The first synthesis and X-ray structures of polyfluorinated 1,2-, 2,3- and 2,4a-dihydro-1,3-diazafluorenes

Acetic acid-catalyzed condensation of 2-amino-3-(1-imino-2,2,2-trifluoroethyl)-1,1,4,5,6,7-hexafluoroindene (1b) with acetone and cyclopentanone gives 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-2,3-dihydro-1,3-diazafluorene (2a) and 5,6,7,8,9,9-hexafluoro-4-trifluoromethyl-2,3-dihydro-1,3-diazafluorene-2-spiro-1′-cyclopentane (3a) together with small amounts of 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-1,2-dihydro-1,3-diazafluorene (2b) and 5,6,7,8,9,9-hexafluoro-4-trifluoromethyl-1,2-dihydro-1,3-diazafluorene-2-spiro-1′-cyclopentane (3b), respectively. When acted upon by (CH₃)₂SO₄ compounds 2, 3 were converted into corresponding fluorine-containing 1-methyl-1,2-dihydro-1,3-diazafluorenes 6, 7. 4a-Chloro-5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-2,4a-dihydro-1,3-diazafluorene (8) has been synthesized by the interaction of compound 2 with SOCl₂. Solution of compound 2 as well as 8 in CF₃SO₃H-CD₂Cl₂ generated 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-1,2,3,4-tetrahydro-1,3-diazafluorene-4-yl cation (2c). The structures of compounds 2, 3, 6-8 have been determined by single crystal X-ray diffraction.     

Synthesis, crystal structures, electrochemical studies and anti-tumor activities of three polynuclear organotin(IV) carboxylates containing ferrocenyl moiety

A novel ferrocene-containing ligand 3-trifluoromethyl-5-ferrocenyl -pyrazol-1-yl-acetic acid (LCOOH) and three organotin(IV) carboxylate derivatives [Ph₄Sn₂O(OCH₃)(OOCL)]₂(1), [BuSnO(OOCL)]₆(2) and [Bu₄Sn₂O(OOCL₂)₂] (3) have been synthesized and structurally characterized by means of FT-IR, elemental analysis, ¹H NMR, ¹¹⁹Sn NMR, X-ray crystallography and cyclic voltammetry. Both complexes 1 and 3 are centrosymmetric with ladder framework. Complex 2 is a hexanuclear one with drum structure. Furthermore, their anti-tumor activities were also evaluated, using HepG2 human hepatocellular liver carcinoma cells, A549 human lung carcinoma cells and B16-F10 melanoma cells. Complex 1 displayed the best cytotoxicity and can be pointed out as a promising substrate to be subject of further investigations.     

A convenient one-pot synthesis of 2-(trifluoromethyl)-3,4,7,8-tetrahydro-2H-chromen-5(6H)-one derivatives and their further transformations

The trifluoromethyl containing heterocycles, 2-hydroxy-4-aryl-3-(thien-2-oyl)-2-(trifluoromethyl)-3,4,7,8-tetrahydro-2H-chromen-5(6H)-one derivatives 4, were synthesized via a one-pot three-component reaction of aldehyde 1 with 1,3-cyclohexanedione 2 and 4,4,4-trifluoro-1-(thien-2-yl)butane-1,3-dione 3 in the presence of a catalytic amount of Et₃N. The effect of bases and solvents on the reaction efficiency and yield was briefly investigated. Treatment of 4 with an excess amount of NH₄OAc in ethanol afforded 2-trifluoromethyl-1H-quinolin-5-one derivatives 5. Refluxing of 4 with TsOH in CHCl₃ gave the corresponding dehydrated products 8.     

Study on the reactions of ethyl 4,4,4-trifluoro-3-oxobutanoate with arylidenemalononitriles

In the presence of a catalytic amount of NEt₃, ethyl 4,4,4-trifluoro-3-oxobutanoate 1 reacted readily with arylidenemalononitriles 2 in ethanol at room temperature. It gave two products 2-trifluoromethyl-3,4-dihydro-2H-pyran derivatives 3 and 2-(trifluoromethyl)piperidine derivatives 4, the ratio of 3 and 4 was depended on the substrates 2 and reaction solvents. Reflux of the ethanol solution of 4 with a catalytic amount of NEt₃ afforded 2-trifluoromethyl-1,4,5,6-tetrahydropyridine derivatives 5 in moderate to good yields. The structures of new compounds 3, 4 and 5 were determined by spectral methods, microanalysis and X-ray diffraction analysis. A possible reaction mechanism for the formation of 3, 4 and 5 was presented.     

