Robert Melanson

[Cr(bipy)(C2O4)2]−—a versatile building block for the design of heteropolymetallic systems 2. Syntheses and crystal structures of and (AgCr(bipy)(μ-C2O4)2(H2O)2)2 and magnetic properties of the copper(II) derivative

The compounds (1) and (AgCr(bipy)(μ-C2O4)2(H2O)2)2 (2) have been obtained by self-assembling [Cr(bipy)(C2O4)2]− building blocks with Cu(II) and Ag(I) ions, respectively. The molecular and crystal structures of the two compounds were determined. Crystal 1 is monoclinic, , Z = 4 and R = 0.0369. Its structure consists of discrete linear {CrCuCr} trinuclear species with the copper atom lying on an inversion center. The copper atom exhibits [4 + 2] axially elongated octahedral geometry, the apical positions being occupied by two oxalato oxygen atoms. The CuO bond distances are 1.953(4) (H2O), 1.998(3) and 2.357(3) A, the CrO bonds vary from 1.945(3) to 1.982(3) A, and the CrN bonds are 2.031(4) and 2.054(3) A. The Cr…Cu distances are 5.288 A. Crystal 2 is monoclinic, P21/c, a = 14.639(16), b = 15.553(10), , and contains discrete tetranuclear cycles formed by two chromium and two silver atoms bridged by the oxalato groups. The silver atoms are penta-coordinated, exhibiting distorted trigonal bipyramidal geometries. The AgO bond distances vary from 2.350(8) to 2.548(7) A, while the CrO bonds are in the range 1.942(7) to 1.982(6) A. The magnetic susceptibility data of 1 reveal an irregular spin state structure with S = 5/2 ground state and an antiferromagnetic interaction between the central copper(II) and the chromium(III) atoms (J = −18.8 cm−1.

Preparation and crystal structure of bis(acetato) (trans-1,2-diaminocyclohexane) platinum(II)

Abstract The structure of the complex [Pt( trans -1,2-di- aminocyclohexane) (acetate) 2 ]·H 2 O has been determined by X-ray diffraction. This racemic compound is orthorhombic, space group Ab a2, a = 20.813(9), b = 7.926(5), c = 17.296(8) A, Z = 8. The structure was refined on 1214 nonzero Cu Kα reflections to R = 0.028. The square planar environment of Pt includes the amino groups of the diamine in cis positions and oxygens from two monodentate acetates. The PtN and PtO distances average 2.00(3) and 2.02(3) A, respectively. The bite of the diamine ligand imposes a NPtN angle of 85(1)°, whereas the small OPtO angle of 85(1)° probably results from packing effects. The average plane through the puckered cyclohexyl ring makes an angle of 19° with the PtN 2 O 2 plane. The molecules are stacked by pairs along the b axis. The two molecules of each pair are 180° apart about the stacking axis, and form altogether four NH···O hydrogen bonds.

Crystal structures of diammine(oxalato)platinum(II)and diammine(malonato)platinum(II)

Abstract [Pt(NH 3 ) 2 malonate] belongs to the monoclinic space group P 1 / c , a = 4.063(2), b = 14.150(2), c = 11.414(2) A, β = 93.27(2)°, Z = 4. The structure was refined on 1274 nonzero CuKα reflections to R = 0.035. The crystal contains individual square planar molecules with two cis NH 3 ligands at 2.036(9) A from Pt. The Pt-O distances to the bidentate malonate average 2.022(6) A and the chelate ring has a boat conformation. The angles around Pt lie in the range 86.0–93.5° (σ = 0.3°). The molecules are stacked along the a axis and form NH⋯O bonds with adjacent molecules. [Pt(NH 3 ) 2 oxalate] is monoclinic, space group P 2 1 / m , a = 3.865(2), b =10.703(4), c = 6.774(3) A, β = 94.29(4)°. Z = 2. The structure was refined on 449 non-zero MoKα reflections to R = 0.045. The square planar monomeric molecule possesses a crystallographic mirror plane perpendicular to the coordination plane and bisecting the N-Pt-N and O-Pt-O angles. The oxalate imposes an O-Pt-O angle of 82.0° in the chelate ring. The molecules are stacked in columns in the a direction, and form inter-column hydrogen bond in the b and c directions.

