Powder study of trans-tetra­chloridobis­(isopropyl­amine)platinum(IV)

The title compound, trans-[PtCl₄(iso-NH₂C₃H₇)₂], was obtained by oxidation of trans-[PtCl₂(iso-NH₂C₃H₇)₂] with chlorine gas. The crystal structure contains discrete centrosymmetric mononuclear complex mol­ecules, with Pt^IV in a slightly distorted octa­hedral coordination environment. The slight distortion, as described by the angles at the Pt^IV atom, is due, in part, to intra­molecular N—H...Cl hydrogen bonding [N...Cl = 2.897 (12) Å]. The Pt—N and Pt—Cl bond lengths are comparable to those in related structures. In the crystal structure, mol­ecules are arranged in layers in the bc plane, with a shortest Pt...Pt distance of 6.1105 (1) Å. The mol­ecules are organized so that isopropyl­amine ligands project from the layers, forming organic inter­layers.

Key indicators

• Powder X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.012 Å
• R factor = 0.000
• wR factor = 0.000
• Data-to-parameter ratio = 0.0

checkCIF/PLATON results

No syntax errors found



Alert level B
THETM01_ALERT_3_B  The value of sine(theta_max)/wavelength is less than 0.475
            Calculated sin(theta_max)/wavelength =    0.4586

Author Response: ... This is the consequence of the X-ray powder diffraction method application. In the case of trans-Pt(2-NH2C3H7)2Cl4 : 1. there are no any useful information (significant peaks) in the powder pattern higher 90 2theta degree. 2. The combination of two factors the density of peaks and peak width in the region higher of 75 2theta make impossible an extraction useful informatiom from experimental data.

Alert level C
REFI023_ALERT_1_C  _refine_diff_density_max is missing
            Maximum value of final difference map (e A-3).
            The following tests will not be performed
            DIFMN_01,DIFMX_01,DIFMX_02
REFI024_ALERT_1_C  _refine_diff_density_min is missing
            Minimum value of final difference map (e A-3).
            The following tests will not be performed
            DIFMN_01,DIFMN_02,DIFMN_03
SHFSU01_ALERT_2_C  The absolute value of parameter shift to su ratio > 0.05
            Absolute value of the parameter shift to su ratio given   0.100
            Additional refinement cycles may be required.
PLAT080_ALERT_2_C Maximum Shift/Error ............................       0.10
PLAT164_ALERT_4_C Nr. of Refined C-H H-Atoms in Heavy-At Struct...          7
PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         12

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Pt          (2)       2.94

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   6 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Asymmetric diamine dichloro platimun(II) complexes, e.g. cis-bis(isopropylamine) dichloro platimun(II) and related compounds (Bradner et al., 1980; Hydes, 1981) can exhibit high anticancer activity. The synthesis of cis-(isopropylamine)amine dichloro platinum(II) has been described by Hydes (1981), Zhelegovskay & Fat'kin (1986) and Zhelegovskay et al. (1991). This is based on the reaction of tetrachloroplatinate(II) potassium with isopropylamine followed by refinement of the target product. The main synthetic difficulties stem from the requirements of low level of impurities because of the medical application. It justifies the interest in possible subsidiary reactions and by-products at the synthesis stage of target compounds. In the present paper, results of a synthesis and a crystal structure determination of trans-bis(isopropylamine) tetrachloro platimun(IV), performed using X-ray powder diffraction technique, are presented.

The crystal structure of trans-bis(isopropylamine) tetrachloro platimun(IV) is of the molecular type with two symmetrically equivalent molecules in unit cell. The molecular structure of the title compound presented in Fig. 2. The Pt atom lies on a center of inversion in a slightly distorted octahedral coordination environment consisting of two N and four Cl atoms. The Pt—N and Pt—Cl distances compare well to literature values (Wells, 1984, Allen, 2002). Isopropylamine as ligand induces more distortion at atom Pt in comparison to an amine as a ligand (Milburn & Truter, 1966). The N—Pt—Cl1 and N—Pt—Cl2 angles are 97.7 (3) and 86.2 (3)° respectively. The N—Cl1 distance of ca 2.89Å allows us to suppose that the distortion in the molecule is induced, in part, by intramolecular hydrogen bonds of the N—H···Cl1 type. In addition, isopropylamine ligands are connected to other molecules by intermolecular hydrogen bonds (see Table 2) and Van der Waals forces also contribute to the crystal packing. The molecules arrange in layers stretched along (bc)-plane with the shortest distances Pd···Pd within a layer about 6.1105 (2)° A. The Pt···Pt distance between layers is substantially longer ca 8.88° A. The molecules orientate in the layers, so that the bulky isopropylamine ligands project above and below each layer comprising organic interlayers (Fig. 3).

