Iminoacylation. 3. Formation of platinum(IV)-based metallaligands due to facile one-end addition of vic-dioximes to coordinated organonitriles1-3

Article abstract of DOI:10.1021/ic990552m

The reaction of vic-dioximes with the organonitrile platinum(IV) complexes trans-[PtCl₄(RCN)₂] (R = Me, CH_2- Ph, Ph, vic-dioxime = dimethylglyoxime; R = Me, vic-dioxime = cyclohexa-, cyclohepta-, and cyclooctanedione dioximes) proceeds rapidly under relatively mild conditions and affords products of one-end addition of the dioximes to the nitrile carbon, i.e. [PtCl₄(NH = C(R)ON = {spacer} = NOH)₂] (1-6) (R = Me, CH₂Ph, Ph, spacer = C(Me)C-(Me) for dimethylglyoxime; R = Me, spacer = C{C₄H₈}C, C{C₅H(10)}C, C{C₆H(12)}C for the other dioximes), giving a novel type of metallaligand. All addition compounds were characterized by elemental analyses (C, H, N, Cl, Pt), FAB mass spectrometry, and IR and ¹H, (13)C{¹H}, and (195)Pt NMR spectroscopy. X-ray structure determination of the dimethylformamide bis-solvate [PtCl₄(NH = C(Me)ON = C(Me)C(Me) = NOH)₂]·2DMF (1a) disclosed its overall trans geometry with the dimethylglyoxime part in anti configuration and the amidine one-end (rather than N,N-bidentate) coordination mode of the N-donor ligands. When a mixture of cis- and trans-[PtCl₄(MeCN)₂] in MeCN was treated with dimethylglyoxime, the formation of, correspondingly, cis- and trans-[PtCl₄(NH = C(Me)ON = C(Me)C(Me) = NOH)₂] (1) was observed and cis-to-trans isomerization in DMSO-d₆ solution was monitored by ¹H, 2D [¹H, ¹⁵)N] HMQC, and (195)Pt NMR spectroscopies. Although performed ab initio calculations give evidence that the trans geometry is the favorable one for the iminoacylated species [PtCl_4- (ligand)₂], the platinum(IV) complex [PtCl₄(NH = C(Me)ON = C{C₄H₈}C = NOH)₂] (4) was isolated exclusively in cis configuration with the two metallaligand 'arms' held together by intramolecular hydrogen bonding between the two peripheral OH groups, as it was proved by single-crystal X-ray diffractometry. The classic substitution products, e.g. [PtCl₂(N,N-dioximato)₂] (12-15), are formed in the addition reaction as only byproducts in minor yield; two of them, [PtCl₂(C₇H₁₁N₂O₂)₂] (14) and [PtCl₂(C₈H₁₃N₂O₂)₂] (15), were structurally characterized. Complexes (12-15) were also prepared by reaction of the vic-dioximes with [PtCl₄L(Me₂SO)] (L = Me₂SO, MeCN), but monoximes (Me₂C = NOH, {C₄H₈}C = NOH, {C₅H(10)}C = NOH, PhC(H) = NOH, (OH)C₆H₄C(H) = NOH) react differently adding to [PtCl₄(MeCN)(Me₂SO)] to give the corresponding iminoacylated products [PtCl_4- (NH = C(Me)ON = CRR')(Me₂SO)] (7-11).

Full text of DOI:10.1021/ic990552m

216
Inorg. Chem. 2000, 39, 216-225
Iminoacylation. 3. Formation of Platinum(IV)-Based Metallaligands Due to Facile One-End
Addition of Wic-Dioximes to Coordinated Organonitriles1-3
Vadim Yu. Kukushkin,*,4a Tatyana B. Pakhomova,4b Nadezhda A. Bokach,4b
Gabriele Wagner,4c Maxim L. Kuznetsov,4c Markus Galanski,4d and
Armando J. L. Pombeiro*,4c
Department of Chemistry, St. Petersburg State University, 198904 Stary Petergof, Russian Federation,
Inorganic Chemistry, St. Petersburg State Technological Institute, Zagorodny Pr. 49, 198013 St.
Petersburg, Russian Federation, Complexo I, Instituto Superior Te´cnico, Av. Rovisco Pais,
1049-001 Lisbon, Portugal, and Institute for Inorganic Chemistry, University of Vienna,
Wa¨hringer Strasse 42, A-1090 Vienna, Austria
ReceiVed May 18, 1999
The reaction of Vic-dioximes with the organonitrile platinum(IV) complexes trans-[PtCl4(RCN)2] (R ) Me, CH2-
Ph, Ph, Vic-dioxime ) dimethylglyoxime; R ) Me, Vic-dioxime ) cyclohexa-, cyclohepta-, and cyclooctanedione
dioximes) proceeds rapidly under relatively mild conditions and affords products of one-end addition of the dioximes
to the nitrile carbon, i.e. [PtCl4(NHdC(R)ONd{spacer}dNOH)2] (1-6) (R ) Me, CH2Ph, Ph, spacer ) C(Me)C-
(Me) for dimethylglyoxime; R ) Me, spacer ) C{C4H8}C, C{C5H10}C, C{C6H12}C for the other dioximes),
giving a novel type of metallaligand. All addition compounds were characterized by elemental analyses (C, H, N,
Cl, Pt), FAB mass spectrometry, and IR and 1H, 13C{1H}, and 195Pt NMR spectroscopy. X-ray structure
determination of the dimethylformamide bis-solvate [PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2]‚2DMF (1a)
disclosed its overall trans geometry with the dimethylglyoxime part in anti configuration and the amidine one-
end (rather than N,N-bidentate) coordination mode of the N-donor ligands. When a mixture of cis- and trans-
[PtCl4(MeCN)2] in MeCN was treated with dimethylglyoxime, the formation of, correspondingly, cis- and trans-
[PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2] (1) was observed and cis-to-trans isomerization in DMSO-d6
solution was monitored by 1H, 2D [1H,15N] HMQC, and 195Pt NMR spectroscopies. Although performed ab initio
calculations give evidence that the trans geometry is the favorable one for the iminoacylated species [PtCl4-
(ligand)2], the platinum(IV) complex [PtCl4(NHdC(Me)ONdC{C4H8}CdNOH)2] (4) was isolated exclusively
in cis configuration with the two metallaligand “arms” held together by intramolecular hydrogen bonding between
the two peripheral OH groups, as it was proved by single-crystal X-ray diffractometry. The classic substitution
products, e.g. [PtCl2(N,N-dioximato)2] (12-15), are formed in the addition reaction as only byproducts in minor
yield; two of them, [PtCl2(C7H11N2O2)2] (14) and [PtCl2(C8H13N2O2)2] (15), were structurally characterized.
Complexes (12-15) were also prepared by reaction of the Vic-dioximes with [PtCl4L(Me2SO)] (L ) Me2SO,
MeCN), but monoximes (Me2CdNOH, {C4H8}CdNOH, {C5H10}CdNOH, PhC(H)dNOH, (OH)C6H4C(H)d
NOH) react differently adding to [PtCl4(MeCN)(Me2SO)] to give the corresponding iminoacylated products [PtCl4-
(NHdC(Me)ONdCRR′)(Me2SO)] (7-11).
Introduction
centered on the preparation of precursors for further synthetic
works,7 investigation of self-assembly of (oxime/oximato)PtII
species by hydrogen bonding,8 oxidation of oximes to give
nitrosoalkanes,9,10 studies on the redox duality of oxime species
toward platinum complexes,11 chlorination of coordinated oxime
ligands,12 and additions of coordinated oximes to ketones upon
oxidation of (oxime)PtII compounds.13
The metal-assisted reactions of oximes and reactivity of oxime
ligands is an area of tremendous variety as it has been
demonstrated in reviews published recently by two of us.5,6 Our
own research in the area of (oxime)Pt chemistry has so far
(1) Dedicated to the memory of Professor Dr. Yuri N. Kukushkin, who
passed away on November 30th, 1998.
(2) For part 1, see: Kukushkin, V. Yu.; Pakhomova, T. B.; Kukushkin,
Yu. N.; Herrmann, R.; Wagner, G.; Pombeiro, A. J. L. Inorg. Chem.
1998, 37, 6511.
(3) For part 2, see: Wagner, G.; Pombeiro, A. J. L.; Kukushkin, Yu. N.;
Pakhomova, T. B.; Ryabov, A. D.; Kukushkin, V. Yu. Inorg. Chim.
Acta 1999, 292, 272.
(4) (a) St. Petersburg State University. Fax: +7812-428 6939. E-mail:
kukushkin@VK2100.spb.edu. (b) St. Petersburg State Technological
Institute. (c) Instituto Superior Te´cnico. Fax: +351-21-8464455.
E-mail: pombeiro@alfa.ist.utl.pt. (d) galanski@pap.univie.ac.at.
(5) Kukushkin, V. Yu.; Tudela, D.; Pombeiro, A. J. L. Coord. Chem. ReV.
1996, 156, 333 and references therein.
(7) Kukushkin, V. Yu.; Izotova, Y. A.; Tudela, D. Inorg. Synth., in press.
(8) Kukushkin, V. Yu.; Nishioka, T.; Tudela, D.; Isobe, K.; Kinoshita, I.
Inorg. Chem. 1997, 36, 6157.
(9) Kukushkin, V. Yu.; Tudela, D.; Izotova, Y. A.; Belsky, V. K.; Stash,
A. I. Inorg. Chem. 1996, 35, 4926.
(10) Kukushkin, V. Yu.; Belsky, V. K.; Aleksandrova, E. A.; Konovalov,
V. E.; Kirakosyan, G. A. Inorg. Chem. 1992, 31, 3836.
(11) Guedes da Silva, M. F. C.; Izotova, Yu. A.; Pombeiro, A. J. L.;
Kukushkin, V. Yu. Inorg. Chim. Acta 1998, 277, 83.
(12) Kukushkin, Yu. N.; Krylov, V. K.; Kaplan, S. F.; Calligaris, M.;
Zangrando, E.; Pombeiro, A. J. L.; Kukushkin, V. Yu. Inorg. Chim.
Acta 1999, 285, 116.
(6) Kukushkin, V. Yu.; Pombeiro, A. J. L. Coord. Chem. ReV. 1999, 181,
(13) Kukushkin, V. Yu.; Belsky, V. K.; Tudela, D. Inorg. Chem. 1996,
35, 510.
147.