Lewis acid-promoted reactions of ethenetricarboxylates with γ-CF3-substituted propargyl alcohols

The Lewis acid-promoted reaction of an ethenetricarboxylate derivative (1) with CF₃-substituted propargyl alcohols has been examined. Reaction of γ-CF₃ propargyl alcohols in the presence of zinc bromide gave five-membered CF₃-containing tetrahydrofurans in 66-85% yield. The CF₃ group activates alkyne as an electron-withdrawing group. On the other hand, reaction of γ-trifluoromethyl-α-aryl propargyl alcohols 2 with 1 in the presence of 1 equiv of SnCl₄ gave cyclobutane derivatives 6 in 29-49% yield. Formation of cyclobutane 6a arises from the [2+2] cycloaddition between ethenetricarboxylate 1 and chloroallene 8, which is produced by the reaction of propargyl alcohol 2a and SnCl₄.     

Perfluoro-4-methyl-1,3-dioxole: a new monomer for high-Tg amorphous fluoropolymers

A 4-Chloro-5-trifluoromethyl-2,2,4-trifluoro-1,3-dioxolane (1) was synthesised by reaction of CF₂(OF)₂ with CF₃CHCFCl; the elimination of HCl from (1) in basic conditions led to the formation of dioxole perfluoro-4-methyl-1,3-dioxole (2). Both these synthetic steps gave the corresponding product in high yield.A new synthetic route for the preparation of CF₃CHCFCl, starting from CF₂ClBr and CH₂CF₂, together with some examples of polymerisation products obtained by reaction of dioxole (2) with fluoroolefins are also reported.     

Synthesis and structures of crystalline lithium 1-azaallyls and a 1,3-diazaallyl derived from Li{CH(SiMe3)(SiMe3−n(OMe)n)} (n=1 or 2) and Li{CH(SiMe2OMe)2} and RCN (R=Bu, Ph, 2,5-Me2C6H3, or Ad)

Crystalline [Li{N(SiMe₂OMe)C(^tBu)C(H)(SiMe₃)}]₂ (5), [Li{N(SiMe₂OMe)C(Ph)C(H)(SiMe₃)}]₂ (6), [C(C₆H₃Me₂-2,5)C(H)(SiMe₃)}(TMEDA)](7), [Li{N(SiMe(OMe)₂)C(^tBu)C(H)(SiMe₃)}(THF)]₂ (8), Li{N(SiMe(OMe)₂)C(Ph)C(H)(SiMe₃)}(TMEDA) (9) and [Li{N(SiMe₂OMe)C(^tBu)C(H)(SiMe₂OMe)}]₂ (10) were readily obtained at ambient temperature from (i) [Li{CH(SiMe₃)(SiMe₂OMe)}]₈ (1) and an equivalent portion of RCN (R=^tBu (5), Ph (6) or 2,5-Me₂C₆H₃ (7)); (ii) [Li{CH(SiMe₃)(SiMe(OMe)₂)}]_∞ (2) and an equivalent portion of ^tBuCN (8) or PhCN (9); and (iii) [Li{CH(SiMe₂OMe)₂}]_∞ (3) and one equivalent of ^tBuCN (10). Reactions (i) and (ii) were regiospecific with SiMe_3−n(OMe)_n>SiMe₃ in 1,3-migration from C (in 1 or 2)→N. The 1-azaallyl ligand was bound to the lithium atom as a terminally bound κ¹-enamide (8 and 10), a bridging η³-1-azaallyl (6), or a bridging κ¹-enamide (5). The stereochemistry about the CC bond was Z for 5, 8 and 10 and E for 7. X-ray data are provided for 5, 6, 7, 8 and 10 and multinuclear NMR spectra data in C₆D₆ or C₆D₅CD₃ for each of 5-10.     