Related literature

For related literature, see: Bradner et al. (1980); Hydes (1981); Milburn & Truter (1966); Wells (1984); Zhelegovskay & Fat'kin (1986); Zhelegovskay et al. (1991). One of the figures is missing from the supplementary materials; the figure that we have labelled as figure 1 is actually figure 2 according to the CIF (the ellipsoid plot). The real figure 1 (Rietveld refinement profiles) is missing.

For related literature, see: Allen (2002); Le Bail et al. (1988); Rietveld (1969); Visser (1969).

For related literature, see: Le Bail, Duroy & Fourquet (1988).

S2. Experimental

Trans-Pt(iso-NH₂C₃H₇)₂Cl₂ (2 g) was suspended in 40 ml of water and gaseous chorine was passed through the suspension for 2 h. The yellow substance obtained was filtered, washed with ethanol and dried in air at room temperature.

S3. Refinement

The structure determination was carried out by X-ray powder diffraction approach. The experimental data were collected using DRON-4 automatic diffractometer, equipped with a secondary flat graphite monochromator in conjunction with a scintillation detector. Cu Kα radiation was used (λ₁=1.54056 Å, λ₂=1.54439 Å). The sample was prepared by top-loading the standard quartz sample holder with cutting the excess of well grained substance. The diffraction pattern was scanned with the step of 0.02° 2θ and counting time of 5 sec./step in the most informative angular range from 8° to 90% 2θ at ambient temperature. Corundum was used as the external standard. The powder pattern of cis-(isopropylamine) aminne dichloro platimun(II) is presented in Fig.1. X-ray powder diffraction data were deposited in JCPDS-ICDD PDF2 database. Cell parameters were obtained from d-spaces by indexing and refining using programs described in (Visser, 1969, Kirik et al., 1979). The space group was determined from the analysis of systematic absences. The structural investigations were carried out using a full-profile structure analysis package based on a modified version of the Rietveld refinement program DBWS– 9006PC (Wiles & Young, 1981). The intensities of 50 reflections were estimated from the powder pattern by means of the full- profile fitting procedure (Le Bail et al., 1988) and used in the Patterson synthesis. Atoms of Pt and Cl were located directly from the Patterson map. Positions of light atoms N and C were defined from a difference Fourier synthesis. H-atoms were not located, but they were included in the refined structure models and rigidly connected to their C and N atoms. The final refinement was carried out by Rietveld method (Rietveld, 1969).

Computing details

Data collection: DRON-4 (refernce?); cell refinement: POWDER (Kirik et al., 1979); program(s) used to solve structure: Modified DBWM (Wiles & Young, 1981); program(s) used to refine structure: Modified DBWM; molecular graphics: XP (Siemens, 1989) and PLATON (Spek, 2003).

Figures

	Fig. 1. Observed (dots), calculated (superimposed solid) and difference profiles after the Rietveld refinement. The reflection positions are marked by ticks.
	Fig. 2. Molecular structure of the title compound showing 30% isotropic dispacement ellipsoids.
	Fig. 3. Part of the crystal structure of trans-Pt(iso-NH2C3H7)2Cl4.

trans-tetrachloridobis(isopropylamine)platinum(IV)

Crystal data

[PtCl4(C3H9N)2]	F(000) = 428.0
Mr = 455.11	Cell parameters are obtained from the Rietveld refinement
Monoclinic, P21/c	Dx = 2.288 Mg m^−3
Hall symbol: -P 2ybc	Cu Kα radiation
a = 8.8886 (1) Å	T = 293 K
b = 8.9464 (2) Å	Particle morphology: thin powder
c = 8.3255 (2) Å	yellow
β = 93.868 (1)°	circular flate plate, 20.0 × 20.0 mm
V = 660.54 (2) Å^3	Specimen preparation: Prepared at 293 K and 101 kPa, cooled at 0 K min^−1
Z = 2