10.1021/ic990552m CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/05/2000

Formation of Pt(IV)-Based Metallaligands
Inorganic Chemistry, Vol. 39, No. 2, 2000 217
Scheme 1. Iminoacylation of Salicylaldoxime
Recently we reported on the metal-mediated iminoacylation
reaction of ketoximes or aldoximes, HONdCR1R2, upon treat-
ment with the organonitrile platinum(IV) complexes trans-
[PtCl4(RCN)2] (R ) Me, CH2Ph, Ph) that proceeds under
relatively mild conditions to give trans-[PtCl4(NHdC(R)ONd
CR1R2)2] (R1 ) R2 ) Me; R1R2 ) C4H8, R1R2 ) C5H10, R1R2
) (H)Ph, R1R2 ) (H)C6H4(OH)-o) in almost quantitative yield.2
Our interest in further investigation of the platinum(IV)-assisted
iminoacylation is driven by the following main reasons. First,
the reaction opened up a route for preparation of complexes
containing unusual iminoacylated oxime ligands whose chem-
istry is not yet developed. Second, these species were proved
to be exceptionally stable toward hydrolysis and this property
allows us to assume that the complexes might be useful in
coordination chemistry for modeling elusive monodentate imino
ligands14-16 and in organic chemistry as models of highly
unstable intermediates in a nitrilium ion catalyzed Beckmann
rearrangement.17,18
Figure 1. Vic-Dioximes employed for the iminoacylation.
addition of salicylaldoxime to coordinated acetonitrile species
in trans-[PtCl4(MeCN)2], we wondered whether this synthetic
method might represent a general route to the new type
metallaligands. For this study we addressed Vic-dioximes (Figure
1) a representative of which, viz. dimethylglyoxime, is probably
one of the most classical bidentate chelating ligand. Indeed, in
complete contrast to the traditional views on the reactivity of
dimethylglyoxime and other Vic-dioxime species, we have
isolated compounds of their one-end addition to the nitriles
giving Pt(IV)-based metallaligands rather than the ordinary
substitution products, and these results are reported in this article.
Experimental Section
One more result2 has stimulated our current work. It appeared
that salicylaldoxime, although being a well-known chelating
reagent employed in both synthetic and analytical chemistry for
many years, added to trans-[PtCl4(RCN)2] to give a Pt(IV)-
based metallaligand (Scheme 1).
The chemistry of so-called multimetal-centered complexes
or metal complex assemblies is of current intrinsic interest since
it was demonstrated that metallaligands are proved to be useful
in the design of multimetal systems and the control of their
properties (for reviews see refs 19-23; for recent experimental
work see refs 24-36). In view of the apparent success on the
Materials and Instrumentation. Dimethylglyoxime and cyclohex-
anedione dioxime were purchased from Aldrich and Reakhim, respec-
tively. Solvents were obtained from commercial sources and used as
received. C, H, and N elemental analyses were carried out by
Microanalytical Services of the Instituto Superior Te´cnico and St.
Petersburg Technological Institute, while Cl and Pt were analyzed by
the authors. Decomposition points were determined on a Kofler table.
For TLC, Silufol UV 254 SiO2 plates have been used. Positive-ion
FAB mass spectra were obtained on a Trio 2000 instrument by
bombarding 3-nitrobenzyl alcohol (NBA) matrixes of samples with 8
keV (ca. 1.28 × 1015 J) Xe atoms. Mass calibration for data system
acquisition was achieved using CsI. Infrared spectra (4000-400 cm-1
)
were recorded on a Bio-Rad FTS 3000 Mx instrument in KBr pellets.
1H, 13C{1H}, and 195Pt NMR spectra were measured on a Varian UNITY
300 spectrometer at ambient temperature. 195Pt spectra were recorded
(14) Prenzler, P. D.; Hockless, D. C. R.; Heath G. A. Inorg. Chem. 1997,
36, 5845.
(15) Diamond, S. E.; Tom, G. M.; Taube, H. J. Am. Chem. Soc. 1975, 97,
2661.
1
without H decoupling at a frequency of 64.507 MHz and a spectral
(16) Adcock, P. A.; Keene, F. R.; Smythe, R. S.; Snow, M. R. Inorg. Chem.
1984, 23, 2336.
(17) Glocker, M. O.; Shrestha-Davadi, P. B.; Ku¨chler-Krischun, J.; Hof-
mann, J.; Fischer, H.; Jochims, J. J. Chem. Ber. 1993, 136, 1859.
(18) Meerwein, H. Angew. Chem. 1955, 67, 374.
(19) Stumpf, H. O.; Ouahab, L.; Pei, Y.; Grandjean, D.; Kahn, O. Science
1993, 261, 447.
width of 100 kHz, using a 90° pulse (12.2 µs), an acquisition time of
0.64 s, and a delay of 0.05 s. Chemical shifts were measured relative
to aqueous K2[PtCl4] (-1630 ppm), and half-height line widths are
given in parentheses. 2D [1H,15N] HMQC spectra were recorded on a
Bruker Avance DPX 400 instrument in 5 mm tubes at 24 °C using
1
standard pulse programs supplied by Bruker (2D H/15N correlation
(20) Suib, S. L. Chem. ReV. 1993, 93, 803.
via heteronuclear zero and double quantum coherence, gradient selected
version with decoupling (GARP sequence) during aquisition in a phase
sensitive mode using TPPI). The chemical shifts are reported relative
to external 15NH4Cl (0 ppm).
(21) McCleverty, J. A.; Ward, M. D. Acc. Chem. Res. 1998, 31, 842.
(22) Ward, M. D. Chem. Soc. ReV. 1995, 121.
(23) Garnovsky, A. D.; Sadimenko, A. P.; Uraev, A. I.; Vasilchenko, I.
S.; Garnovsky, D. A. Koord. Khim., in press.
Synthetic Work and Characterization. Complexes trans-[PtCl4-
(RCN)2] (R ) Me, CH2Ph, Ph),2 [PtCl4(MeCN)(Me2SO)],37 and
[PtCl4(Me2SO)2]38 were prepared according to the published methods.
A mixture of cis and trans isomers of [PtCl4(MeCN)2] was prepared
(24) Kajiwara, T.; Ito, T. J. Chem. Soc., Dalton Trans. 1998, 3351.
(25) Lloris, J. M.; Mart´ınez-Ma´n˜ez, Pardo, T.; Soto, J.; Padilla-Tosta, M.
J. Chem. Soc., Dalton Trans. 1998, 2635.
(26) Alessio, E.; Macchi, M.; Heath, S. L.; Marzilli, L. G. Inorg. Chem.
1997, 36, 5614.
(27) Isab, A. A.; Marzilli, L. G. Inorg. Chem. 1998, 37, 6558.
(28) Kingston, J. E.; Ashford, L.; Beer, P. D.; Drew M. G. B. J. Chem.
Soc., Dalton Trans. 1999, 251.
(29) Polborn, K.; Severin, K. J. Chem. Soc., Dalton Trans. 1999, 759.
(30) Briel, O.; Su¨nkel, K.; Krossing, I.; No¨th, H.; Schma¨lzlin, E.; Meerholz,
K.; Bra¨uchle, C.; Beck, W. Eur. J. Inorg. Chem. 1999, 483.
(31) Liu, T.-Y.; Chen, Y. J.; Tai, C.-C.; Kwan, K. S. Inorg. Chem. 1999,
38, 674.
(33) Lei, X.; Shang, M.; Fehlner, T. P. J. Am. Chem. Soc. 1999, 121, 1275.
(34) Schneider, J. J.; Czap, N.; Bla¨ser, D.; Boese, R. J. Am. Chem. Soc.
1999, 121, 1409.
(35) Fabre, S.; Findeis, B.; Tro¨sch, D. J. M.; Gade, L. H.; Scowen, I. J.;
McPartlin, M. Chem. Commun. 1999, 577.
(36) Kruger, P. E.; Launay, F.; McKee, V. Chem. Commun. 1999, 639.
(37) Kukushkin, V. Yu.; Zenkevich, I. G.; Belsky, V. K.; Konovalov, V.
E.; Moiseev, A. I.; Sidorov, E. O. Inorg. Chim. Acta 1989, 166, 79.
(38) Kukushkin, V. Yu.; Pankova, E. Yu. Koord. Khim. 1989, 15, 531.
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1998, 37, 6832.

218 Inorganic Chemistry, Vol. 39, No. 2, 2000
Kukushkin et al.
by passage of Cl2 gas through suspension of cis and trans isomers of
[PtCl2(MeCN)2]39,40 in MeCN for 15 min with vigorous stirring.
Reactions of [PtCl4(RCN)2] (R ) Me, CH2Ph, Ph) with dimeth-
ylglyoxime and reactions of [PtCl4(MeCN)2] with the other dioximes
were carried out as we previously reported2 upon treatment of the
platinum(IV) starting materials with the Vic-dioximes in a molar ratio
1:2.5 in MeCN or CHCl3 at 55-60 °C.
Pt, 27.7. Found: C, 27.6; H, 3.6; N, 11.7; Cl, 20.0; Pt, 27.4. FAB+-
MS, m/z: 667, [M - Cl]+; 632, [M - 2Cl]+. Mp: 156 °C (dec). TLC
on SiO2, Rf ) 0.58 (eluent Me2CO:CHCl3 ) 1:6, v/v). IR spectrum
(selected bands), cm-1: 3434 m, br ν(O-H), 3270 and 3224 m-w ν-
1
(N-H), 1661 vs and 1639 sh ν(CdN), 1151 m-w ν(C-O). H NMR
in DMSO-d6, δ: 1.65 (m, 4H), 2.61 (m, 4H) (C4H8), 2.83 (s + d, 4JPtH
4.0 Hz, 3H, dC(Me)O), 8.98 (s + d, 2JPtH 23.3 Hz, 1H, NH), 12.18 (s,
1 H, OH). 13C{1H} NMR spectrum in DMSO-d6, δ: 17.9 (dC(Me)O),
20.3, 21.3, 25.5, and 26.3 (C4H8), 153.9 (CdN), 164.1 (CdN), 173.3
(dC(Me)O). 195Pt NMR spectrum in DMSO-d6, δ: 57 (350 Hz).
[PtCl4(NHdC(Me)ONdC{C5H10}CdNOH)2] (5). The yield is
80%. Anal. Calcd for C18H30N6Cl4O4Pt: C, 29.6; H, 4.1; N, 11.5; Cl,
19.4; Pt, 30.6. Found: C, 30.0; H, 4.0; N, 11.3; Cl, 19.8; Pt, 27.0.