Study of the aqueous reactions of K[Pt(Ph2SO)Cl3] with nitrile ligands and crystal structures of N(C4H9)4[Pt(Ph2SO)Cl3], N(C2H5)4[Pt(Ph2SO)Br3] and cis-Pt(Ph2SO)(C3H5CN)Cl2

Abstract The aqeuous reactions of K[Pt(Ph2So)Cl1] with nitriles were studied in different conditions of pH, mainly by 195Pt and 1H NMR. At normal pH (≈ 2.4), the ligands RCN have produced the neutral complexes Pt(Ph2SO)(RCN)Cl2. For acetonitrile, only the cis isomer was obtained, while for other nitriles a mixture of the two isomers was formed. The 195Pt NMR spectra of the compounds were measured. The signals of the cis isomers were observed around −3040 ppm, while those of the trans isomers were found around − 3180 ppm. The study has shown that the first product formed is the trans isomer, which then isomerizes partially to the cis compounds. The 195Pt NMR spectra of the products obtained in neutral medium (pH adjusted to ∼ 7 with NaOH) have shown several signals depending on the nitrile. Dimeric species of the type Pt(Ph2SO)Cl(μ-NHC(R)O2Pt(Ph2SO)Cl are suggested to exist in solution. Head-to-head and head-to-tail isomers are probably formed. The crystal structures of N(C4H9)4[Pt(Ph2SO)Cl3] (I), N(C2H5)4[Pt(Ph2SO)Br3] (II) and cis-Pt(Ph2SO)(C3H5CN)Cl2 (III) were determined. The chloro ionic complex is triclinic, P-1, with a = 10.674(2), b = 11.424(2), c = 13.731(2) A , α = 89.54(1), β = 83.27(1), γ = 80.48(1)°, Z = 2 rmand R = 0.042, while the bromo complex is monoclinic, P21/n, with a = 11.258(3), b = 19.425(4), c = 11.590(2) A , β = 102.62(2)°, Z = 4 and R = 0.053 . Crystal III is orthorhombic, space group P2 1 2 1 2 1 , a = 9.532(3), b = 11.787(2), c = 15.464(4) A , Z = 4 and R = 0.031 . The compound is the cis isomer. For crystal I, the PtCl bond in trans position to the sulfoxide is 2.312(2) A, while the cis bonds are 2.282(2) and 2.299(2) A. For the bromo compound (II), the PtBr bonds vary between 2.397(3) and 2.421(3) A. In crystal III, the PtCl bond located in trans position to the nitrile is considerably shorter (2.269(3) A) than the PtCl bond in trans position to the sulfoxide ligand (2.311(3) A). The PtS bond distances vary between 2.201(2) and 2.228(3) A.

Molecular and crystal structures of cis-Pt(DMSO)(C2H5CN)C12 and Cl(DMSO)Pt(μ-N(CH3)CHO)2Pt(DMSO)Cl

Abstract The aqueous reaction of K[Pt(DMSO)Cl 3 ] with propionitrile at normal pH (∼2.4), gave the product Pt(DMSO)(C 2 H 5 CN)Cl 2 which was studied by X-ray diffraction methods. The crystals belongs to the monoclinic P 2 1 space group, with a =8.188(3), b =7.193(3), c =10.325(4) A, β=116.76(3)° and Z =2. The results have confirmed the cis geometry of the complex. The coordination around the Pt atom is square planar, hut there are important distortions towards a square pyramidal structure. The bond distances are: PtCl, 2.337(5), 2.328(3); PtS, 2.217(4); PtN, 1.951(6) A. The aqueous reaction of K[Pt(DMSO)Cl 3 ] with N -methylformamide at neutral pH (adjusted with NaOH) produced the N -methylformamido-bridged dimer Cl(DMSO)Pt(μ-N(CH 3 )CHO) 2 Pt(DMSO)Cl whose crystal structure was determined. The compound belongs to the monoclinic P 2 1 / c space group, with a =8.482(3), b =10.512(5), c =24.124(10) A, β=124.52(2)° and Z =4. The results have shown that the dimer is the head-to- tail isomer with the DMSO ligands located in trans position to the O -formamido atoms. The bond distances are: PtCl, 2.314(3), 2.305(4); PtS, 2.183(3), 2.198(3); PtO, 2.049(7), 2.040(9); PtN, 2.018(9), 2.019(9) A. The dihedral angle between the two Pt(II) planes is 42°.