Data collection

DRON-4 powder diffractometer	Specimen mounting: packed powder pellet
Radiation source: conventional sealed tube	Data collection mode: reflection
Graphite monochromator	2θmin = 8.0°, 2θmax = 90.0°, 2θstep = 0.02°

Refinement

Refinement on F^2	Profile function: Pearson VII
Least-squares matrix: full	42 parameters
Rp = 0.078	0 restraints
Rwp = 0.107	0 constraints
Rexp = 0.073	H atoms treated by a mixture of independent and constrained refinement
RBragg = 0.040	Weighting scheme based on measured s.u.'s
R(F^2) = 0.036	(Δ/σ)max = 0.1
Excluded region(s): none	Preferred orientation correction: March-Dollase correction

Special details

Refinement. R_prof-backgr = 0.078

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Pt	0.0000	0.0000	0.0000	0.0121*
Cl1	0.2013 (5)	0.0270 (12)	0.1921 (6)	0.0151*
Cl2	0.0140 (12)	−0.2571 (6)	0.0170 (12)	0.0153*
C1	0.2950 (10)	−0.0360 (10)	−0.1890 (10)	0.0256*
H1A	0.3287 (10)	−0.1102 (10)	−0.1115 (10)	0.1520*
C2	0.3450 (10)	−0.0720 (10)	−0.3560 (10)	0.0393*
H2A	0.3072 (10)	−0.1685 (10)	−0.3890 (10)	0.1520*
H2B	0.3062 (10)	0.0023 (10)	−0.4310 (10)	0.1520*
H2C	0.4531 (10)	−0.0725 (10)	−0.3533 (10)	0.1520*
C3	0.3600 (9)	0.1200 (9)	−0.1450 (9)	0.0316*
H3A	0.4681 (9)	0.1152 (9)	−0.1367 (9)	0.152*
H3B	0.3274 (9)	0.1904 (9)	−0.2271 (9)	0.152*
H3C	0.3249 (9)	0.1513 (9)	−0.0438 (9)	0.152*
N	0.1240 (10)	−0.0200 (10)	−0.2000 (10)	0.0251*
H4A	0.1007 (10)	0.0660 (10)	−0.2660 (10)	0.1520*
H4B	0.0845 (10)	−0.1050 (10)	−0.2591 (10)	0.1520*

Geometric parameters (Å, º)

Pt—N	2.066 (9)	N—H4B	0.96 (1)
Pt—Cl1	2.331 (5)	C3—H3A	0.96 (1)
Pt—Cl2	2.307 (5)	C3—H3B	0.96 (1)
C1—C3	1.545 (12)	C3—H3C	0.96 (1)
C1—C2	1.522 (12)	C2—H2A	0.96 (1)
C1—N	1.523 (13)	C2—H2B	0.96 (1)
Pt—Pt^i	6.1105 (1)	C2—H2C	0.96 (1)
N—H4A	0.96 (1)	C1—H1A	0.96 (1)
Cl1—Pt—Cl2	91.5 (4)	Pt—N—H4B	106.3 (6)
Cl1—Pt—N	97.7 (3)	N—C1—H1A	111.8 (8)
Cl2—Pt—N	86.2 (3)	C1—C2—H2A	109.5 (8)
C2—C1—C3	106.3 (6)	C1—C2—H2B	109.5 (8)
Pt—N—C1	123.0 (6)	C1—C2—H2C	109.5 (8)
N—C1—C2	108.5 (7)	C1—C3—H3A	109.5 (7)
N—C1—C3	106.6 (7)	C1—C3—H3B	109.5 (7)
Pt—N—H4A	106.3 (6)	C1—C3—H3C	109.5 (7)

Symmetry code: (i) −x, y+1/2, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N—H4A···Cl2^ii	0.960 (12)	2.761 (12)	3.683 (12)	161.3 (9)
N—H4B···Cl2^iii	0.959 (12)	2.287 (12)	3.190 (12)	156.4 (9)

Symmetry codes: (ii) −x, y+1/2, −z−1/2; (iii) x, −y−1/2, z−1/2.