FAB+-MS, m/z: 576, [M - L]+. Mp: 126-130 °C. TLC on SiO2, Rf
) 0.61(eluent Me2CO:CHCl3 ) 1:2, v/v). IR spectrum (selected bands),
cm-1: 3420 m ν(O-H), 3260 m-w ν(N-H), 1652 s ν(CdN), 1140
[PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2] (1). The yield is
84% with needlelike bright yellow crystals from the reaction mixture;
space group C2/m or C2, a ) 13.817 Å, b ) 8.055 Å, c ) 11.226 Å,
and â ) 120.25°. Anal. Calcd for C12H22N6Cl4O4Pt: C, 22.1; H, 3.4;
N, 12.9; Cl, 21.8; Pt, 30.0. Found: C, 22.4; H, 3.4; N, 12.5; Cl, 22.0;
Pt, 30.4. FAB+-MS, m/z: 615, [M - Cl]+. FAB+-MS in glycerol matrix,
m/z: 673, [M + Na]+. This complex does not have a characteristic
melting point. On heating, it decomposes above 200 °C. TLC on SiO2,
Rf ) 0.61 (eluent CHCl3:Me2CO ) 5:1, v/v). IR spectrum (selected
bands), cm-1: 3438 m ν(O-H), 3284 m-w ν(N-H), 1665 and 1622 s
1
m-w ν(C-O). H NMR spectrum of both isomers in an approximate
1
ratio 2:1 in DMSO-d6, δ: 1.60 (m, 6H), 2.71 (m, 2H), 3.01 (m, 2H,
C5H10), 2.71 (s, 3H, dC(Me)O), 8.60 (s + d, 2JPtH 32.3 Hz, NH of the
trans isomer), 9.06 (s + d, 2JPtH 23.4 Hz, NH of the cis isomer), 11.85
(s, OH of the cis isomer), 11.94 (s, OH of the trans isomer). 13C{1H}
NMR spectrum of both isomers in DMSO-d6, δ: 18.4 and 18.5 (Nd
C(Me)O), 23.5, 26.3, 26.7, 28.5, and 28.8 (C5H10), 155.0 (CdN), 167.3
(CdN), 175.2 (dC(Me)O). 195Pt NMR spectrum in DMSO-d6, δ: for
the cis isomer +76 (369 Hz), for the trans isomer -72 (700 Hz).
[PtCl4(NHdC(Me)ONdC{C6H12}CdNOH)2] (6). The yield is
90%. Anal. Calcd for C20H34N6Cl4O4Pt: C, 31.6; H, 4.5; N, 11.1; Cl,
18.7; Pt, 25.7. Found: C, 30.9; H, 3.9; N, 10.8; Cl, 18.4; Pt, 25.9.
FAB+-MS, m/z: 723, [M - Cl]+; 689, [M - 2Cl + H]+. Mp: 180 °C
(dec). TLC on SiO2, Rf ) 0.63 (eluent CHCl3). IR spectrum (selected
bands), cm-1: 3450 ν(O-H), 3285 m-w ν(N-H), 1660 and 1643 m
ν(CdN), 1199 m ν(C-O). H NMR spectrum in acetone-d6, δ: 2.04
4
and 2.30 (two s, 3H each, dC(Me)C(Me)), 2.73 (s + d, JPtH 3.9 Hz,
3H, dC(Me)O), 8.75 (s, br, NH), 11.50 (s, 1H, OH). 13C{1H} NMR
spectrum in acetone-d6, δ: 175.0 (2JPtC 40.0 Hz, dC(Me)O), 164.7
(ONdC), 151.7 (dC), 17.8 (dC(Me)O), 11.7 and 9.3 (Me). 195Pt NMR
spectrum in acetone-d6, δ: -150 (750 Hz).
Dissolution of 1 in dimethylformamide at room temperature and
keeping the solution for 1 d resulted in precipitation of a small amount
of yellow needlelike crystals of the bis(dimethylformamide) solvate
[PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2]‚2Me2NCHO (1a), whose
structure was studied by X-ray single-crystal diffractometry (see below).
Anal. Calcd for C18H36N8Cl4O6Pt: C, 27.1; H, 4.6; N, 14.1. Found:
C, 27.2; H, 4.7; N, 14.3. FAB+-MS in glycerol matrix, m/z: 615, [M
- Cl]+. IR spectrum (selected bands), cm-1: 3440 m ν(O-H), 3293
m-w ν(N-H), 1667 vs, br and 1622 sh ν(CdN) and ν(CdO), 1200 m
1
ν(CdN), 1190 m ν(C-O). H NMR spectrum in DMSO-d6, δ: 1.49
1
(m, 4H), 1.62 (m, 2H), 1.71 (m, 2H), 2.68 (m, 2H) and 2.88 (m, 2H)
(C8H12), 2.73 (s, 3H, CH3), 8.62 (s + d, 2JPtH 35 Hz, 1H, NH), OH was
not detected. 13C{1H} NMR spectrum in DMSO-d6, δ: 17.9 (CH3),
24.6 (CH2), 24.9 (CH2), 25.2 (CH2), 25.5 (CH2), 25.8 (CH2), 27.6 (CH2),
154.0 (CdN), 168.8 (CdN), 174.5 (dC(Me)O). 195Pt NMR spectrum
in DMSO-d6, δ: -78 (700 Hz).
ν(C-O). H NMR spectrum in DMSO-d6, δ: 2.00 and 2.31 (two s,
4
3H each, dC(Me)C(Me)), 2.77 (s + d, JPtH 3.8 Hz, 3H, dC(Me)O),
2.73 and 2.89 (two s, 3H each, Me2NCHO), 8.83 (s + d, 1H, 2JPtH 34.7
Hz, NH), 12.50 (s, 1H, Me2NCHO).
[PtCl4(NHdC(CH2Ph)ONdC(Me)C(Me)dNOH)2] (2). The yield
is 88%. Anal. Calcd for C24H30N6Cl4O4Pt: C, 35.9; H, 3.8; N, 10.5;
Cl, 17.7; Pt, 24.3. Found: C, 35.6; H, 3.8; N, 10.3; Cl, 18.0; Pt, 23.9.
FAB+-MS, m/z: 733, [M - 2Cl]+; 698, [M - 3Cl]+; 662, [M - 4Cl
- H]+. This complex does not have a characteristic melting point. On
heating, it decomposes above 200 °C. TLC on SiO2, Rf ) 0.67 (eluent
CHCl3). IR spectrum (selected bands), cm-1: 3423 m ν(O-H), 3275
m-w ν(N-H), 1623 m-w ν(CdN), 1163 m ν(C-O). 1H NMR spectrum
in acetone-d6, δ: 2.07 and 2.08 (two s, 3H each, dC(Me)C(Me)), 4.74
(s, 2 H, CH2Ph), 7.37 (m, 3H) and 7.56 (m, 2H, CH2Ph), 9.01 (s, br,
2H, OH, NH). 13C{1H} NMR spectrum in acetone-d6, δ: 174.8 (d
C(CH2Ph)O), 165.8 (ONdC), 152.2 (dC), 133.9, 130.8, 129.5 and
128.4 (Ph), 37.7 (CH2), 11.9 (Me), 9.5 (Me). 195Pt NMR spectrum in
acetone-d6, δ: -164 (840 Hz).
[PtCl4(NHdC(Ph)ONdC(Me)C(Me)dNOH)2] (3). The yield is
83%. Anal. Calcd for C22H26N6Cl4O4Pt: C, 34.1; H, 3.4; N, 10.8; Cl,
18.3; Pt, 25.2. Found: C, 33.8; H, 3.7; N, 10.7; Cl, 18.2; Pt, 25.1.
FAB+-MS, m/z: 739, [M - Cl]+. This complex does not have a
characteristic melting point. On heating, it decomposes above 200 °C.
TLC on SiO2, Rf ) 0.58 (eluent CHCl3:Me2CO ) 8:1, v/v). IR spectrum
(selected bands), cm-1: 3435 m ν(O-H), 3265 m-w ν(N-H), 1650
m-w and 1623 m-w ν(CdN), 1180 or 1143 m ν(C-O). 1H NMR
spectrum in acetone-d6, δ: 2.04 and 2.30 (two s, 3H each, dC(Me)C-
(Me)), 7.47 (t, 6.8 Hz, 2H), 7.64 (t, 6.5 Hz, 1H) and 8.07 (d, 7.2 Hz,
2H) (Ph), 9.52 (s, br 1H, NH), OH not detected. 13C{1H} NMR spectrum
in DMSO-d6, δ: 172.2 (dC(Ph)O), 166.3 (ONdC), 153.0 (dC); 132.3,
129.5 and 127.9 (Ph, quarternary carbon was not observed), 9.3 (Me),
9.2 (Me). 195Pt NMR spectrum in DMSO-d6, δ: -78 (700 Hz).
[PtCl4(NHdC(Me)ONdC{C4H8}CdNOH)2] (4). The yield is 82%.
Anal. Calcd for C16H26N6Cl4O4Pt: C, 27.3; H, 3.7; N, 12.0; Cl, 20.2;
Reaction of [PtCl4(MeCN)(Me2SO)] with HONdCMe2, HONd
C(C4H8), HONdC(C5H10), HONdC(H)Ph, and HONdC(H)C6H4-
(OH) proceeds as described above upon treatment of the platinum(IV)
starting materials with the oximes in a molar ratio 1:1.3 in MeCN.
[PtCl4(NHdC(Me)ONdCMe2)(Me2SO)] (7). The yield is 81%.
Anal. Calcd for C7H16N2Cl4O2PtS: C, 15.9; H, 3.1; N, 5.3; Cl, 26.8;
Pt, 36.9. Found: C, 15.6; H, 3.2; N, 5.2; Cl, 26.7; Pt, 36.9. FAB+-MS,
m/z: 495, [M - Cl, +2H]+; 456, [M - 2HCl]+; 421, [M - 2HCl,
-Cl]+. Mp: 122 °C. TLC on SiO2, Rf ) 0.42 and 0.60 (eluent acetone:
CHCl3 1:12). IR spectrum (selected bands), cm-1: 3011 and 2921 m
ν(N-H), 1664 s and 1641 vs ν(CdN), 1169 s and/or 1188 s ν(SdO).
1H NMR spectrum for cis and trans isomers in an approximate ratio
2:1 in CDCl3, δ: for the cis isomer 2.07 and 2.08 (s, 3H each, CMe2),
4
3
2.69 (s + d, JPtH 3.6 Hz, 3H, dC(Me)O), 3.70 (s + d, JPtH 15.0 Hz,
6H, Me2SO), 8.38 (s, br, NH); for the trans isomer 2.08 and 2.09 (s,
3H each, CMe2), 2.68 (s + d, 3JPtH 3.6 Hz, 3H, dC(Me)O), 3.72 (s +
d, 3JPtH 13.6 Hz, 6H, Me2SO), 8.58 (s, br, NH). 13C{1H} NMR spectrum
for both isomers in CDCl3, δ: 18.3 (s + d, 3JPtC 6.7 Hz, NdC(Me)O),
17.5 and 21.9 (CMe2), 40.6 (2JPtC 28.9 Hz, Me2SO of the cis isomer)
and 42.0 (2JPtC 32.7 Hz, Me2SO of the trans isomer), 166.4 (CdNMe2),
174.5 (HNdC). 195Pt NMR spectrum in DMSO-d6, δ: for the cis isomer
1
14
-966 (t, JPt 260 Hz) and for the trans isomer -1082 (400 Hz).
N
[PtCl4(NHdC(Me)ONdC{C4H8})(Me2SO)] (8). The yield is 74%.
