A bromine analogue of picoplatin: a new substance from the group of platinum-based chemotherapeutics

A new substance, cis-amminedibromido(2-methyl­pyridine-κN)platinum(II), cis-[PtBr₂(C₆H₇N)(NH₃)], which is a potential platinum-based anti­neoplastic agent for the treatment of patients with solid tumors, has been synthesized and structurally characterized. There is one mol­ecule in the asymmetric unit and mol­ecules are linked via two symmetry-independent N—H...Br hydrogen bonds into zigzag chains running parallel to the c axis. C—H...Br hydrogen bonds crosslink these chains to give a layer parallel to (010). N—H...Br hydrogen bonds and π–π stacking inter­actions between pairs of pyridine rings stack the layers along b.

Computing details

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: JANA2006 (Petříček et al., 2006); molecular graphics: ORTEP-3 (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: JANA2006 (Petříček et al., 2006).

cis-amminedibromido(2-methylpyridine-κN)platinum(II)

Crystal data

[PtBr2(C6H7N)(NH3)]	F(000) = 832
Mr = 465	Dx = 3.018 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.5418 Å
Hall symbol: -P 2ybc	Cell parameters from 13149 reflections
a = 10.0371 (3) Å	θ = 4.5–77.0°
b = 9.0733 (3) Å	µ = 34.36 mm^−1
c = 11.4901 (4) Å	T = 190 K
β = 102.120 (3)°	Block, yellow
V = 1023.07 (6) Å^3	0.23 × 0.17 × 0.10 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur diffractometer with an Onyx detector	2148 independent reflections
Radiation source: Enhance (Cu) X-ray Source	1822 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.090
Detector resolution: 8.1917 pixels mm^-1	θmax = 77.3°, θmin = 4.5°
ω scans	h = −12→12
Absorption correction: multi-scan [CrysAlis PRO (Agilent, 2011) using spherical harminics]	k = −11→11
Tmin = 0.212, Tmax = 1	l = −14→14
25523 measured reflections

Refinement

Refinement on F	40 constraints
R[F > 3σ(F)] = 0.030	H-atom parameters constrained
wR(F) = 0.036	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
S = 1.69	(Δ/σ)max = 0.013
2148 reflections	Δρmax = 1.35 e Å^−3
100 parameters	Δρmin = −2.43 e Å^−3
0 restraints

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

	x	y	z	Uiso*/Ueq
Pt1	0.37243 (3)	0.67977 (3)	0.19269 (2)	0.01751 (9)
Br1	0.25429 (7)	0.54401 (9)	0.32423 (7)	0.0241 (2)
Br2	0.58974 (7)	0.67033 (10)	0.33290 (7)	0.0292 (2)
N1	0.1947 (6)	0.6881 (6)	0.0673 (5)	0.0197 (17)
N2	0.4656 (7)	0.8066 (7)	0.0871 (6)	0.031 (2)
C2	−0.0253 (8)	0.7924 (10)	0.0069 (8)	0.037 (3)
C4	0.0498 (7)	0.6082 (9)	−0.1112 (7)	0.026 (2)
C6	0.2841 (8)	0.5045 (9)	−0.0506 (7)	0.033 (3)
C3	−0.0517 (8)	0.7047 (9)	−0.0912 (8)	0.037 (3)
C5	0.1741 (7)	0.6022 (8)	−0.0307 (6)	0.022 (2)
C1	0.0980 (8)	0.7816 (9)	0.0853 (7)	0.033 (3)
H1c2	−0.09248	0.861425	0.02128	0.0444*
H1c4	0.033681	0.546279	−0.180466	0.0312*
H1c6	0.246621	0.428601	−0.106109	0.0395*
H3c6	0.349494	0.560623	−0.082071	0.0395*
H2c6	0.327947	0.460325	0.023537	0.0395*
H1c3	−0.138423	0.708938	−0.145711	0.0443*
H1c1	0.115307	0.842899	0.154975	0.0396*
H1n2	0.496737	0.750471	0.037425	0.0377*
H3n2	0.407211	0.868809	0.047642	0.0377*
H2n2	0.532822	0.854564	0.131117	0.0377*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pt1	0.01468 (14)	0.02128 (15)	0.01572 (16)	−0.00189 (12)	0.00125 (10)	−0.00082 (12)
Br1	0.0180 (3)	0.0318 (4)	0.0222 (4)	−0.0043 (3)	0.0033 (3)	0.0025 (3)
Br2	0.0171 (3)	0.0461 (5)	0.0218 (4)	−0.0092 (3)	−0.0018 (3)	0.0026 (4)
N1	0.023 (3)	0.018 (3)	0.018 (3)	0.003 (2)	0.003 (2)	0.002 (2)
N2	0.031 (3)	0.035 (4)	0.028 (4)	−0.008 (3)	0.005 (3)	0.007 (3)
C2	0.020 (4)	0.041 (5)	0.049 (5)	0.013 (4)	0.006 (4)	0.002 (4)
C4	0.017 (3)	0.036 (4)	0.024 (4)	−0.007 (3)	0.003 (3)	0.004 (3)
C6	0.032 (4)	0.032 (4)	0.034 (5)	0.008 (4)	0.005 (4)	−0.008 (4)
C3	0.020 (4)	0.041 (5)	0.046 (5)	−0.002 (3)	0.000 (4)	0.010 (4)
C5	0.023 (3)	0.025 (4)	0.018 (3)	−0.002 (3)	0.004 (3)	−0.003 (3)
C1	0.032 (4)	0.035 (4)	0.031 (4)	0.013 (4)	0.005 (3)	−0.003 (4)

