Iodo-bridged dimers of the type I(amine)Pt(μ-I)
2Pt(amine)I were characterized by multinuclear (
195Pt,
1H and
13C) magnetic resonance spectroscopy. Two isomers are present in solution. The compounds ...are usually contaminated with Pt(amine)
2I
2. The structures were confirmed by X-ray diffraction.
Complexes of the types
cis-Pt(amine)
2I
2 were transformed into the iodo-bridged dimers, which were characterized mainly by multinuclear (
195Pt,
1H and
13C) magnetic resonance spectroscopy. For bulby amines, the dinuclear species were synthesized directly from K
2PtI
4. Compounds with several primary aliphatic and cyclic amines and two secondary amines were studied. In
195Pt NMR, two signals were observed between −3899 and −4080
ppm in acetone. These species were assigned to the
cis and
trans dinuclear compounds I(amine)Pt(μ-I)
2PtI(amine). We suggest that the most shielded compound is the
trans isomer. The difference between the two isomers is 12–13
ppm for the primary amine system and 26–27
ppm for the two secondary amines. There seems to be a slight dependence of the proton affinity in the gas phase of the amine (linear amines) with the
δ(Pt) chemical shifts of the dinuclear Pt(II) compounds. The
2
J(
195Pt–
1HN) coupling constants are slightly larger for the trans isomers (average 67
Hz, vs. 56
Hz). The
3
J(
195Pt–
1H) coupling constants were detected only for the dimethylamine compounds, 46
Hz (
trans) and 44
Hz (
cis). In
13C NMR, the values of
2
J(
195Pt–
13C) and
3
J(
195Pt–
13C) were also found to be very slightly larger for the
trans complexes (average 19 and 25
Hz vs. 15 and 18
Hz). The structures were confirmed by X-ray diffraction studies of the
n-butylamine and diethylamine compounds. The two crystals were those of the
trans dinuclear complexes.
Zn(NO
3)
2, Cd(NO
3)
2 and Cd(ClO
4)
2 form
trans-octahedral M(H
2biim)
2L
2
n+
species, where H
2biim is chelating bidentate and the apical ligands are H
2O, CH
3OH or counter-anions, whereas ...tetrahedral Zn(H
2biim)Cl
2 is obtained from ZnCl
2. The tris-chelate Cd(H
2biim)
3
2(SiF
6)(BF
4)
2
·
6EtOH is isolated from Cd(BF
4)
2 reacted in a glass vessel. Hydrogen bonding plays a determining role in crystal packing.
The reactions of zinc and cadmium salts with 2,2′-biimidazole (H
2biim) yielded a series of compounds in which the ligand is coordinated in the chelating bidentate mode. ZnCl
2 and Ag(H
2biim)(NO
3) in methanol in a 2:1 proportion produced Zn(H
2biim)Cl
2, in which the metal has a distorted tetrahedral coordination. A 1:2 ratio led to Zn(H
2biim)
2(CH
3OH)
2(NO
3)
2, containing an octahedrally coordinated Zn(II) center with the O-bonded methanol ligands occupying
trans positions. The corresponding Cd(H
2biim)
2(CH
3OH)
2(NO
3)
2 compound was obtained from CdCl
2. By starting with Cd(NO
3)
2 and Cd(ClO
4)
2 in aqueous media, the related octahedral bis-chelate compounds Cd(H
2biim)
2(NO
3)(H
2O)(NO
3) and Cd(H
2biim)
2(ClO
4)
2, respectively, were isolated, the apical positions being filled by perchlorate oxygens in the latter case. With Cd(BF
4)
2, the glass container participated in the reaction and a tris-chelate complex Cd(H
2biim)
3
2(SiF
6)(BF
4)
2
·
6EtOH was isolated. The Cd(H
2biim)
3
2+ and
SiF
6
2
-
ions define an extended hydrogen-bonded network, in which
BF
4
-
ions surrounded by disordered ethanol molecules occupy large cavities. The two free N–H groups provide H
2biim with a unique ability to form hydrogen bonds and their interactions with counter anions or other acceptors play a determining role in controlling molecular packing. The IR spectra of all compounds are discussed.