Anal. Calcd for C9H18N2Cl4O2PtS: C, 19.5; H, 3.3; N, 5.1; Cl, 25.5;
Pt, 35.1. Found: C, 19.3; H, 3.3; N, 5.4; Cl, 25.2; Pt, 34.9. FAB+-MS,
m/z: 507, [M - 2Cl + Na]+. Mp: 104 °C. TLC on SiO2, Rf ) 0.60
and 0.71 (eluent acetone:CHCl3 ) 1:8, v/v). IR spectrum (selected
bands), cm-1: 3008 w, 2968 w and 2918 w-m ν(N-H), 1639 vs ν-
(CdN), 1180 s ν(SdO). 1H NMR spectrum of both isomers in an
approximate ratio 1:1 in CDCl3, δ: 2.72 and 2.73 (s, 3H each,
(39) Fanizzi, F. P.; Intini, F. P.; Maresca, L.; Natile, G. J. Chem. Soc.,
Dalton Trans. 1990, 199.
(40) Kukushkin, V. Yu.; Tkachuk, V. M.; Vorobiov-Desiatovsky, N. V.
Inorg. Synth. 1998, 32, 144.
3
dC(Me)O), 1.90 (m, 8H) and 2.64 (m, 8H)(C4H8), 3.76 (s + d, JPtH
3
14.4 Hz, 6H, Me2SO), 3.78 (s + d, JPtH 13.3 Hz, 6H, Me2SO), 8.30
(s, br, 1H, NH), 8.58 (s, br, 1H, NH). 13C{1H} NMR spectrum of both

Formation of Pt(IV)-Based Metallaligands
Inorganic Chemistry, Vol. 39, No. 2, 2000 219
isomers in CDCl3, δ: 18.4 (NdC(Me)O), 24.4, 25.0, 30.1, and 31.7
(C4H8), 40.5 (2JPtC 28 Hz) and 41.8 (2JPtC 32 Hz)(Me2SO), 174.8 (HNd
C), and 178.0 (CdN(C4H8)). 195Pt NMR spectrum in DMSO-d6, δ: for
is heated at 50-60 °C for ca. 5 min on stirring until homogenization
is completed. The solutions formed are cooled to 20-25 °C and left to
stand without stirring. In the case of dimethylglyoxime a product
precipitates after 5 h, while in the other cases release of products was
observed after ca. 30 min. The precipitate is collected on a filter shortly
after appearance, washed with three 2-mL portions of diethyl ether,
and dried in air at 20-25 °C. Keeping the precipitates in the suspension
results in contamination of the products with the platinum(II) complexes
[Pt(dioximato)2]. Yields of [PtCl2(dioximato)2] are ca. 50%, based on
Pt.
the cis isomer -970 (t, 1JPt N 240 Hz) and for the trans isomer -1082
14
(400 Hz).
[PtCl4(NHdC(Me)ONdC{C5H10})(Me2SO)] (9). The yield is 76%.
Anal. Calcd for C10H20N2Cl4O2PtS: C, 21.1; H, 3.5; N, 4.9; Cl, 24.9;
Pt, 34.3. Found: C, 21.2; H, 3.7; N, 5.2; Cl, 25.2; Pt, 34.6. FAB+-MS,
m/z: 533, [M - Cl]+; 498, [M - 2Cl]+; 463, [M - 3Cl]+. Mp: 112
°C. TLC on SiO2, Rf ) 0.62 and 0.71 (eluent acetone:CHCl3 ) 1:8,
v/v). IR spectrum (selected bands), cm-1: 3007 w, 2921 m, and 2858
[PtCl2(C4H7N2O2)2] (12). Anal. Calcd for C8H14N4Cl2O4Pt: C, 19.4;
H, 2.8; N, 11.3; Cl, 14.3; Pt, 39.3. Found: C, 18.9; H, 2.6; N, 10.8;
Cl, 14.0; Pt, 39.3. FAB+-MS, m/z: 425, [M - 2Cl]+. This compound
has no characteristic melting point. On heating, it decomposes above
ca. 240 °C. TLC on SiO2, Rf ) 0.68 (eluent Me2CO:CHCl3 ) 1:1,
v/v). IR spectrum (selected bands), cm-1: 3327 s ν(O-H), 1594 w
1
m ν(N-H), 1657 s and 1633 vs ν(CdN), 1184 s ν(SdO). H NMR
spectrum of both isomers in an approximate ratio 1:1 in CDCl3, δ:
2.72 (s, 6H, dC(Me)O), 1.65 (m, 4H), 1.72 (m, 8H), 2.37 (m, 4H) and
2.57 (m, 4H) (C5H10), 3.69 (s, 6H, Me2SO; value of JPtH was not
determined due to overlapping of the signals), 3.71 (s, 6H, Me2SO;
value of JPtH was not determined due to overlapping of the signals),
8.38 (s, br, 1H, NH), 8.60 (s, br, 1H, NH). 13C{1H} NMR spectrum of
both isomers in CDCl3, δ: 18.4 (NdC(Me)O), 25.0, 25.7, 26.7, 27.4
and 31.9 (C5H10), 40.5 (2JPtC 30 Hz) and 41.9 (2JPtC 28 Hz)(Me2SO),
169.0 (CdN(C5H10)), 174.6 (HNdC). 195Pt NMR spectrum in DMSO-
d6, δ: for the cis isomer -967 (400 Hz) and for the trans isomer -1080
1
ν(CdN). H NMR in DMSO-d6, δ: 2.44 (s).
[PtCl2(C6H9N2O2)2] (13). Anal. Calcd for C12H18N4Cl2O4Pt: C, 26.3;
H, 3.3; N, 10.2; Cl, 12.9; Pt, 35.6. Found: C, 26.4; H, 3.6; N, 10.3;
Cl, 12.6; Pt, 35.6. FAB+-MS, m/z: 477, [M - 2Cl]+. Mp: 185 °C.
TLC on SiO2, Rf ) 0.56 (eluent Me2CO:CHCl3 ) 3:2, v/v). IR spectrum
1
(selected bands), cm-1: 3433 vs, br ν(O-H), 1655 m-w ν(CdN). H
1
14
(t, JPt 200 Hz).
N
NMR in DMSO-d6, δ: 1.64 (m, 4 H), 2.83 (m, 4 H).
[PtCl4(NHdC(Me)ONdC(H)Ph)(Me2SO)] (10). The yield is 76%.
Anal. Calcd for C11H16N2Cl4O2PtS: C, 22.9; H, 2.8; N, 4.9; Cl, 24.6;
Pt, 33.8. Found: C, 22.5; H, 3.1; N, 4.8; Cl, 24.5; Pt, 33.5. FAB+-MS,
m/z: 529, [M - 2Cl + Na]+. Mp: 133 °C. TLC on SiO2, Rf ) 0.66
[PtCl2(C7H11N2O2)2] (14). Anal. Calcd for C14H22N4Cl2O4Pt: C,
29.1; H, 3.9; N, 9.7; Cl, 12.3; Pt, 33.9. Found: C, 29.3; H, 3.7; N, 9.4;
Cl, 12.4; Pt, 34.0. FAB+-MS, m/z: 506, [M - 2Cl]+. Mp: 200 °C
(dec). TLC on SiO2, Rf ) 0.55 (eluent CHCl3). IR spectrum (selected
(eluent acetone:CHCl3 ) 1:1, v/v). IR spectrum (selected bands), cm-1
:
1
bands), cm-1: 3437 vs, br ν(O-H), 1652 m-w ν(CdN). H NMR in
3005 w and 2918 w-m ν(N-H), 1665 s ν(CdN), 1623 m-s ν(CdC),
DMSO-d6, δ: 1.58 (m, 4 H), 1.74 (m, 2 H), 3.02 (m, 4 H).
1
1171 s ν(SdO), 764 m-s δ(C-H). H NMR spectrum in CDCl3, δ:
[PtCl2(C8H13N2O2)2] (15). Anal. Calcd for C16H26N4Cl2O4Pt: C,
31.8; H, 4.3; N, 9.3; Cl, 11.7; Pt, 32.3. Found: C, 32.1; H, 4.0; N, 9.7;
Cl, 12.3; Pt, 32.0. FAB+-MS, in NBA matrix, m/z: 533, [M - 2Cl]+.
Mp: 230 °C. IR spectrum (selected bands), cm-1: 3442 vs, br ν(O-
H), 1655 m-w ν(CdN). 1H NMR in DMSO-d6, δ: 1.47 (m, 4H), 1.64
(m, 4H), and 2.96 (m, 4H).
4
3
2.83 (s + d, JPtH 3.7 Hz, 3H, dC(Me)O), 3.78 (s + d, JPtH 14.5 Hz,
6H, Me2SO), 7.52 (m, 2H), 7.59 (m, 1H), and 7.76 (m, 2H) (Ph), 8.58
(s, 1H, dCH), 6.00 (s, br, 1H, NH). 13C{1H} NMR spectrum in CDCl3,
δ: 18.2 (NdC(Me)O), 40.4 (2JPtC 29 Hz, Me2SO), 128.8, 128.9, 129.4
and 133.1 (Ph), 157.3 (dCH), 171.4 (HNdC). 195Pt NMR spectrum in
1
14
DMSO-d6, δ: -978 (t, JPt 240 Hz).
N
X-ray Structure Determinations of [PtCl4(NHdC(Me)ONdC-
(Me)C(Me)dNOH)2]‚2DMF (1a) and [PtCl2(C8H13N2O2)2] (15).
Yellow needlelike crystals of 1a were grown from DMF (see above)
while yellow prisms of 15 were obtained directly from the reaction
mixtures. Diffraction data were collected on an Enraf-Nonius CAD 4
diffractometer (Mo KR radiation, â-filter). Cell parameters for the
complexes were obtained from 24 centered reflections with θ between
10 and 13° for both complexes. Data collection has been done with 2θ
between 2.3 and 25°. Range of hkl: h ) 0 to 8, k ) -9 to 9, l ) -16
to 16 for 1a, and h ) -8 to 9, k ) 0 to 9, l ) -10 to 11 for 15.
Standard reflections were measured every 60 min and showed practi-
cally no change with time ((1%). Diffractometer data were processed
by the program PROFIT41 with profile analysis of reflections. The
structures were solved by means of Fourier syntheses based upon the
Pt-atom coordinates obtained from the Patterson synthesis using the
SHELXTL package.42 After that, all reflections with I e 2σ(I) were
excluded from calculations. Refinement was done by full-matrix least
squares based on F2 using the SHELXL-97 package.43 All non-H atoms
were treated anisotropically. An extinction correction has been applied.
Lorenz, polarization, and absorption correction were made.44 Crystal
size: 0.42 × 0.34 × 0.09 mm for 1a and 0.33 × 0.32 × 0.13 mm for
15. Tmax and Tmin are 0.674 and 0.238 for 1a and 0.420 and 0.162 for
15. Scattering factors are from ref 45. Crystal data are given in Table
1, and bond distances and angles are in Tables 2 and 5.