Geometric parameters (Å, º)

Pt1—Br1	2.4414 (9)	N2—H2n2	0.87
Pt1—Br2	2.4258 (7)	C2—C3	1.360 (13)
Pt1—N1	2.045 (5)	C2—C1	1.373 (11)
Pt1—N2	2.037 (7)	C2—H1c2	0.96
Br1—N1	3.169 (6)	C4—C3	1.399 (12)
Br1—N2^i	3.518 (7)	C4—C5	1.389 (9)
Br1—N2^ii	3.574 (6)	C4—H1c4	0.96
Br2—N2	3.095 (6)	C6—C5	1.471 (12)
Br2—N2^i	3.502 (7)	C6—H1c6	0.96
Br2—N2^ii	3.414 (7)	C6—H3c6	0.96
N1—C5	1.349 (9)	C6—H2c6	0.96
N1—C1	1.338 (11)	C3—H1c3	0.96
N2—H1n2	0.87	C1—H1c1	0.96
N2—H3n2	0.87
Br1—Pt1—Br2	93.26 (3)	Br1^iv—N2—Br2^iv	60.79 (11)
Br1—Pt1—N1	89.42 (18)	Br1^iv—N2—H1n2	84.17
Br1—Pt1—N2	175.9 (2)	Br1^iv—N2—H3n2	25.53
Br2—Pt1—N1	176.94 (18)	Br1^iv—N2—H2n2	123.47
Br2—Pt1—N2	87.37 (18)	Br2—N2—Br2^iii	101.10 (18)
N1—Pt1—N2	90.1 (2)	Br2—N2—Br2^iv	131.0 (2)
Pt1—Br1—N1	40.20 (11)	Br2—N2—H1n2	103.53
Pt1—Br1—N2^i	91.48 (12)	Br2—N2—H3n2	146.4
Pt1—Br1—N2^ii	93.01 (12)	Br2—N2—H2n2	63.59
N1—Br1—N2^i	120.35 (16)	Br2^iii—N2—Br2^iv	105.86 (18)
N1—Br1—N2^ii	126.39 (15)	Br2^iii—N2—H1n2	145.3
N2^i—Br1—N2^ii	72.01 (15)	Br2^iii—N2—H3n2	52.99
Pt1—Br2—N2	41.10 (13)	Br2^iii—N2—H2n2	61.44
Pt1—Br2—N2^i	92.15 (11)	Br2^iv—N2—H1n2	39.57
Pt1—Br2—N2^ii	97.31 (11)	Br2^iv—N2—H3n2	80.88
N2—Br2—N2^i	124.08 (16)	Br2^iv—N2—H2n2	95.12
N2—Br2—N2^ii	127.37 (18)	H1n2—N2—H3n2	109.47
N2^i—Br2—N2^ii	74.14 (16)	H1n2—N2—H2n2	109.47
Pt1—N1—Br1	50.38 (12)	H3n2—N2—H2n2	109.47
Pt1—N1—C5	121.7 (5)	C3—C2—C1	119.7 (8)
Pt1—N1—C1	117.9 (5)	C3—C2—H1c2	120.17
Br1—N1—C5	120.3 (4)	C1—C2—H1c2	120.17
Br1—N1—C1	96.8 (5)	C3—C4—C5	119.9 (7)
C5—N1—C1	120.4 (6)	C3—C4—H1c4	120.04
Pt1—N2—Br1^iii	127.8 (3)	C5—C4—H1c4	120.03
Pt1—N2—Br1^iv	116.9 (3)	C5—C6—H1c6	109.47
Pt1—N2—Br2	51.53 (14)	C5—C6—H3c6	109.47
Pt1—N2—Br2^iii	104.9 (3)	C5—C6—H2c6	109.47
Pt1—N2—Br2^iv	147.2 (3)	H1c6—C6—H3c6	109.47
Pt1—N2—H1n2	109.47	H1c6—C6—H2c6	109.47
Pt1—N2—H3n2	109.47	H3c6—C6—H2c6	109.47
Pt1—N2—H2n2	109.47	C2—C3—C4	118.7 (7)
Br1^iii—N2—Br1^iv	107.99 (18)	C2—C3—H1c3	120.66
Br1^iii—N2—Br2	80.58 (14)	C4—C3—H1c3	120.66
Br1^iii—N2—Br2^iii	60.53 (11)	N1—C5—C4	119.5 (7)
Br1^iii—N2—Br2^iv	78.31 (16)	N1—C5—C6	119.3 (6)
Br1^iii—N2—H1n2	99.98	C4—C5—C6	121.3 (7)
Br1^iii—N2—H3n2	99.42	N1—C1—C2	121.8 (8)
Br1^iii—N2—H2n2	18.3	N1—C1—H1c1	119.1
Br1^iv—N2—Br2	167.6 (3)	C2—C1—H1c1	119.1
Br1^iv—N2—Br2^iii	76.44 (13)

Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) x, −y+3/2, z+1/2; (iii) −x+1, y+1/2, −z+1/2; (iv) x, −y+3/2, z−1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H1N2···Br2^iv	0.87	2.80	3.414 (7)	129
N2—H3N2···Br1^iv	0.87	2.81	3.574 (6)	147
C3—H1C3···Br2^v	0.96	2.90	3.698 (8)	141
N2—H3N2···Br2^iii	0.87	3.06	3.502 (7)	114
N2—H2N2···Br1^iii	0.87	2.71	3.518 (7)	156

Symmetry codes: (iii) −x+1, y+1/2, −z+1/2; (iv) x, −y+3/2, z−1/2; (v) x−1, −y+3/2, z−1/2.