Santo Lanza

Platinum(II) complexes containing dimethylsulphoxide and linear aliphatic diamines formation of a seven-membered chelate ring

Abstract The synthesis and properties of complexes of the type [Pt(diamine)(dmso)Cl]Cl containing chelate rings of increasing size are reported (dmso = dimethylsulphoxide; diamine = 1,2-diamminoethane (en), 1,3-diaminopropane (tn), and 1,4-diaminobutane (bn)). The 1,4-diaminobutane complex contains the rate seven-membered ring and is formed together with a binuclear complex, trans-[Pt(dmso)Cl2]2(NH2(CH2)4NH2), in which the amine bridges two platinum atoms. The compounds have been characterised by analysis, conductance, spectroscopic and nuclear magnetic resonance measurements. On heating the en and the tn complexes under reduced pressure dimethylsulphoxide is lost and the corresponding uncharged [Pt(diamine)Cl2] species is formed.

Homo- and heterobimetallic complexes containing 2,2′-bipyrimidine

Abstract Homo- and heterobimetallic complexes of platinum(II) containing 2,2′-bipyrimidine as bridging ligand, (C 6 H 5 ) 2 Pt(bipym)ML 2 (M = Pt, L = C 6 H 5 , M = Hg or Mn, L = Cl), were prepared by reacting the mononuclear chelate complex (C 6 H 5 ) 2 Pt(bipym) with the appropriate metal salt. The homodinuclear complexes Cl 2 M(bipym)MCl 2 (M = Hg or Mn) were synthesized from the reaction between MCl 2 and bipyrimidine. All the complexes were characterized by elemental analysis and infrared spectra, and some by proton magnetic resonance spectra. Infrared data suggest that mercury and manganese in their complexes are tetrahedrally surrounded by the donor atoms.

Platinum(II) complexes of N,N′-di-nbutyldithiooxamide showing a peculiar +NH···Cl− interaction. The crystal and molecular structure of bis-di-nbutyldithiooxamidato-platinum(II)

Abstract N,N′-di-butyldithiooxamide, nbu2-DTO, reacts in chloroform with neutral complexes of the type cis-PtL2Cl2. When L=bz2S or 1 2 COD the tight contact ion pair {Pt(H2-nbu2-DTO)22+,(Cl−)2} (1) is obtained for any metal to ligand ratio. When L is Me2SO the ion pair {(Me2SO)ClPt(H2-nbu2-DTO+,(Cl−)} (2) separates in the solid state on adding the ligand to platinum in a 1:1 ratio. This monochelate complex, however, is unstable in chloroformic solution where a symmetrization equilibrium with the corresponding bis-chelate ion pair 1 and the dichloroplatinum starting material can be found. Compound 1 by reaction with pyridine, dipyridine, phenanthroline or similar nitrogen Lewis bases loses one or both HCl molecules so giving {Pt(H-nbu2-DTO)(H2-nbu2-DTO)+,(Cl−)} (3) or [Pt(H-nbu2-DTO)2] (4), depending on the base concentration. Dissolution of 1 in a basic solvent (DMF, alcohols) leads to the formation of the neutral species 4, which is also formed when a chloroformic solution of 1 undergoes a double phase reaction with the −OH group of HOH, AlOH or SiOH. Compound 4 crystallizes in the monoclinic space group P21/c, with a=10.572(2), b=10.748(1), c=12.165(2) A, β=93.37(2)°, V=1379.9(4) A3, Z=2 and Dcalc=1.58 g cm−3; the structure was refined to R=0.033 and Rw=0.038. The [Pt(H-nbu2-DTO)2] complex has imposed square-planar geometry about the Pt atom, two thioamide S atoms of the nbu2-DTO molecule acting as a chelating ligand. The two crystallographically independent values for the PtS bond distance are: PtS(1)=2.297(3) A and PtS(2)=2.284(2) A, the bond angles are very close to 90°. The deprotonated complex [Pt(H-nbu2-DTO)2] (4) restores the ion pair by a double phase reaction with aqueous HCl, while none of the oxoacids is able to give {Pt(H2-nbu2-DTO)22+,(Ox−)2} (Ox−=oxoanion). As a consequence, the + NH···Cl− hydrogen interaction in {Pt(H2-nbu2-DTO)22+,(Cl−)2} is thought to be crucial in stabilizing the tight ion pair.