[PtCl4(NHdC(Me)ONdC(H)C6H4(OH))(Me2SO)] (11). The yield
is 85%. Anal. Calcd for C11H16N2Cl4O3PtS: C, 22.3; H, 2.7; Cl, 23.9;
N, 4.7; Pt, 32.9. Found: C, 22.0; H, 2.6; Cl, 23.4; N, 4.5; Pt, 33.1.
FAB+-MS, m/z: 545, [M - 2Cl + Na]+. The complex has no
characteristic melting point. On heating it decomposes above 170 °C.
TLC on SiO2, Rf ) 0.43 (eluent acetone:CHCl3 ) 1:6). IR spectrum
(selected bands), cm-1: 3463 m ν(O-H), 3015 w and 2912 w ν(N-
H), 1661 vs ν(CdN), 1619 s ν(CdC), 1165 vs ν(SdO), 772 m-s δ-
(C-H). 1H NMR spectrum in acetone-d6, δ: 2.76 (s + d, 4JPtH 3.8 Hz,
3
3H, dC(Me)O), 3.80 (s + d, JPtH 15.4 Hz, 6H, Me2SO), 6.97 (d, 7.5
Hz, 1H), 7.03 (t, 8.4 Hz, 1H), 7.46 (ddd, 8.8 Hz, 7.3 Hz, 1.6 Hz, 1H),
7.76 (dd, 8.1 Hz, 1.9 Hz, 1H)(C6H4OH), 9.04 (s, 1H, dCH), 8.47 (s,
br, 1H, NH). 13C{1H} NMR spectrum in acetone-d6, δ: 18.3 (Nd
C(Me)O), 44.5 (2JPtC 28 Hz, Me2SO), 117.4, 121.1, 129.0, 132.6, 135.5,
and 155.5 (C6H4OH), 155.8 (dCH), 175.4 (HNdC). 195Pt NMR
1
14
spectrum in DMSO-d6, δ: -879 (t, JPt 280 Hz).
N
Reaction of [PtCl4(MeCN)(Me2SO)] with Dioximes. The solid
oxime (0.9 mmol) is added to a solution of [PtCl4(MeCN)(Me2SO)]
(0.1 g, 0.36 mmol) in acetonitrile (7 mL) on stirring at 50-60 °C.
After completion of homogenization (ca. 1-2 min) the solution became
darker. In the case of cyclohexanedione dioxime a green precipitate of
[Pt(C6H9N2O2)2] started to release. The precipitate is filtered off, and
the filtrate is left to stand for 1 d at room temperature whereafter
released dark-orange crystals of [PtCl2(C6H9N2O2)2] (13) are collected
on a filter. In the case of dimethylglyoxime, the compounds of platinum-
(II) and platinum(IV), e.g. [Pt(C4H7N2O2)2] and [PtCl2(C4H7N2O2)2]
(12), precipitated together after approximately 1 week from the mixing
the reagents. These two precipitates were separated mechanically. In
the two other cases (cycloheptane and cyclooctanedione dioximes)
formation of [Pt(dioximato)2] was not observed and only the platinum-
(IV) compounds [PtCl2(dioximato)2] (14, 15) were isolated from the
reaction mixtures.
(41) Strel’tsov, V. A.; Zavodnik, V. E. Kristallografia 1989, 34, 1369.
(42) Sheldrick, G. M. SHELXTL User Manual, ReV. 3; Nicolet XRD
Corp.: Madison, WI, 1981.
(43) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen: Go¨ttingen,
Germany.
(44) Axelrud, L. G.; Grin, Yu. N.; Zavalii, P. Yu.; Pecharsky, V. K.;
Fundamensky, V. S. CSD-universal program package for single crystal
and/or powder structure data treatment. Collected Abstracts, XIIth
European Crystallographic Meeting, Moscow, Aug 1989; USSR
Academy of Sciences: Moscow, 1989; p 155.
(45) International Tables for X-ray Crystallography; Kynoch Press: Bir-
mingham, U.K., 1974, Vol. IV.
Reaction of [PtCl4(Me2SO)2] with Dioximes. The oxime (0.63
mmol) is added to a solution of [PtCl4(Me2SO)2] (0.15 g, 0.30 mmol)
in acetonitrile (7-10 mL) at room temperature, and then the mixture

220 Inorganic Chemistry, Vol. 39, No. 2, 2000
Kukushkin et al.
Table 1. Crystallographic Data for [PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2]‚2DMF (1a), [PtCl4(NHdC(Me)ONdC{C4H8}CdNOH)2]
(4), [PtCl2(C7H11N2O2)2] (14), and [PtCl2(C8H13N2O2)2] (15)
1a
4
14
15
empirical formula
fw
C18H36N8Cl4O6Pt
797.44
C16H22N6Cl4OPt
699.28
20(2)
C14H22N4Cl2O4Pt
576.34
20(2)
C16H26N4Cl2O4Pt
604.40
temp, °C
λ, Å
20(2)
20(2)
0.710 73
P1h (No. 2)
6.9010(10)
8.303(2)
14.177(3)
101.02(3)
99.35(3)
96.68(3)
777.6(3)
1
0.710 69
P21/c (No. 14)
10.290
18.153
13.059
90
0.710 69
P21/n (No. 14)
8.163(3)
7.823(3)
14.51(4)
90
0.710 73
P1h (No. 2)
7.670(2)
8.230(2)
9.682(2)
65.14(3)
86.18(3)
65.12(3)
498.5(2)
1
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
94.46
90
100.04(3)
90
2431.96
4
912(3)
Z
2
F
calcd, g/cm3
1.703
1.915
2.098
2.013
µ(Mo KR), cm-1
48.99
65.42
80.08
73.3
a
R1
wR2
0.0263
0.058
0.0412
0.1117
0.0264
b
0.066
0.078
0.0747
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo )2]]1/2
.
2
2
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
[PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2]‚2DMF (1a)a
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
[PtCl2(C7H11N2O2)2] (14)a
Pt-N(1)
2.013(3)
2.3098(13)
2.3161(13)
1.347(5)
1.426(5)
1.385(6)
1.261(6)
1.278(6)
1.284(6)
C(1)-C(6)
C(2)-C(3)
C(2)-C(4)
C(3)-C(5)
O(3)-C(7)
N(4)-C(7)
N(4)-C(9)
N(4)-C(8)
1.484(7)
1.469(7)
1.496(7)
1.498(8)
1.215(8)
1.301(8)
1.432(8)
1.448(8)
Pt-Cl
2.312(7)
1.998(7)
2.000(7)
1.321(8)
1.349(8)
N(1)-C(2)
N(2)-C(1)
C(1)-C(2)
C(1)-C(3)
C(2)-C(7)
1.318(7)
1.300(7)
1.470(9)
1.487(8)
1.491(9)
Pt-Cl(1)
Pt-N(1)
Pt-N(2)
O(1)-N(1)
O(2)-N(2)
Pt-Cl(2)
O(1)-C(1)
O(1)-N(2)
O(2)-N(3)
N(1)-C(1)
N(2)-C(2)
N(3)-C(3)
Cl-Pt-N(1)
Cl-Pt-N(2)
Cl-Pt-N(1)*
Cl-Pt-N
N(1)-Pt-N(2)
Cl-Pt-N
89.77(17)
88.19(17)
90.23(17)
91.81(17)
78.50(19)
90.23(17)
101.50(19)
91.81(17)
101.50(19)
89.77(17)
88.19(17)
78.50(19)
Pt-N(1)-O(1)
118.7(3)
116.6(4)
124.6(5)
120.1(3)
117.1(4)
122.7(4)
113.9(4)
123.1(5)
123.0(4)
113.7(4)
123.4(5)
122.9(4)
Pt-N(1)-C(2)
O(1)-N(1)-C(2)
Pt-N(2)-O(2)
N(1)-Pt-Cl(1)
N(1)-Pt-Cl(2)*
Cl(1)-Pt-Cl(2)*
Cl(1)-Pt-Cl(2)
C(1)-O(1)-N(2)
C(1)-N(1)-Pt
94.34(11)
93.80(11)
90.52(6)
89.48(6)
111.7(3)
136.0(3)
110.9(4)
111.9(5)
122.2(4)
N(1)-C(1)-C(6)
O(1)-C(1)-C(6)
N(2)-C(2)-C(3)
N(2)-C(2)-C(4)
C(3)-C(2)-C(4)
N(3)-C(3)-C(2)
N(3)-C(3)-C(5)
C(2)-C(3)-C(5)
127.2(4)
110.6(4)
113.3(4)
124.9(4)
121.7(4)
114.9(5)
125.2(5)
119.9(4)
Pt-N(2)-C(1)
O(2)-N(2)-C(1)
N(2)-C(1)-C(2)
N(2)-C(1)-C(3)
C(2)-C(1)-C(3)
N(1)-C(2)-C(1)
N(1)-C(2)-C(7)
C(1)-C(2)-C(7)
N(1)-Pt-N
Cl-Pt-N(2)
N(1)*-Pt-N(2)
Cl-Pt-N(1)*
Cl-Pt-N
C(2)-N(2)-O(1)
C(3)-N(3)-O(2)
N(1)-C(1)-O(1)
N(1)*-Pt-N
a Symmetry transformations used to generate equivalent atoms: *,
-x, -y, -z.