A contribution to 1-azapentadienylmetal chemistry: Si, Sn(II), Fe(II) and Co(II) complexes

Complexes of three related 1-azapentadienyl ligands [N(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R]⁻, abbreviated as L (R = Bu^t, R¹ = Me), L′ (R = Me = R¹), and L″ (R = Bu^t = R¹), are described. The crystalline compounds Sn(L)₂ (1), Sn(L′)₂ (2), [Sn(L′)(μ-Cl)]₂ (3) and [Sn(L″)(μ-Cl)]₂ (4) were prepared from SnCl₂ and 2 K(L), 2 K(L′), K(L′) and K(L″), respectively, in thf. Treatment of the appropriate lithium 1-azapentadienyl with Si(Cl)Me₃ yielded the yellow crystalline Me₃Si(L) (5) and the volatile liquid Me₃Si(L′) (6) and Me₃Si(L″) (7), each being an N,N,C-trisilyldieneamine. The red, crystalline Fe(L)₂ (8) and Co(L′)₂ (9) were obtained from thf solutions of FeCl₂ with 2 Li(L)(tmeda) and CoCl₂ with 2 K(L′), respectively. Each of 1-9 gave satisfactory C, H, N analyses; 6 and 7 (GC-MS) and 1, 2, 8 and 9 (MS) showed molecular cations and appropriate fragments (also 3 and 4). The ¹H, ¹³C and ¹¹⁹Sn NMR (1-4) and IR spectra support the assignment of 1-4 as containing Sn-N(SiMe₂R¹)-C(Bu^t)(CH)₃SiMe₂R moieties and 5-7 as N(SiMe₃)(SiMe₂R¹)C(Bu^t)(CH)₃SiMe₂R molecules; for 1-4 this is confirmed by their X-ray structures. The magnetic moments for 8 (5.56 μ_B) and 9 (2.75 μ_B) are remarkably close to the appropriate Fe and Co complex [M{η³-N(SiMe₃)C(Bu^t)C(H)SiMe₃}₂]; hence it is proposed that 8 and 9 have similar metal-centred, centrosymmetric, distorted octahedral structures.     

Neutral penta-coordinated diorganotin(IV) complexes derived from ortho-aminophenol Schiff bases: Synthesis, characterization and molecular structures

The one pot reactions carried among ortho-aminophenol, R₂SnO (R = Me or Ph) and acetyl acetone, 2-hydroxyacetophenone and 2-hydroxy-3-methylacetophenone led to six new diorganotin(IV) compounds Me₂SnL1 (1), Ph₂SnL1 (2), Me₂SnL2 (3) Ph₂SnL2 (4), Me₂SnL3 (5) and Ph₂SnL3 (6) (H2L1 = 2-(3-hydroxy-1-methyl-but-2-enylideneamino)-phenol, H2L2 and H2L3 = 2-[1-(2-hydroxyaryl)alkylideneamino]-phenol) in good yields. Combination of IR, ¹H, ¹³C and ¹¹⁹Sn NMR and X-ray diffraction techniques along with elemental analyses evidenced the formation of penta-coordinated monomeric species. The crystal structures of ligand H2L1 and complexes 1, 3 and 4 were determined by single crystal X-ray diffraction study. In the solid state, the ligand H2L1 exists as keto-enamine tautomeric form. There are N-H…O intra-molecular hydrogen bonds between amine and carbonyl groups. Diorganotin(IV) complexes 1, 3 and 4 are monomers with TBP (trigonal bipyramidal) geometry surrounding the tin atom. The O, N, O- tridentate ligand places its two oxygen donating atoms in the axial positions, and the nitrogen atom occupies one equatorial position. The two R groups attached to tin occupy the other two equatorial positions. The solution structures were predicted by ¹¹⁹Sn NMR spectroscopy.     

Studies on inverse electron demand hetero Diels-Alder reaction of perfluoroalkyl 2(1H) pyridones with different dienophiles under microwave irradiation

The reaction of N-acetyl perfluoroalkyl substituted 2(1H) pyridones (7) with dimethylacetylenedicarboxylate (DMAD) on neutral alumina under solvent free microwave irradiation conditions extended to undergo an inverse electron demand hetero Diels-Alder reaction, however resulted exclusively in E, Z isomers (3:1) of Michael-type N-adducts (8). The similar reaction in case of 7a under thermal and photochemical conditions also gave the same products.     