New ionic technetium complexes of the type trans-Tc(PR3)4Cl2+ are synthesized by various methods. The simplest method is the reaction of TcO4- with the phosphine in methanol in the presence of a ...chloride salt. Compounds containing PMe2Ph and PMe3 are synthesized and characterized by crystallographic methods. The complexes containing the less bulky phosphine can be prepared from complexes containing the bulkier phosphine. The compounds are paramagnetic, with two unpaired electrons. The complexes studied by X-ray diffraction methods are the trans isomers. Tc(PMe2Ph)4Cl2PF6 crystallizes in the monoclinic space group P21/c, with a = 11.511(2) Å, b = 26.713(7) Å, c = 12.688(3) Å, β = 92.79(1)°, Z = 4, and R1 = 0.0574. Tc(PMe3)4Cl2BPh4 (II) crystallizes in the orthorhombic space group Pbcn, with a = 18.213(5) Å, b = 22.950(5) Å, c = 19.428(6) Å, Z = 8, and R1 = 0.0691. Tc(PMe3)4Cl2PF6 crystallizes in the monoclinic space group P21/c, with a = 18.152(7) Å, b = 16.838(9) Å, c = 18.090(6) Å, β = 106.63(1)°, Z = 8, and R1 = 0.0670. The compounds all have octahedral coordination, but an important tetrahedral deformation of the plane containing the Tc and the four P atoms is observed in each case. In II, the two independent Tc atoms are both located on 2-fold axes.
The reaction of Mn(II), Zn(II), and Ni(II) perchlorate with 1,2-bis(4-pyridyl)ethane (bpe) was studied and the products were characterized by IR spectroscopy and X-ray diffraction methods. The zinc ...and nickel compounds are isomorphous with a metal-bpe molar ratio of 1:4, while the manganese compound is quite different with a Mn-bpe ratio of 1:5. Mn( -bpe)(H
2
O)
4
(ClO
4
)
2
·4(bpe)·2H
2
O (
1
) is monoclinic, C2/c, with a = 30.141(7), b = 13.993(4), c = 19.765(4) Å, = 129.41(1)°, and R = 0.059. The Mn atom is located on an inversion centre and forms an infinite chain with the bridged bpe ligand. The four other bpe molecules are hydrogen-bonded to the aqua ligands and form an extensive H-bonded interpenetrating 3D network. The bonds Mn-N = 2.316(3) Å and Mn-OH
2
= 2.148(4) and 2.178(3) Å. Zn( -bpe)(bpe)
2
(H
2
O)
2
(ClO
4
)
2
·bpe·H
2
O (
2
) crystallized in the P2
1
/c space group, with a = 14.609(4), b = 21.164(5), c = 16.482(5) Å, = 114.69(2)°, and R = 0.058. For Ni( -bpe)(bpe)
2
(H
2
O)
2
(ClO
4
)
2
·bpe·H
2
O (
3
), a = 14.511(6), b = 21.216(7), c = 16.467(7) Å, = 114.76(3)°, and R = 0.065. The aqua ligands are located trans to each other. The bridged bpe ligands form an infinite chain with the metal atoms. Two other terminal bpe ligands are coordinated to the metal in trans positions to each other. These ligands form H-bonds with the aqua ligands of other chains resulting in an H-bonded 3D network. The Zn-N distances vary from 2.151(3) to 2.185(4) Å while the Ni-N bonds are between 2.098(10) and 2.126(11) Å. The bonds Zn-OH
2
= 2.125(4), 2.161(4) Å and Ni-OH
2
= 2.077(11), 2.110(11) Å.
Key words: crystal structure, manganese complex, zinc complex, nickel complex, 1,2-bis(4-pyridyl)ethane.
Compounds containing aromatic amines of the types
cis- and
trans-Pt(amine)
2I
2, Pt(amine)
4I
2 and I(amine)Pt(μ-I)
2Pt(amine)I have been synthesized and characterized by IR and multinuclear (
195Pt,
...13C and
1H) NMR spectroscopies. The coupling constants
2
J(
195Pt–
1HN) are larger for the
cis isomers than for the
trans compounds. Two configurations were observed in solution for the diiodo-bridged dimers.
Pt(II) complexes of the types
cis- and
trans-Pt(amine)
2I
2 with amines containing a phenyl group were synthesized and studied mainly by IR and multinuclear (
195Pt,
1H and
13C) magnetic resonance spectroscopies. The compounds are not very soluble. In
195Pt NMR spectroscopy, the
cis isomers were observed at slightly lower fields than the
trans analogues (average Δ
δ
=
11
ppm) in acetone. In
1H NMR, the NH groups were also found at slightly lower fields in the
cis isomers. The coupling constants
2
J(
195Pt–
1HN) varied from 53 to 85
Hz and seem slightly smaller in the
trans configuration. The
13C NMR spectra of most of the complexes were measured. No coupling constants
J(
195Pt–
13C) were detected due to the low solubility of the compounds. The
cis isomers containing a phenyl group on the N atom could not be isolated except for Ph-NH
2 which was shown to be a mixture of isomers in acetone. The tetrasubstituted ionic compounds Pt(amine)
4I
2 for the less crowded ligands were also studied mainly by NMR spectroscopy in aqueous solution. The
195Pt chemical shifts vary between −2855 and −2909
ppm. The coupling constants
3
J(
195Pt–
1H) are about 40
Hz. The iodo-bridged dinuclear species I(amine)Pt(μ-I)
2Pt(amine)I were also synthesized and characterized. Two isomers are present in acetone solution for most of the compounds. Their
δ(Pt) signals were observed at about −4000
ppm and their coupling constants
2
J(
195Pt–
1HN) are around 69
Hz.