a Symmetry transformations used to generate equivalent atoms: *,
-x +1, -y + 1, -z + 1.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
[PtCl4(NHdC(Me)ONdC{C4H8}CdNOH)2] (4)
Table 5. Selected Bond Lengths (Å) and Angles (deg) for
[PtCl2(C8H13N2O2)2] (15)a
Pt-Cl(2)
2.307(7)
2.312(6)
2.315(6)
2.332(6)
2.048(17)
2.029(17)
1.47(2)
O(29)-N(21)
N(7)-C(16)
N(18)-C(14)
N(20)-C(23)
N(21)-C(42)
N(26)-C(9)
N(55)-C(13)
C(9)-C(23)
C(13)-C(25)
C(14)-C(42)
C(16)-C(34)
1.41(3)
1.30(3)
1.28(2)
1.27(3)
1.30(4)
1.25(4)
1.27(3)
1.51(3)
1.50(3)
1.45(3)
1.49(3)
Pt-Cl(3)
Pt-N(2)
Pt-N(1)
Pt-Cl
1.989(5)
2.002(5)
2.3067(19)
1.296(7)
1.357(7)
N(1)-C(1)
N(2)-C(8)
C(1)-C(8)
C(1)-C(2)
C(7)-C(8)
1.308(9)
1.293(8)
1.456(9)
1.504(8)
1.498(9)
Pt-Cl(4)
Pt-Cl(5)
Pt-N(7)
O(1)-N(1)
O(2)-N(2)
Pt-N(55)
O(11)-N(18)
O(11)-C(13)
O(12)-N(20)
O(12)-C(16)
O(17)-N(26)
N(2)-Pt-N(1)*
N(2)-Pt-N(1)
N(2)-Pt-Cl
101.4(2)
78.6(2)
N(1)-C(1)-C(2)
C(8)-C(1)-C(2)
C(8)-N(2)-Pt
121.8(6)
123.9(6)
116.9(4)
122.2(4)
114.3(5)
114.3(5)
122.8(6)
122.7(6)
1.36(3)
1.45(2)
90.65(17)
89.35(18)
125.5(5)
118.6(4)
115.9(4)
120.9(5)
1.35(3)
N(1)*-Pt-Cl
O(2)-N(2)-Pt
1.43(2)
O(1)-N(1)-C(1)
O(1)-N(1)-Pt
C(1)-N(1)-Pt
C(8)-N(2)-O(2)
N(1)-C(1)-C(8)
N(2)-C(8)-C(1)
N(2)-C(8)-C(7)
C(1)-C(8)-C(7)
Cl(2)-Pt-Cl(3)
Cl(2)-Pt-Cl(4)
Cl(2)-Pt-Cl(5)
Cl(2)-Pt-N(7)
Cl(2)-Pt-N(55)
Cl(3)-Pt-Cl(4)
Cl(3)-Pt-Cl(5)
Cl(3)-Pt-N(7)
Cl(3)-Pt-N(55)
Cl(4)-Pt-Cl(5)
Cl(4)-Pt-N(7)
Cl(4)-Pt-N(55)
Cl(5)-Pt-N(7)
Cl(5)-Pt-N(55)
N(7)-Pt-N(55)
90.3(2)
91.0(2)
89.7(2)
92.0(5)
174.2(6)
177.6(2)
90.3(2)
93.7(5)
94.1(5)
91.7(2)
84.3(5)
84.5(5)
175.7(5)
94.1(5)
84.0(7)
O(12)-N(20)-C(23) 110.5(15)
O(29)-N(21)-C(42) 116(2)
O(17)-N(26)-C(9)
Pt-N(55)-C(13)
112.7(19)
137.1(16)
113(2)
a Symmetry transformations used to generate equivalent atoms: *,
-x + 1, -y + 1, -z + 1.
N(26)-C(9)-C(23)
N(26)-C(9)-C(40)
128(2)
N(55)-C(13)-C(25) 125.0(19)
N(18)-C(14)-C(37) 124.0(19)
N(18)-C(14)-C(42) 116.6(19)
N(18)-C(14)-C(42) 116.6(19)
reaction mixtures and before the data collection were studied in the
Weissenberg camera. Diffraction data were collected on a Syntex P21
diffractometer (Mo KR radiation, graphite monochromator, ω-method).
Cell parameters for the complexes were obtained from 15 centered
reflections with θ between 10 and 20°. Data collection has been done
with 2θ between 2 and 60° for 4 and 2 and 85° for 14. Range of hkl:
h ) 0 to 13, k ) 0 to 25, l ) -18 to 18 for 4, and h ) 0 to 16, k )
0 to 15, l ) -29 to 28 for 14. Standard reflections were measured
every 50 reflections and showed practically no change with time ((1%).
The structures were solved by means of Patterson method using the
CSD-universal program package.44 After that, all reflections with I <
3σ(I) were excluded from calculations. Lorenz, polarization, and
absorption correction were made.44 Crystal sizes: 0.1 × 0.1 × 0.2 mm
for 4, and 0.15 × 0.2 × 0.1 mm for 14. Tmax and Tmin are 1.328 and
O(12)-C(16)-N(7)
120.5(17)
O(12)-C(16)-C(34) 114.5(19)
N(7)-C(16)-C(34)
N(20)-C(23)-C(9)
125(2)
113(2)
N(20)-C(23)-C(22) 128(2)
N(18)-O(11)-C(13) 109.1(13) N(21)-C(42)-C(14) 117(2)
N(20)-O(12)-C(16) 111.8(15) N(21)-C(42)-C(50) 119(2)
Pt-N(7)-C(16)
138.4(15) O(11)-C(13)-N(55) 125.2(18)
O(11)-N(18)-C(14) 106.8(16) O(11)-C(13)-C(25) 109.8(17)
X-ray Structure Determination of [PtCl4(NHdC(Me)ONdC-
{C4H8}CdNOH)2] (4) and [PtCl2(C7H11N2O2)2] (14). Brownish-
yellow prismatic crystals of 4 and 14 were obtained directly from the

Formation of Pt(IV)-Based Metallaligands
Inorganic Chemistry, Vol. 39, No. 2, 2000 221
0.883 for 4 and 1.018 and 0.990 for 14. Atomic scattering factors are
from ref 45. Crystal data are given in Table 1, and bond distances and
angles, in Tables 3 and 4.
Calculations. The full geometry optimization of the structures was
carried out in Cartesian coordinate using the quasi-Newton-Raphson
gradient method and the restricted Hartree-Fock approximation with
the help of the GAMESS-97 package.46 Symmetry operations were not
applied. As quantum-chemical calculations of compounds with heavy
5d and 6d elements should use a relativistic quantum mechanic
approach, a quasi-relativistic pseudopotential for 60 core electrons and
the contracted basis set (8s7p6d)/[6s5p3d]47 for the platinum atom along
with the analogous pseudopotentials and basis sets (4s4p)/[2s2p] (C,
N) and (4s5p)/[2s3p] (O)48 for other non-hydrogen atoms have been
used. The standard basis set of Gauss functions 6-31G49 was selected
for hydrogen atoms.
Results and Discussion
Synthetic Experiments and Characterization of Products.
The experimental conditions for conducting the reaction between
the Vic-dioximes and trans-[PtCl4(RCN)2] (R ) Me, CH2Ph,
Ph, dioxime ) dimethylglyoxime; R ) Me, dioxime )
cyclohexa-, cyclohepta-, and cyclooctanedione dioximes) are
similar to the earlier described ones for the reaction between
trans-[PtCl4(RCN)2] with so-called “simple” oximes.2 Elemental
analyses (C, H, N, Cl, Pt) and FAB+ mass spectrometry data
(see Experimental Section) of products of the reaction suggest
addition of two molecules of the dioxime/one molecule of the
starting Pt(IV) material. IR spectra of the products show no
bands due to ν(CtN) vibrations (in the starting trans-[PtCl4-
(RCN)2] bands at 2354 cm-1 for R ) Me, 2337 cm-1 for R )
CH2Ph, and 2316 cm-1 for R ) Ph) but display ν(CdN) bands
(ca. 1665-1620 cm-1) along with rather weak bands in ranges
of 3225-3285 and 1140-1199 cm-1 which were attributed to
ν(N-H) and ν(C-Ã) stretching vibrations,50,51 respectively.
Concurrently, in all compounds bands due to ν(O-H) stretch
which emerge in range 3420-3450 cm-1 were detected.
Figure 2. ORTEP drawing of trans-[PtCl4(NHdC(Me)ONdC(Me)C-
(Me)dNOH)2]‚2DMF (1a) with atomic numbering scheme.
the case of [PtCl4(MeCN)2], the product 1 releases from the
reaction mixture as crystals which were subject to X-ray
structure determination. Unfortunately, a strong disorder of the
newly formed ligand prevented complete structure solution.
However, it was clear that these ligands are in trans positions
to each other. Recrystallization of thus prepared trans-1 from
dimethylformamide resulted in precipitation of the bis-solvate
trans-[PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2]‚2DMF (1a),
whose structure was successfully determined by X-ray single-
crystal diffraction (Figure 2, Tables 1 and 2).
The coordination polyhedron of the complex is a slightly
distorted octahedron and the Pt atom is in the center of
symmetry. The two iminoacylated ligands are in mutual trans
positions, and their oxime parts are in anti conformation. Two
OH groups are involved in strong8,52,53 intermolecular hydrogen
bonding [OH‚‚‚O distance is 1.877(7) Å, O‚‚‚O is 2.664(6) Å,
and O-H‚‚‚O angle is 161.25°] with two dimethylformamide
molecules. In the iminoacylated ligands, values of the two Cd
N bonds are almost identical and correspond to the mean values
of the CdN double bonds.54,55 All other bonds and angles are
normal and agree well with iminoacylated oxime2 and imino-
acylated diethylhydroxylamine platinum(IV)3 compounds previ-
ously characterized by some of us.
1
In H and 13C{1H} NMR, the iminoacylated ligands show
characteristic signals of the amidine carbon (average 174 ppm),
1
as well as for the methyl group (average 1.7 ppm in H and
average 18 ppm in 13C{1H} NMR). These mean values agree
well with those found for the previously described addition
products of the “simple” oximes.2 The two dioxime CdN groups
appear at different chemical shifts (average 165 ppm and average
154 ppm), thus indicating that only one of the oxime groups
was added to the nitrile. A difference in chemical shifts was
also observed for the alkyl substituents on the dioxime part,
which appear as individual signals due to the loss of symmetry.
For discussion of NMR spectroscopy data relevant to cis-trans
isomerization of the iminoacylated complexes, see below.
Reactions of trans-[PtCl4(RCN)2] (R ) Me, CH2Ph or Ph)
with Dimethylglyoxime and Cycloheptane- and Cyclooc-
tanedione Dioximes. The reactions proceed in good yield and
give [PtCl4(NHdC(R)ONdC(Me)C(Me)dNOH)2] (1-3). In
When the addition was performed starting from a mixture of
cis- and trans-[PtCl4(MeCN)2], formation of the two geometrical
isomers was observed and their interconversion was monitored
1
by H, 2D [1H,15N] HMQC, and 195Pt NMR spectroscopy in
DMSO-d6 solutions. Complex cis-1 (1H NMR spectrum, δ, 2.01
4
and 2.28 (two s, 3H each, dC(Me)C(Me)), 2.68 (s, JPtH was
not resolved, 3H, dC(Me)O), 9.19 (s + d, 2JPtH 23.7 Hz, NH),
12.43 (s, 1H, OH); 2D [1H,15N] HMQC NMR spectrum, δ,
104.5 (1JPtN was not resolved); 195Pt NMR spectrum, δ, 63 (320
Hz)) in DMSO-d6 solution at 20-25 °C for 3 d converts
completely to the trans isomeric form (1H NMR spectrum, δ,
(46) Schmidt, M. W.; Baldridge, K. K.; Boatz, J. A.; Elbert, S. T.; Gordon,
M. S.; Jensen, J. H.; Koseki, S.; Matsunaga, N.; Nguyen, K. A.; Su,
S. J.; Windus, T. L.; Dupuis, M.; Montgomery, J. A. J. Comput. Chem.
1993, 14, 1347.
(47) Andrae, D.; Haeussermann, U.; Dolg, M.; Stoll, H.; Preuss, H. Theor.
Chim. Acta 1990, 77, 123.