Rearrangement of tetramethylthiourea to dimethyldithiocarbamate and crystal structures of [Tc(O)(C5H12N2S)2((CH3)2NCSS)](PF6)2 and [Tc(DPPE)2((CH3)2NCSS)](PF6)

Abstract The reaction of [Tc v (O)(tetramethylthiourea) 4 ](PF 6 ) 3 with bis(diphenylphosphino)ethane (DPPE) in DMF solution produced at least two compounds, which were identified by X-ray diffraction methods as [Tc v (O)(tetramethylthiourea) 2 ((CH 3 ) 2 NCSS)](PF 6 ) 2 and [Tc II (DPPE) 2 ((CH 3 ) 2 NCSS)](PF 6 ). The bidentate dithiocarbamate ligand was produced from the reaction of bonded tetramethylthiourea in the reaction medium. The crystals of the Tc(V) compound, [Tc(O)(tetramethylthiourea) 2 ((CH 3 ) 2 NCSS)](PF 6 ) 2 are monoclinic with P 2 1 / c space group, a =9.388(4), b =26.745(20), c =11.990(3) A, β=101.62(3)° and Z =4. The structure was refined to R =0.059 and R w =0.069. The geometry around the Tc atom is square pyramidal. The TcO bond distance is 1.661(6) A while the TcS bond lengths are 2.328(2) and 2.343(2) A for tetramethylthiourea and 2.349(2) and 2.353(2) A for dimethyldithiocarbamate. The crystals of [Tc(DPPE) 2 ((CH 3 ) 2 NCSS)](PF 6 ) are monoclinic, P 2 1 space group with a =11.693(8), b =19.282(7), c =12.148(6) A, β=104.78(5)° and Z =2. The structure was refined to R =0.074 and R w =0.063. The Tc(II) complex has a distorted octahedral geometry. The TcP bond distances vary from 2.413(6) to 2.473(6) A while the TcS distances are 2.439(6) and 2.448(7) A. The bidentate dimethyldithiocarbamate ligand is planar. A mechanism for the formation of the ligand is suggested.

Synthesis and crystal structures of oxo pyridinemethanolate technetium(V) complexes

Abstract Oxo Tc(V) complexes with 2-(hydroxymethyl)pyridine and 2,6-di(hydroxymethyl)pyridine were synthesized from the reaction of n-Bu4[Tc(O)X4] (X = Cl or Br) with the ligand in methanol or ethanol. The three compounds Tc(O)(OCH2PyCH2OH)2Cl (1). Tc(O) (OCH2PyCH2OH)2Br (2) and Tc(O) (OCH2Py)2Cl (3) (Py = pyridine) were studied by crystallographic methods. Crystal 1 is triclinic, P 1 , a = 7.479(2), b = 8.043(2), c = 14.940(4) A , α = 93.66(2), β = 102.16(2), γ = 117.18(2)°, Z = 2 and R = 0.050 . The bromo analogue 2 is also triclinic, P 1 , a = 7.416(4), b = 8.115(4), c = 15.151(10) A , α = 94.36(5), β = 102.09(5), γ = 116.77(4)°, Z = 2 and R = 0.060 . Compound 3 crystallizes in the monoclinic P21/c space group with a = 12.861(4), b = 7.111(2), c = 14.623(6) A , β = 92.86(3)°, Z = 4 and R = 0.043 . The geometry around the Tc atom is a very distorted octahedron with the oxo and halide ligands in cis position to each other. Crystal 3 is disordered on two positions. The two organic ligands are deprotonated and the disubstituted molecule 2,6-di(hydroxymethyl)pyridine in 1 and 2 is bidentate with one free -CH2OH group.

Structures of trans-[TcCl4{P(CH3)3}2] and [P(C7H7)3{C(CH3)2CH2COCH3}]2[TcCl6]