New group 14 element(IV) β-diiminates and a Sn(II) analogue

Seven group 14 element(IV) compounds 2-7 have been prepared, derived either (2-5) from the potassium β-diketiminate K(L) [L = {N(Ar)C(Me)}₂CH, Ar = C₆H₃Prⁱ₂-2,6] (1) or the known lithium β-dialdiminate Li(L′)] [L′ = {N(Ar)C(H)}₂CPh, Ar = C₆H₃Prⁱ₂-2,6]. Treatment of 1 with Bu^tC(O)Cl, Me₃SiCl, Ph₃SnCl, or Me₃SnCl afforded {N(Ar)C(Me)}₂C(H)C(O)Bu^t (2), [ArNC(Me)C(H)C(Me)N(Ar)SiMe₃] (3), [HN(Ar)C(Me)C(H)C(CH₂SnPh₃)N(Ar)] (4), or (5), respectively. Compounds 4 and 5 are remarkable as they have arisen from a tautomer of 1; crystalline centrosymmetric 5 has a fused tricyclic structure, a central eight-membered ring flanked by two six-membered rings. The compounds [GeCl₂(L′)(OGeCl₃)] (6) or [SnCl(L′)Me₂] (7), the first group 14 metal β-dialdiminates, were obtained from Li(L′) and (GeCl₃)₂O or Me₂SnCl₂, respectively. The Sn(II) compound SnCl(L′) (8) was prepared from SnCl₂ and K(L′). The molecular structures of the crystalline compounds 3-8 are reported.     

Osmium-carbonyl complexes of naphthylazoimidazoles. Single crystal X-ray structure of [Os(H)(CO)(PPh3)2(α-NaiEt)](PF6) {α-NaiEt = 1-ethyl-2-(naphthyl-α-azo)imidazole}

1-Alkyl-2-(naphthyl-α/β-azo)imidazole (α-NaiR 1; β-NaiR, 2) react with [Os(H)(Cl)(CO)(PPh₃)₃] in THF and synthesise [Os(H)(CO)(PPh₃)₂(α/β-NaiR)](PF₆) (3, 4). The X-ray structure of [Os(H)(CO)(PPh₃)₂(α-NaiEt)](PF₆) (3c) shows a distorted octahedral geometry. Other spectroscopic studies (IR, UV–Vis, NMR) support the stereochemistry of the complexes. Addition of Cl₂ in MeCN to 3 or 4 gives [Os(Cl)(CO)(α/β-NaiR)(PPh₃)₂](PF₆) (5, 6), which were characterized by spectroscopic studies. The redox properties of the complexes show Os(III)/Os(II), Os(IV)/Os(III) and azo reductions.     

Synthesis of trifluoromethylated heterocycles using partially fluorinated epoxides

Reaction of 2-trifluoromethyl- (1) and 2,2-bis(trifluoromethyl)- (2) oxiranes with a variety of sulfur nucleophiles proceeds rapidly and under mild conditions. For example, epoxide 2 reacts with aqueous solution of Na₂S, producing S[CH₂C(CF₃)₂OH]₂. Reaction of 2 with Na₂S₂O₃ leads to the formation of the corresponding Bunte salt. Interaction of 2 with NaSCN in water proceeds exothermically and results in high-yield formation of cyclic imine 5. Although this material can be isolated, it has limited stability and undergoes cyclotrimerization at ambient temperature, giving the corresponding 1,3,5-triazine. A number of heterocyclic compounds containing pendant -CH₂C(CF₃)₂OH group were prepared by the reaction of the corresponding thio-derivatives, such as pyridine-2-thiole with epoxide 2. It was found that fluoride anion catalyzes the reaction of epoxides 1 and 2 with isothiocyanates carrying electron withdrawing groups at nitrogen. The reaction results in nucleophilic cyclization and formation of the corresponding exocyclic imines containing a 1,3-oxothiolane moiety. Carbon disulfide was also found to be active in this process, reacting with epoxides 1 and 2 at ambient to give the corresponding trifluoromethylated 1,3-oxathiolane-2-thiones in 58-65% yield.     