4
2.00 and 2.31 (two s, 3H each, dC(Me)C(Me)), 2.78 (s, JPtH
2
was not resolved, 3H, dC(Me)O), 8.87 (s + d, JPtH 33.2 Hz,
NH), 12.52 (s, 1H, OH); 2D [1H,15N] HMQC NMR spectrum,
(48) Bergner, A.; Dolg, M.; Kuechle, W.; Stoll, H.; Preuss, H. Mol. Phys.
1993, 80, 1431.
(49) Ditchfield, R.; Hehre, W. J.; Pople, J. A. J. Chem. Phys. 1971, 54,
724.
(52) Gilli, P.; Bertolasi, V.; Ferretti, V.; Gilli, G. J. Am. Chem. Soc. 1994,
116, 909.
(53) Kukushkin, V. Yu.; Tudela, D.; Izotova, Yu. A.; Belsky, V. K.; Stash,
A. I.; Polyhedron 1998, 17, 2455.
(50) Bellamy, L. J. The Infrared Spectra of Complex Molecules, 2nd ed.;
Methuen: London, 1996.
(51) Colthup, N. B.; Daly, L. H.; Wiberley, S. E. Introduction to Infrared
and Raman Spectroscopy; Academic Press: New York, 1964.
(54) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A.
G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.
(55) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.

222 Inorganic Chemistry, Vol. 39, No. 2, 2000
Kukushkin et al.
Scheme 3. Iminoacylation of Dimethylglyoxime and
Scheme 2. Cis-Trans Isomerization of
[PtCl4(NHdC(Me)ONdC(Me)C(Me)dNOH)2] (1)
Cyclooctanedione Dioxime To Give 1 and 6, Respectively
δ, 85.2 (1JPtN 363 Hz); 195Pt NMR spectrum, δ, -87 (550 Hz)).
2
Indeed, the larger value of JPtH for the NHdC hydrogen and
the value of 195Pt chemical shift of the latter complex are in
complete accord with the values found for the previously
described trans-Pt(IV) complexes containing iminoacylated
ligands.2 In contrast, the corresponding NMR data of the former
isomer are similar to values found for the structurally character-
ized cis-[PtCl4(NHdC(Me)ONdC{C4H8}CdNOH)2] (4) (see
below). The fact that the 195Pt NMR signal of the cis complex
appears downfield vs the corresponding trans isomer also agrees
well with the observations made for cis and trans isomeric
couple [PtCl4(Me2CdNOH)2].10 The 15N chemical shifts follow
a similar trend, and the cis isomer appears downfield vs the
trans one. To the best of our knowledge, detection of 15N
resonances for any platinum(IV) isomeric compounds is the first
observation of this kind.
Figure 3. ORTEP drawing of cis-[PtCl4(NHdC(Me)ONdC{C4H8}Cd
NOH)2] (4) with atomic numbering scheme.
appears at +76 ppm, i.e. about 150 ppm downfield of the
corresponding trans isomer.
On the basis of all the above listed data we suggest that the
isomerization is described by Scheme 2, where the cis form is,
similar to the complex cis-4 (see below), conditionally presented
in syn configuration of the oxime parts.
Surprisingly, in the reaction with cyclohexanedione dioxime
merely the cis isomer (cis-4) was isolated and identified (see
below). Reasons for the formation of the different isomers in
the reaction with the structurally similar dioximes are not yet
clear and probably deserve a separate study.
Cyclooctanedione dioxime reacts with trans-[PtCl4(MeCN)2]
similar to dimethylglyoxime (Scheme 3), and only the trans
isomer (trans-6) was isolated. Indeed, the amidine NH group
Reaction of trans-[PtCl4(MeCN)2] and Cyclohexanedione
Dioxime. Although the reaction with cyclohexanedione dioxime
visually proceeds analogously to those described for the other
dioximes, we were able to isolate and completely characterize
by physicochemical methods and by X-ray crystallography only
the cis isomer, i.e. cis-[PtCl4(NHdC(Me)ONdC{C4H8}Cd
1
2
in the H NMR spectrum shows a typical large JPtH (35 Hz)
and a 195Pt chemical shift of -78 ppm that agree well with
those found for trans-1 or previously described2 trans-imioacyl-
ated complexes.
Treatment of trans-[PtCl4(MeCN)2] with cycloheptanedione
dioxime gave a mixture of cis-5 and trans-5, but their inter-
conversion was not monitored due to decomposition of the
addition product in DMSO-d6 (the compound is not sufficiently
soluble in other most common solvents for NMR studies).
1
NOH)2] (4). The H NMR spectrum shows one amidine NH
2
signal with JPtH of 23 Hz, whereas the 195Pt signal appears at
57 ppm. These values are in good agreement with those
observed for the complexes cis-1 and cis-5. Unfortunately, the
compound is not enough stable in DMSO-d6 and not sufficiently
soluble in other solvents to study whether the isomerization
occurs.
1
Although the H and 13C{1H} chemical shifts for the cis and
trans isomers are very similar, the signal of the NH group allows
for assignment. In complete accordance with the reaction of
dimethylglyoxime, the cis isomer exhibits a higher chemical
The structure of 4 consists of an octahedrally coordinated
platinum(IV) center in which the two cis positions are filled
with newly formed iminoacylated cyclohexadioxime ligands
(Figure 3, Tables 1 and 3).
2
shift for the NH hydrogen, and the coupling constant JPtH is
smaller (23.4 Hz) than for the corresponding trans isomer (2JPtH
32.3 Hz). In 195Pt NMR, the signal of the trans compound (-72
ppm) lies in a similar range as for the previously described
“simple” oxime addition products,2 whereas the cis compounds
The Pt-Cl bond lengths [2.307(7)-2.332(6) Å] are of normal

Formation of Pt(IV)-Based Metallaligands
Inorganic Chemistry, Vol. 39, No. 2, 2000 223
values.56-58 All six CdN bonds [1.25(4)-1.30(3) Å] and the
four N-O bonds [1.41(3)-1.47(2) Å] are equal within 3σ, and
these distances agree with the mean values of the CdN and
the N-O bonds, correspondingly.2,3,54,55 Apparently, the most
interesting feature of cis-4 is the existence of a potentially
multidentate Pt(IV)-based metallaligand that consists of the
platinum atom and the two adjacent iminoacylated species.
Within the NHdC(Me)ONdC{C4H8}CdNOH ligands, the
imino hydrogens [HN(55) and HN(7)] are involved in intramo-
lecular hydrogen bonding with the neighboring nitrogens N(18)
and N(20), respectively. Distances N(55)‚‚‚N(18) (2.596 Å) and
N(7)‚‚‚N(20) (2.559 Å) are similar to those in the previously
reported structures of trans-[PtCl4(NHdC(Me)ONCR1R2)2] and
trans-[PtCl4(NHdC(Me)ONEt2)2] (2.59-2.60 Å2,3), where the
same type of H-bond was unambiguously detected. Although
we were unable to refine hydrogen atoms on the OH groups, a
relatively short O(29)‚‚‚O(17) distance (3.12 Å) indicates this
type of bonding. Appearance of a broad signal of O-H
stretching frequencies in the IR spectra of the addition products
which emerges in a range 3420-3450 cm-1 also suggests a
hydrogen bond, albeit weak.50,51
Geometrical Isomerism and Isomerization. For better
understanding of the geometrical isomerism for the platinum-
(IV) iminoacylated complexes we have calculated the equilib-
rium geometry and the relative stability for the molecules and
fragments with structures similar to cis-4 but without a
possibility to form intramolecular hydrogen bonds of the above-
mentioned type. Thus, the influence of the H-bond on the
stability of the cis conformation was excluded. For the calcula-
tions, we addressed cis- and trans-[PtCl4(NHdC(Me)ONd
CMe2)2]. The X-ray structure of the latter isomer (I) (Figure 4)
was reported earlier by some of us,2 and these data were taken
as the starting geometry for the model simplified trans structure
(II) and as initial geometry parameters of oxime ligands for
the model cis isomer (III), where the methyl groups were
displaced by hydrogen atoms for simplicity reasons. Since X-ray
data for cis-[PtCl4(NHdC(Me)ONdCMe2)2] are unavailable,
several initial conformations of III, which differ by the
orientation of the oxime ligands relative to the Pt-N bond, have
been used.
To justify the chosen model structures, the full geometry
optimization of I has also been carried out. The calculated
geometry parameters for the simplified model structure and the
real one appeared to be very similar, e.g. the maximum
difference for bond lengths is 0.017 Å, whereas the maximum
deviation of bond angles is 8.7° for Pt-N-C and not more
than 4.6° for the other ones. The significant difference for the
Pt-N-C angles is probably due to the steric hindrance of the
methyl group. Taking into account well-coherent calculated
geometrical parameters for both I and II, the geometry
optimization of the cis conformation (III) was performed only
for the simplified model molecule.
Figure 4. Models used for calculations.
0.089 Å for the Pt-Cl bonds and is not higher than 0.025 Å
for other bonds of both I and II. The maximum difference for
bond angles is 8.9° for II (the Pt-N-C angle) and 2.2° for I
(the O-N-C angle). The intramolecular N-H‚‚‚N hydrogen
bond that stabilizes the general conformation of oxime ligands
can be suggested on the basis of interatomic distances (the
calculated distances for N(7)‚‚‚N(8), N(7)-H, and N(7)H‚‚‚
N(8) are 2.63, 1.00, and 2.15 Å, respectively, and the angle
N-H‚‚‚N is 107.7° for I; they are 2.69, 1.00, and 2.32 Å and
100.7° for II, correspondingly). However their calculated
parameters differ from the experimental ones (the corresponding
values are 2.605, 0.74, and 2.20 Å and 115°). It is well-known
that X-ray diffraction often gives shorter distances for E-H
bonds than distances determined by neutron diffraction because
the location of the hydrogen atoms electron cloud is different
from the positions of the hydrogen nucleus,8,59 and this might
be the reason of the disagreement between experimental and
calculated parameters of the H-bonds.
Three equilibrium structures with very similar energies (the
most stable of these structures is marked as III), differing only
by the conformations of the oxime ligands, have been obtained
for the cis isomer. The torsion angles NPtNC for these structures
are -51.0 and -51.5°, 52.9 and -53.6°, and 51.5 and 51.0°.
Other geometrical parameters exluding the angles N-Pt-Cl and
Cl-Pt-Cl are almost the same for these conformations and very
similar to the corresponding parameters of II. The most
noticeable difference was observed for the Pt-N bonds (2.035
The general calculated conformation of I and II corresponds
well to the X-ray structure of trans-[PtCl4(NHdC(Me)ONd
CMe2)2], even taking into account orientations of the methyl
groups. Calculated bond lengths and angles are also in good
agreement with the experimental parameters, except for the Pt-
Cl bonds, e.g. the maximum bond length difference consists
(56) Kukushkin, V. Yu.; Zenkevich, I. G.; Belsky, V. K.; Konovalov, V.
E.; Moiseev, A. I.; Sidorov, E. O. Inorg. Chim. Acta 1989, 166, 79
and references therein.
