ‘) Scan width (“) Cell constants from (“) Max sin (0)/n hkl limits Standard reflections Max. intensity variation Reflections measured Transmission factor range Reflections unique &(lFl) Refinement Minimization function Weighting scheme Number of reflections Number of variables
R R s Max. (A/a) Max. (Ap)
197.92 Monoclinic P2 12.997( 1) 7.622( 1) 15.407( 1) 101.02(l) 1434(4) 2 1.848 63.936 766 291 Graphite crystal, incident beam MO-K,, 0.71073 .h @/2e 1 to 7 0.90f0.600 tan (0)
22 reflections, 16.0 < 0 < 17.0 0.745 o/19, - 1l/11, -22/21 3, per 4.0 h f 1% 10343 0.548-1.402 9964 0.027 Full-matrix least-squares M = x w(lF,I -IF&
w = 4F,2/[a2(FX)]*
5419, I > 30(Z) 117 0.043 0.047 1.117 0.066 2.265, -2.117 (e k3)
A new paramagnetic platinum(II)-creatinine
0
OB
\ C
complex
367
b
Fig. 1. The [AsPh,]+ columns projected on the ac-plane exhibit a flattened honeycomb motif. The six-membered channels accommodate the [Pt(creat)Cl,]- anions.
Spectroscopic and magnetochemical measurements The electronic reflectance and IR spectra were recorded on “Perkin-Elmer 330” (spectral range 20&l 500 nm) and “Perkin-Elmer 983” (CsJ-disks, spectral range 400&200 cm- ‘) spectrometers, respectively. The EPR spectra were recorded on an X-band spectrometer Bruker B-ER 420 in the temperature range 100-330 K. The ESCA measurements were performed on spectrometer VIEE-15 (energy calibration according to 1s C line -285.0 eV). The magnetic susceptibility measurements were carried out in the temperature range 15&360 K in an argon atmosphere according to Faraday’s method. RESULTS
Crystal structure of [AsPh,]+[Pt(creat)Cl,]The bulky tetraphenylarsonium cations are arranged in columns parallel to the b-axis (Fig. 1). ‘O*’’ The arsenic atoms are separated in columns by 7.622(2) A and the shortest distances between arsenic atoms from neighbouring columns are 2 x9.275(1) (1 -x, y- l/2, -z; 1 -x, 1/2+y, -z)
and2x9.754(2)(1-x,y-l/2, l-z; l-x, 1/2+y, 1 -z). The channels formed between the columns are filled with complex anions. The mutual dispositions of the anions and the hydrogen bonding scheme may be traced from Fig. 2. The conformation and atom numbering of the anion is depicted in Fig. 3. The selected interatomic distances and angles are given in Table 2. The Pt atom has a square-planar (within 0.021 A) coordination of three chlorine atoms and one endo-nitrogen atom of the creatinine ligand. The non-hydrogen atoms of the creatinine moiety lie in a plane as well (maximum deviation of 0.037 8, is for N(3)). These two planes form a dihedral angle of 95.3(2)“. Such tilting of the creatinine ligand is accompanied by the approach of one of the hydrogen atoms of the amino-group to Pt [Pt ... H(62) 2.7(2) A, N(6)-H(62) * * . Pt 104(8)“, N(6)-H(62) 1.2(2) A]. The second amino-H atom takes part in an intermolecular hydrogen bonding to Cl(2) atom [N(6)-H(61) 1.2(2) A, H(61)*..C1(2) 2.3(2) A, N(6)-H(61)*..C1(2) 144(l)” (x, y-l, z)]. The other two chlorine atoms and the carbonyl oxygen atom are structurally inactive. The shortest nonbonding 0. . . H distances are: O(8)... H(71) (x, l+y, z) 2.6(l) 8, and 0(8)***H(41) (-x, 1/2+y, -z) 2.9(l) A.
368
G. GENCHEVA
et al.
Spectroscopic and magnetochemical data The IR data obtained both for the free ligand and the complex are summarized in Table 3. In the electronic reflectance spectrum of the complex two bands with A,,,,, 320 and 860 nm are present (the latter being rather broad). ESCA data : Pt 4f7,2 73.1 f0.5 eV; Cl 2p 198.6k0.5. The green crystals are paramagnetic showing a complex EPR signal with an orientation dependent g-value and shape (Fig. 4). The temperature dependence of the effective magnetic moment in the range 150-300 K is shown in Fig. 5.
DISCUSSION
HI711
Hf73) H(72)
Hf61)
Fig. 2. A chain sequence of the [Pt(creat)ClJ anions projected on the k-plane. Dashed lines show short contacts of the hydrogen atoms.