Baker's yeast (Saccharomyces cerevisiae) reductions were applied to the synthesis of the paclitaxel C-13 side-chain analogue. An easily synthesized alpha-keto-beta-lactam ...(1-(4-methoxyphenyl)-4-tert-butylazetidin-2,3-dione, 4) was reduced by yeast cells to give a mixture of enantiomerically pure cis and trans isomers.
Compounds of the type
cis- and
trans-Pt(Ypy)
2(NO
3)
2 (Ypy=pyridine or its methyl derivatives) have been synthesized and characterized by IR and multinuclear (
195Pt,
13C and
1H) NMR spectroscopies. ...The
195Pt NMR resonances of the
trans complexes were observed at lower fields (ave. −1450 ppm) than the
cis analogs (ave. −1509 ppm). The complexes containing a methyl substituent in
ortho position on the pyridine ligand were observed at lower fields than the others. The coupling constants
3
J(
195Pt–
1H) and
3
J(
195Pt–
13C) are larger in the
cis configuration (ave. 44 and 46 Hz, respectively) than in the
trans analogs (ave. 33 and 35 Hz, respectively). The covalent character of the PtO bond seems greater in the
trans complexes than in the
cis compounds. The crystal structures of
cis-Pt(3,5-lut)
2(NO
3)
2,
cis-Pt(2-pic)
2(NO
3)
2,
cis-Pt(py)
2(NO
3)
2·1/2CH
2Cl
2,
trans-Pt(3,5-lut)
2(NO
3)
2 and
trans-Pt(py)
2(NO
3)
2 were determined. Except for the
cis pyridine complex, which contains some molecules of solvent, the two nitrato groups are on opposite sides of the coordination plane. The
trans influence of the different ligands is compared.
Compounds of the types
cis- and
trans-Pt(Ypy)
2(NO
3)
2 where Ypy=methyl derivative of pyridine have been studied by IR and by
1H,
13C and
195Pt NMR spectroscopies. The
195Pt NMR resonances of the
trans complexes were observed at lower fields than the
cis analogs. The complexes containing a methyl substituent in
ortho position on the pyridine ligand were observed at lower fields than the others. The coupling constants
3
J(
195Pt–
1H) and
3
J(
195Pt–
13C) are larger in the
cis configuration than in the
trans analogs. The crystal structures of
cis-Pt(3,5-lut)
2(NO3)
2,
cis-Pt(2-pic)
2(NO
3)2,
cis-Pt(py)
2(NO3)
2·1/2CH
2Cl
2,
trans-Pt(3,5-lut)
2(NO
3)
2 and
trans-Pt(py)
2(NO
3)
2 were determined.
Compounds of the types
cis- and
trans-Pt(amine)
2(NO
3)
2 and Pt(amine)
2(R(COO)
2) with amines containing a phenyl group have been synthesized and characterized by IR spectroscopy. The dinitrato ...complexes were studied by
195Pt and
1H NMR spectroscopy. The coupling constants
J(
195Pt–
1H) are larger for the
cis isomers than for the
trans compounds. In
195Pt NMR, the
trans compounds were observed at lower fields than the
cis isomers, while in
1H NMR, the reverse was observed for the NH groups.
Complexes of the types
cis- and
trans-Pt(amine)
2(NO
3)
2 with amines containing a phenyl group were synthesized and studied mainly by IR and multinuclear magnetic resonance spectroscopies. The
cis complexes could be synthesized pure only with the amines of the type Ph–R–NH
2 (R
=
alkyl), while pure
trans compounds were synthesized with all the studied amines. In
195Pt NMR spectroscopy, the dinitrato complexes of the amines Ph–R–NH
2 were observed around −1700
ppm for the
cis isomers and at about −1580 for the
trans complexes. For the other amines, where a phenyl ring is directly attached to the amino group, the signals were observed at lower fields, −1528
ppm for
cis-Pt(PhNH
2)(NO
3)
2 and around −1450
ppm for all the
trans isomers. There is a linear relationship between the
δ(Pt) of the Pt(amine)
2(NO
3)
2 complexes and the p
K
a of the protonated amines. The coupling constants
2
J(
195Pt–
1HN) are larger in the
cis compounds (ave. 76
Hz) than in the
trans isomers (ave. 63
Hz). The complexes
cis-Pt(amine)
2(R(COO)
2) with bidentate dicarboxylato ligands were also synthesized and characterized mainly by IR spectroscopy. The compounds apparently decompose in DMF and are too insoluble in other solvents for solution studies.