(57) Ryabov, A. D.; Kazankov, G. M.; Panyashkina, I. M.; Grozovsky, O.
V.; Dyachenko, O. G.; Polyakov, V. A.; Kuzmina, L. G. J. Chem.
Soc., Dalton Trans. 1997, 4385.
(58) Galanski, M.; Keppler, B. K. Inorg. Chim. Acta 1997, 265, 271.
(59) Desiraju, G. R. Acc. Chem. Res. 1996, 29, 441.

224 Inorganic Chemistry, Vol. 39, No. 2, 2000
Kukushkin et al.
Å for II and 2.058 Å for III) and for the Pt-Cl bonds which
are in the trans position to the oxime ligands (2.389 Å for II
and 2.371 Å for III), probably reflecting the higher ground-
state trans influence of chloride compared with the iminoacyl-
ated oxime ligand. The conformation of the oxime ligands is
also stabilized by intramolecular hydrogen bonds [N(7)‚‚‚N(8),
N(7)-H, and N(7)H‚‚‚N(8) of 2.70, 1.00, and 2.32 Å and N-H‚
‚‚N of 101.0°].
The energy difference between the trans conformation and
the most stable of three calculated cis conformation is 7.96 kcal/
mol (the full energy is -274.273 34 hartree for the structure II
and -274.260 66 hartree for the structure III).
Figure 5. ORTEP drawing of [PtCl2(C7H11N2O2)2] (14) with atomic
numbering scheme.
Thus, the calculations showed that for the iminoacylated
dioxime complexes of platinum(IV) which do not contain
intramolecular hydrogen bonds between two oxime ligands, the
trans isomers are more stable than cis isomers. Derivatization
by introducing substituents that can form intramolecular hy-
drogen bonds of such type leads to increase of the relative
stability of the cis isomer. These facts are indirect arguments
in favor of the additional stabilization of cis isomer of 4 by the
H-bond between the two peripherical OH groups.
The calculations agree well with experimental observations.
Indeed, when “simple” oximes reacted with trans-[PtCl4-
(MeCN)2] the iminoacylation always led to complexes of the
trans configuration.2 Moreover, on the basis of massive experi-
mental data, it was declared as a general statement that namely
the trans form is the more stable one for metal complexes
(including platinum(IV) compounds60-65) in high oxidation
states.66 Formation of relatively stable cis isomer in the case of
complexes with iminoacylated Vic-dioximes is probably due to
the hydrogen bond between the two OH groups that “sew” the
two iminoacyl arms.
Formation of the Substitution Products [PtCl2(dioximato)2]
(13-15) in the Course of the Iminoacylation and X-ray
Structures of [PtCl2(C7H11N2O2)2] (14) and [PtCl2(C8-
H13N2O2)2] (15). In the course of the iminoacylation we also
isolated the products which formed due to a substitution process,
e.g. compounds [PtCl2(dioximato)2] (13-15) (where dioximato
) monodeprotonated cyclohexa-, cyclohepta-, or cyclooctanedi-
one dioxime); the complex of this type was not observed in the
case of dimethylglyoxime. In fact, the substitution products are
formed in such a low yields that we succeded only in mechanical
separation of their crystals from crystals of the addition products
exhibiting different shape. However, the amount of the materials
thus obtained was sufficient for their characterization by both
analytical and spectroscopic methods. Structures of the two
compounds, [PtCl2(C7H11N2O2)2] (14) and [PtCl2(C8H13N2O2)2]
(15), were determined by X-ray single-crystal diffraction. The
coordination polyhedron of both complexes is a slightly distorted
octahedron (Figures 5 and 6, Tables 1, 4, and 5).
Figure 6. ORTEP drawing of [PtCl2(C8H13N2O2)2] (15) with atomic
numbering scheme.
2.307(2) Å in 15] agree well with those of previously character-
ized platinum(IV) chloride compounds,56-58 and the Pt-N and
NdC distances are of normal values.54,55 In 15, where hydrogen
atoms on the OH groups were found from difference syntheses
and were refined, it is clearly seen that the oxime and oximato
parts of the ligands form six-membered rings involving in-
tramolecular hydrogen bonds [O(1)‚‚‚O(2*), 2.681(9) Å; O(1)‚
‚‚H-O(2*), 142(13)°]. As expected for the negative charge
assisted hydrogen bonding,52 these distances are in the range
of strong hydrogen bonds.8,67,68 Since the structure of 15 contains
both the oxime and oximato parts of the chelating ligands, the
N-O(oximato) distance [1.296(7) Å] is reasonably shorter than
the N-O(oxime) one [1.357(7) Å]. The same trend in the N-O
bond lengths was observed in 14 although H-atoms on the OH
groups were not located. Despite the traditional coordination
mode of the oxime ligands, these two complexes are the first
example of structurally characterized derivatives of platinum-
(IV) with Vic-dioximes. Previously only complexes of both
platinum(II)69-80 and platinum(III)81,82 that contain dioximes
were subject of crystallographic studies.
Dioximato ligands in the structures are in trans configuration.
The values of the Pt-Cl bond distances [2.312(7) in 14 and
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A.; Kozlowski, H.; Sliva, T. Yu.; Swiatek-Kozlowska, J. J. Chem.
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Chem. (Engl. Transl.) 1988, 33, 1085.

Formation of Pt(IV)-Based Metallaligands
Inorganic Chemistry, Vol. 39, No. 2, 2000 225
Concluding Remarks
The complexes 13-15 and [PtCl2(C4H7N2O2)2] (12) (C4H7N2O2
is the monodeprotonated dimethylglyoxime) were also obtained
in a reasonable yield on treatment of either [PtCl4(Me2SO)2] or
[PtCl4(MeCN)(Me2SO)] with 2 equiv of the dioxime. However,
in these two cases the substitution was accompanied by
reduction of the central ionsprobably by the released dimethyl
sulfoxide83-87sand this led to contamination of 12-15 with
the well-known platinum(II) complexes [Pt(dioximato)2].88,89
Reactions of [PtCl4(MeCN)(Me2SO)] with “Simple” Oximes.
For comparative reasons, it is worthwhile to mention that the
reaction between [PtCl4(MeCN)(Me2SO)] and the Vic-dioximes
proceeds in a different direction than that, which was also
investigated in this study, for this complex and “simple” oximes
(Me2CdNOH, {C4H8}CdNOH, {C5H10}CdNOH, PhC(H)d
NOH) and even salicylaldoxime, (OH)C6H4C(H)dNOH (for the
relevant reaction see Scheme 1). In the latter case the addition
of the oximes to the ligated acetonitrile was observed, leading
to the iminoacylated species [PtCl4(NHdC(Me)ONdCRR′)-
(Me2SO)] (7-11) (RR′ ) Me2, {C4H8}, {C5H10}, Ph(H), (OH)-
C6H4(H)) which exist as a mixture of cis and trans isomers.
To the best of our knowledge, all known metallaligands were
previously prepared by direct addition of ligands to metal-
containing precursors. In our case, the dioxime part of the
metallaligand was created in the course of the addition of
reagents to coordinated organonitriles which are activated by
the metal center. It is also noteworthy to mention that, despite
the variety of products that might be expected to be formed in
these reactionssin view of the usability of dioximes as ligandss
our system presents a remarkable selectivity toward the nu-
cleophilic addition of one oxime moiety of each dioxime to each
of the nitrile ligands to form an unusual arrangement of two
iminoacyl ligands that interact, by hydrogen bond, through their
terminal unreacted oxime groups which, thus, are not simple
spectators and play a significant role in the stabilization of the
unexpected final product. Hence, within the various factors that
drive the observed reaction, the relevance of the hydrogen bond
appeared to be evident. This ability of hydrogen bonding to
stabilize unusual structures derived from dioxime reactions
should be explored further. Moreover, our reaction might be
useful for the preparation of a broad spectrum of Pt(IV)-based
metallaligands since a variety of dioximes and other bidentate
ligands that contain the N-OH moiety are either comercially
available or well described in the literature.
1
The iminoacylated ligands display a similar H and 13C{1H}
spectra for both isomers. However, the presence of two
compounds is shown by their distinct NH proton resonances
(average 8.4 ppm for the cis isomers vs average 8.6 ppm for
the trans isomers).
In contrast to the iminoacylated ligand, the coordinated
dimethyl sulfoxide appears as two distinct signals in 1H as well
as in 13C{1H}, both showing coupling to platinum (3JPtH and
2JPtC). This observation suggests that in both complexes the Me2-
SO is coordinated via its sulfur. According to the previously
described starting material,37 the signals with lower proton
chemical shift and larger JPtH (typically ca.15.0 Hz for cis
isomers vs ca.13.5 Hz for trans ones) and smaller carbon
chemical shift and smaller JPtC (typically ca. 28 Hz for cis
isomers vs ca. 32 Hz for trans ones) are assigned to the cis
isomer.
We hope that the results reported in this article contribute to
the chemistry of Vic-dioximes considerably, and we will continue
these investigations in depth. Further synthetic studies are now
in progress to establish, on one hand, a potential of the
discovered type of metallaligands for further complexing and,
on the other hand, to extend the iminoacylation reactions to
other high-valent metal complexes including, in particular,
rhodium(III)90 and rhenium(IV)91 compounds.
Acknowledgment. V.Yu.K. is very much obliged to the
Russian Fund for Basic Research (Grant 97-03-33626a) and the
PRAXIS XXI program (Grant BCC16428/98) for financial
support of this study. T.B.P. expresses her gratitude to the Soros
Foundation for a fellowship (a98-230). A.J.L.P. thanks the FCT
(Foundation for Science and Technology) and the PRAXIS XXI
program for financial support. G.W. and M.L.K. are grateful to
the PRAXIS XXI program for a fellowship (BPD11779/97 and
BPD16369/98). We also thank Profs. A. I. Dement’ev and N.
S. Panina for valuable discussions relevant to this work. The
authors are indebted to Profs. V. K. Belsky and V. S.
Fundamensky for X-ray diffraction analyses and Y. Z. Voloshin
for a generous gift of cycloheptanedione and cycloctanedione
dioximes.
In 195Pt NMR, both isomers show clearly separate signals,
i.e. the cis isomer appearing at ca. -970 ppm whereas the trans
isomer resonates at around -1080 ppm. It is worthwhile to
mention that for most compounds the coupling between platinum
and 14N could be resolved, thus leading to a triplet structure of
1
14
the platinum signal with a typical JPt of 200 to 260 Hz.
N
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Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of [PtCl4(NHdC(Me)-
ONdC(Me)C(Me)dNOH)2]‚2DMF (1a), [PtCl4(NHdC(Me)ONd
C{C4H8}CdNOH)2] (4), [PtCl2(C7H11N2O2)2] (14), and [PtCl2(C8-
H13N2O2)2] (15). This material is available free of charge via the Internet
at http://pubs.acs.org.
IC990552M
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