Tetrachlorobis(trimethylphosphine)techne- tium, trans-(TcC14(C3H9P)2) (I), Mr = 392.88, mono- clinic, P21/c, a= 6.639 (2), b = 8.443 (3), c= 13.559 (4) A, /3 = 100.73 (2) °, V= 746.7 (4) A 3, Z 2, Dx = 1.738 Mg m -3, ,~(Mo Ka)= 0.71069 )k, # = 1.82 mm-~, F(000) = 390, T = 295 and R = 0.036 for 932 observed reflections. The Tc atom is located on an inversion centre. The Tc--P distances are 2.524(2)A while the Tc--C1 bonds are 2.320 (1) and 2.330 (2) A. Bis((1,1-dimethyl-3-oxobutyl)tris(4- methylphenyl)phosphonium) hexachlorotechnetate, (P(C7HT)3(C6H~IO))(TcC16) (II), Mr = 1118.68, mono- clinic, P2~/c, a=15.120(4), b=11.038(3), c = 21.146 (6) A, /3 = 128.59 (2) °, V= 2759 (1) A 3, Z = 2, Dx = 1.344 Mg m -3, ,~(Mo Ka) = 0.71069/~,,/x = 0.64 mm-~, F(000) = 1158, T = 295 K and R = 0.041 for 3019 observed reflections. The Tc atom of the (TcCI6) 2- anion is located on an inversion center. The Tc--C1 bonds vary from 2.352 (2) to 2.359 (1)/~. The ((CTH7)3PC(CH3)2CH2COCH3) ÷ cation was formed from the reaction of P(p-tolyl)3 with acetone as solvent. Introduction. The chemistry of technetium has recently become very important especially in relation to the use of the isotope 99m in radiopharmacy. 99mTC is an ideal nucleus for diagnostic studies in nuclear medicine. It has been used for several years for bone scanning and recently it has been used to study the heart, brain, kidneys, liver and other organs, and also tumor tissue. A good review on medical diagnostic imaging with complexes of 99mTc has been published by Clarke & Podbielski (1987). The most recent advances in this area were published in a book edited by Nicolini, Bandoli & Mazzi (1990). We have begun a project on the synthesis of new technetium compounds, especially mixed ligand com- plexes, and have prepared several phosphine com- pounds as starting materials for these syntheses. Since small quantities of reactants are used, X-ray

Synthesis and crystal structures of nitrido diphosphinoethane technetium(V) complexes

Abstract The reaction of [Tc(N)(tu) 4 Cl]Cl with bis(dimethylphosphino)ethane(dmpe) or bis(diphenylphosphino)ethane (dppe) in ethanol solution produced yellow compounds, which were characterized by X-ray diffraction methods. The geometry around the technetium atom in [Tc(N)(dmpe) 2 Cl]CF 3 SO 3 ·0.5(NH 2 CSNH 2 ) is octahedral with the chloro ligand located in the position trans to the nitrido ligand. The Tc-N bond distance is 1.613(9) A, Tc-Cl = 2.643(3) A and the Tc-P bonds vary from 2.450(3) to 2.459(3) A. The anions are in the mirror planes and the compound crystallized with a molecule of thiourea, which is also located in the mirror. The compound with dppe crystallized with a molecule of methanol. The geometry around the technetium atom in [Tc(N)(dppe) 2 Cl]Cl·CH 3 OH is octahedral with the chloro ligand located in the position trans to the nitrido ligand. The technetium atom is located on an inversion centre and the Cl − and nitrido ligands are disordered on each side of the TcP 4 plane. The Tc-N [1.794(7) A] and Tc-Cl [2.412(2) A] bond distances are probably not precise, caused by the refinement of the disordered atoms. The Tc-P bonds are 2.491(1) and 2.473(1) A. The anions are also located on an inversion centre. The methanol molecules are disordered on two positions.

The influence of different n-substituted diethylenetriamine ligands on the aggregation of copper(II) monoacetato complexes

Abstract Complexes with different structural features were formed from the reaction of Cu 2 (MeCOO) 4 (H 2 O) 2 with various N -methyl derivatives of diethylenetriamine (dien) in the presence of ClO 4 − or PF 6 − . Four compounds were obtained and studied by crystallographic methods: [Cu(Me 5 dien)(MeCOO)(H 2 O)](ClO 4 ) ( 1 ), [Cu(1,4-Me 2 dien)(MeCOO)](ClO 4 ) ( 2 ), [Cu(1,1-Me 2 dien)(MeCOO)] n (ClO 4 ) n ( 3 ) and [Cu(1,1-Me 2 dien)(MeCOO)] n (PF 6 ) n ( 4 ). The differences between the three perchlorate compounds arise in the coordination modes exhibited by the acetato groups: monodentate terminal, asymmetric chelating and syn-anti bridging. In 1 the structure consists of discrete ions, containing terminal monodentate acetato ligands. Compounds 2 contains discrete cations interconnected through hydrogen bonds between the acetato ligand and the tridentate amine and 3 is polymeric, forming an infinite chain through acetato bridges. Compound 4 has a structure similar to 3 . The four compounds were characterized by EPR, electronic and IR spectroscopy.