The crystallographic and ESCA data indicate an oxidation state of + 2 for the platinum : the Pt-N and interatomic distances in the coordinated creatinine molecule are the same as in the other Pt”creatinine complexes. 5*6,’* The binding energy value of Pt 4fTj2 (73.1 eV) also corresponds to Pt” and this of Cl 2p (198.6 eV) to Cl coordinated in the inner coordination sphere. ’ 3 The IR spectrum of the complex (Table 3) is
Table 2. Selected interatomic distances and angles Pt-Cl( 1) Pt-Cl(2) Pt-Cl(3) Pt-N( 1) As-X( 1a) As-C( 1b) As-X( lc) As-C( 1d) Cl( l)-Pt-C1(2) Cl( l)--Pt-C1(3) Cl( l)-Pt-N( 1) C1(2)--Pt-Cl(3) U(2)-Pt-N( 1) C1(3)-Pt-N( 1) C(la)--As-C(lb) C( 1a)-As--X( 1c) C(la)-As-C(ld) C(lb)--As-C(lc) C(lb)---As-C(ld) C(lc)-As-C(ld)
2.314(2) 2.323(2) 2.316(3) 2.008(8) 1.89(l) 1.914(9) 1.91(l) 1.89(l) 92.0(2) 176.6(l) 88.1(3) 91.5(2) 178.5(2) 88.4(2) 110.1(5) 106.1(6) 112.1(5) 111.3(4) 104.7(4) 112.7(4)
N(l)--C(2) N(l)-C(5) C(2)-N(3) C(2)-N(6) N(3)_C(4) N(3)_C(7) C(4)--C(5) C(5HY8) C(2)-N(l)-C(5) N(l)--C(2)---N(3) N(1 tC(2tN(6) N(3)--C(2)_N(6) C(2)---N(3)--c(4) C(2)_N(3>--c(7) C(4)---N(3)--C(7) N(3)-C(4)-C(5) N(1 )-C(5)-C(4) N(ltc(5>-0(8) C(4)-C(5)_-0(8)
1.36(l) 1.34(l) 1.34(l) 1.31(l) 1.46(l) 1.43(l) 1.52(2) 1.22(l) 109.0(8) 113.0(8) 122.3(9) 124.7(9) 107.9(9) 128(l) 123( 1) 102.0(8) 108.0(9) 128(l) 125(l)
Numbers in parentheses are estimated standard deviations in the least significant digits.
A new parama~etic
platinum(II)-creatinine
369
complex 8.30 H
H(
7) H 171)
Fig. 3. The conformation and atom numbering scheme in the [Pt(creat)Cl,J- anion. The thermal ellipsoids at 50% probability level are used for non-H atoms. The short Pt-H distance is marked by a dashed line.
consistent with the crystallographic data : it is very similar to the spectra of the other Pt”-creatinine complexes,s*6 as the same type of creatinine coordinations is realized. The participation of both H-atoms from the amino-group in H-bonding: intramolecular Pt. - *H(62) and intermolecular H&l) f * - Cl(2) explains the presence of two doublets
in the NH2 symmetric vibrations in the IR spectrum (Table 3). The weak band at 1695 cm-’ may be ascribed to the Pt * . . H vibration1~16 (interatomic distance is 2.7( 1) A). A similar H. - - M (M = platinum group metals) interaction has been observed, the interatomic distances being 2.6-2.9 A.” The chlorine atoms Cl(l) and Cl(3) do not participate in any significant inte~olecul~r interaction. The only weak interaction of the 0 from the carbonyl group with H(41) and H(72) from two different creatinine molecules results in the appearance of two v(C==O) bands observed at high frequencies (Table 3). Taking into account the formal oxidation state of + 2 of the platinum on one hand, and the magnetic
Fig. 4. Orientation dependence of the EPR signal. The sample was rotated in magnetic field and registered at every 90”.
properties and intense green colour on the other it might be assumed that a significant charge transfer takes place along the Pt-Pt chains. As it is seen from crystallographic data (Fig. 1) the structure is built from a honeycomb motif of [AsPh,]+ cations with channels filled with [Pt(creat)Cl~]- anions (shortest Pt-Pt distance is 7.622(l)) and charge-
I 160
I
250
200
I
I
300
360
T(K)
Fig. 5. Temperature dependence of ellective magnetic moment (~1,~).Temperature range 1SO-360 K.
Table 3. Selected IR data for the free ligand and the complex Compound Creatinine [Pt(creat)Cl&[AsPhJ+
v&JH,) 3254br 3412s 3305m
v,(NH 2)
&NH,)
3040br 3258m 3207m
1660s 1657~s
v(M) 1685 1723m 1735m
v(Pt-N) 398m
v(Pt-Cl) 330w sh3lOw
v(Pt 1. . H) 1695
G. GENCHEVA et al.
370
transfer is realized most probably due to the interaction between d-orbitals of Pt and the closely approaching amino H-atom.
7. 8.
authors would like to thank Prof. V. I. Nefedov from the Institute of General and Inorganic Chemistry of the U.S.S.R. Academy of Sciences for ESCA measurements. Acknowledgement-The
REFERENCES
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