Organoplatinum(II) complexes containing disubstituted dithioxamides: Evidence for an S,S′ Pt coordinated neutral dithioxamide acting as an anion binding agent

Abstract cis -[PtL 2 R 2 ] (L = Me 2 SO or Me 2 S; R = Me or Ph) species react with N,N′-disubstituted dithioxamides H 2 -R′ 2 -DTO (R′ = methyl, benzyl, n-butyl) leading to a new class of organoplatinum compounds of general formula [PtL(R)(H-R′2-DTO)] ( 1 ). These are the first reported organometallic complexes containing an S,S′ Pt chelated rubeanate. The new compounds react with some neutral ligands L′ (L′= carbon monoxide, phosphines and thioureas) giving [PtL′(R)(H-R′ 2 -DTO)] ( 2 ) products, which are totally unreactive toward nitrogen bases such as amines, pyridines and anilines. The compound trans -[Pt(Me 2 SO) 2 MeCl] reacts with H 2 -bz 2 -DTO forming the contact ion pair {Pt(Me 2 SO)Me(H 2 -bz 2 -DTO) + ,(Cl − )} ( 3 ); this is a non-isolable species since the PtCH 3 bond is cleaved by acidic hydrogens of the coordinated neutral dithioxamide leading to the formation of methane and [Pt(Me 2 SO)Cl(H-bz 2 -DTO)] ( 4 ). A structure for the tight ion pair {Pt(Me 2 SO)Me(H 2 -bz 2 -DTO) + ,(Cl − )} is proposed in which the coordinated neutral dithioxamide acts as an anion binding agent.

Complexes of platinum(II) containing 2,2′-bithiazoline and 2,2′-bipyrimidine as binucleating ligands

Dimethyl and diphenyl platinum(II) complexes containing binucleating α-diimine ligands BN (BN = 2,2′-bithiazoline and 2,2′-bipyrimidine) have been isolated and characterized. Electrophilic attack of mercuric chloride on the mononuclear compounds leads to binuclear systems of C2v symmetry, with the two chelating moieties of the ligands occupied by platinum and mercury, respectively. 1H NMR spectroscopy suggests a large transmission of electronic effects between the metals through the ligands.

Dissociative substitution in four-co-ordinate planner platinium(II) complexes. The kinetic of sulphoxide exchange and its displacement by bidentate ligands in the reactions of cis- di(aryl)bis(dimethyl sulphoxide) platinum(II) in chloroform and benzene

A parallel flow 1H n.m.r. and u.v. spectrophotometric study of the exchange of Me2SO with (CD3)2SO, and the displacement of Me2SO by L–L [L–L = 2,2′-bipyridine, 1,10-phenanthroline, and 1,2-bis(diphenylphosphino)ethane] from cis-[Pt(Ph)2(Me2SO)2] in CDCl3 and benzene indicates that the main reaction path is dissociative with [Pt(Ph)2(Me2SO)] as the reactive intermediate.

Solid-state luminescence switching of platinum(II) dithiooxamide complexes in the presence of hydrogen halide and amine gases

In the solid state, a non-luminescent platinum(ii) dithiooxamide species adsorbs gaseous HCl, yielding a tight ion pair species which exhibits photoluminescence; the process is quantitatively reversed on heating or by exposing the sample to ammonia vapors.

Long chain secondary dithiooxamides as ligands for the synthesis of platinum(II) metallomesogens

Abstract In the search for platinum complexes of secondary dithiooxamides (RNHCS) 2 (termed as R 2 H 2 DTO), showing metallomesogenic properties, several [Pt(R 2 HDTO) 2 ] were synthesised starting from cis -[Pt(Me 2 SO) 2 Cl 2 ]. The paper is mainly devoted to the co-ordination chemistry of long chain dithiooxamides which in some cases show a different behaviour with respect to R 2 H 2 DTO bearing small substituents on nitrogen atoms. The observed reactivity appears related only in part to the lower basicity of amide nitrogen atoms in diaryl- with respect to dialkyl-dithiooxamides, and differently populated conformations of the complexes seem to play an important role. Mesophase formation for [Pt(R 2 HDTO) 2 ] with R = 3,4-[CH 3 (CH 2 ) 9 O] 2 C 6 H 3 and 3,4-[CH 3 (CH 2 ) 11 O] 2 C 6 H 3 is suggested by polarising optical microscopy and differential scanning calorimetry. The synthesis of analogous bis-chelates, but with two different dithiooxamide ligands, is also described.

A new example of stereoisomerism in inorganic chemistry: PtRu chiral axis in [(η6-p-cymene)RuCl(μ-N,N′-dialkyldithiox-amidato N,N′-Ru-S,S′Pt)Pt(2-diphenylphosphinopyridine)Cl]

Abstract The novel compounds [(η6-p-cymene)RuCl(μ-RR-DTO N,N′Ru S,S′-Pt)Pt(RR-DTO)(P-N)Cl] (P-N = 2-diphenylphosphino-pyridine, RR-DTO = N,N′-dialkyl-dithioxamidato, R = benzyl, 1; R = (R)-(−)-2-hydroxypropyl (coming from (R)-(−)-2-hydroxypropyl-amine), 2;) exhibit a PtRu chiral axis which is a new example of stereoisomerism in inorganic chemistry. The crystal structure of 2 is also reported.

Transfer of chelate ligands between platinum complexes

Abstract Me2Pt(bt) (bt = 2,2′-bithiazoline N,N′-coordinated) undergoes oxidative addition of CH2Cl2, CH2Br2 and MeI. The octahedral triorganoplatinum(IV) products react with cis-Pt(dmso)2Cl2 to give, through the transfer of the chelate ligand bt, the complex Pt(bt)Cl2 and an isomeric mixture of bis-dmso triorganoplatinum (IV) complexes.