Partial hydrogenation of substituted pyridines and quinolines: a crucial role of the reaction conditions

Hydrogenation of pyridyl and quinolyl compounds 2-substituted with a carbonyl group (1a-c and 2b,c) using PtO₂ and 1 equiv. of HCl (conditions A) provides clean and total formation of the desired amino alcohol (hydrogenation of the heterocyclic ring and of the carbonyl) while under conditions B₁ and/or B₂ (concentrated HCl or pure CF₃CO₂H) the heterocyclic ring remains untouched and other aromatic parts are hydrogenated providing complex mixtures. When the heterocyclic ring is substituted by an alkyl group (quinaldine 3) conditions A provide mixtures while under conditions B₂ (pure CF₃CO₂H) the benzene ring is cleanly hydrogenated leading to a pure product.     

Tin(IV) complexes obtained by reacting 2-benzoylpyridine-derived thiosemicarbazones with SnCl4 and Ph2SnCl2

Reaction of 2-benzoylpyridine thiosemicarbazone (H2Bz4DH, HL1) and its N(4)-methyl (H2Bz4Me, HL2) and N(4)-phenyl (H2Bz4Ph, HL3) derivatives with SnCl₄ and diphenyltin dichloride (Ph₂SnCl₂) gave [Sn(L1)Cl₃] (1), [Sn(L1)PhCl₂] (2), [Sn(L2)Cl₃] (3), (4) [Sn(L3)PhCl₂] (5) and [Sn(L3)Ph₂Cl] (6). Infrared and ¹H, ¹³C and ¹¹⁹Sn NMR spectra of 1-3, 5 and 6 are compatible with the presence of an anionic ligand attached to the metal through the N_py-N-S chelating system and formation of hexacoordinated tin complexes. The crystal structures of 1-3, 5 and 6 show that the geometry around the metal is a distorted octahedron formed by the thiosemicarbazone and either chlorides or chlorides and phenyl groups. The crystal structure of 4 reveals the presence of and trans [Ph₂SnCl₄]²⁻.     

Synthesis,crystal structure and reactivity of a new pentacoordinated chiral dioxomolybdenum(VI) complex

The novel tridentate chiral ligand 2,6-bis{[(1R,2S,4R)-2-hydroxy-1,3,3-trimethyl-bicyclo[2.2.1]hept-2-yl]}pyridine (1) was readily prepared by reaction of 2,6-dilithiopyridine with (R)-(−)-fenchone. Reaction of 1 with [MoO₂(acac)₂] resulted in the formation of the new metal-oxo five-coordinated complex [MoO₂(ONO)] (2) [ONO = (1 – 2H)]. The reactivity of 2 has been studied and the derivatives [MoS₂(ONO)] (3) and [MoO(O₂)(ONO)] (4) were prepared. The compounds 1–4 have been characterised by ¹H and ¹³C{¹H} NMR, microanalysis and IR spectroscopy. Furthermore, the molecular structures of 1 and 2 have been determined by single-crystal X-ray diffraction. The behaviour of 2 as catalyst in oxotransfer and in nucleophilic substitution of propargylic alcohols reactions has been tested.     

μ-Coordination chemistry of NO ligands: Adducts of trans-Mo(dmpe)2(H)(NO) with lithium salts

Four adducts were formed by the reaction of trans-Mo(dmpe)₂(H)(NO) (1) (dmpe = bis(dimethylphosphino)ethane) and a respective lithium reagent to afford, [Mo(dmpe)₂(H)(NO)LiHBEt₃]₂ (2), [Mo(dmpe)₂(H)(NO)LiN(SiMe₃)₂]₂ (3), [Mo(dmpe)₂(H)(NO)]₃(LiBH₄)₂ (4), and {[Mo(dmpe)₂(H)(NO)]₂[LiBH₄]₅}_n (5). Structures 2-5 were characterized by crystal X-ray diffraction analyses. Structures 2 and 3 revealed to be dimers of the 1:1 adduct of 1 and the lithium salt. The two nitrosyl oxygen atoms in 2 are μ₂-bridged connecting two separate LiHB(C₂H₅)₃ moieties, whereas in 3 these oxygen atoms exhibit a terminal coordination mode binding to two lithium ions of the dimeric [LiN(SiMe₃)₂]₂ unit. Structure 4 shows a discrete structure formed by two separate mononuclear LiBH₄ units being bridged by the nitrosyl oxygen atoms of three Mo(dmpe)₂(H)(NO) moieties. Structure 5 displays a complicated chain structure with differently coordinated lithium centers, various types of bridging BH₄ and bridging nitrosyl groups.     

Synthesis and reactivity of rhodium fluoro complexes

[RhH(CO)(PPh₃)₂] (1) reacts with Et₃N·3HF to give the fluoro compound [RhF(CO)(PPh₃)₂] (2). In a comparable reaction [RhF(PEt₃)₃] (5) has been obtained from [RhH(PEt₃)₃] (3) or [RhH(PEt₃)₄] (4) with substoichiometric amounts of Et₃N·3HF in THF. If the latter reaction is carried out in benzene, the complexes 5, cis-mer-[Rh(H)₂F(PEt₃)₃] (6) and cis-fac-[Rh(H)₂F(PEt₃)₃] (7) are obtained. Treatment of 5 with HCl in ether effects the generation of [RhCl(PEt₃)₃] (8) and the bifluoride compound [Rh(FHF)(PEt₃)₃] (9), which can be converted into 5 in the presence of Et₃N and Cs₂CO₃. Treatment of 5 with HSiR₂Ph (R=Ph, Me) leads to the formation of 3 and the rhodium(III) silyl complexes fac-[Rh(H)₂(SiR₂Ph)(PEt₃)₃] (10: R=Ph, 11: R=Me).     

Pd-catalyzed boronations and cross-coupling reactions of aromatic cobaltadithiolene complexes with aryl halides

The Pd-catalyzed reaction of [CpCo(S2C2(Ph)(Bpin))] (1, Bpin = 4,4,5,5-tetramethyl-1,3,2-dioxaboronate) with 1-iodonaphthalene or 2-bromothiophene gave the cross-coupling product [CpCo(S2C2(Ph)(Ar))] (Ar = 1-Np (4) or 2-Th (5)), although an early paper described the reaction of 1 with 3-bromopyridine or 9-bromoanthracene (Ar = 3-Py (2) or 9-Anth (3)). The boronation of the brominated precursor [CpCo(S2C2(p-C6H4Br)(H))] (7) with Bpin-H in the presence of Pd catalyst gave the expected boronated product [CpCo(S2C2(p-C6H4Bpin)(H))] (8) but also underwent an unexpected direct boronation on the dithiolene carbon to form [CpCo(S2C2(p-C6H4Br)(Bpin))] (9). The brominated complex 7 or [CpCo(S2C2(Ph)(p-C6H4Br))] (10) was synthesized by thermal reaction and the microwave-enhanced reaction relatively gave better yield with shorter reaction time than that of the conventional heating reaction. The cross-coupling reactions of the boronated or [CpCo(S2C2(Ph)(p-C6H4Bpin))] (11) with aryl halides successfully produced the corresponding cross-coupling products such as [CpCo(S2C2(p-C6H4Py)(H))] (12) or [CpCo(S2C2(p-C6H4Anth)(H))] (13) from 8 and [CpCo(S2C2(Ph)(p-C6H4Py))] (14) from 11. The structures of 7, 9, 11, 12, 13 and 14 were determined by X-ray diffraction studies. Electronic absorption maxima (λ_max) due to dithiolene LMCT in dichloromethane solution can be modified in the range of 574-602 nm by a substituent effect on the dithiolene ring. Redox potentials obtained from CV measurement were also reported.     

Increasing the antibacterial activity of gallium(III) against Pseudomonas aeruginosa upon coordination to pyridine-derived thiosemicarbazones

Reaction of N(4)-phenyl-2-formylpyridine thiosemicarbazone (H2Fo4Ph), N(4)-phenyl-2-acetylpyridine thiosemicarbazone (H2Ac4Ph) and N(4)-phenyl-2-benzoylpyridine thiosemicarbazone (H2Bz4Ph) with gallium nitrate gave [Ga(H2Fo4Ph)₂](NO₃)₃ (1), [Ga(2Ac4Ph)₂]NO₃ (2) and [Ga(2Bz4Ph)₂]NO₃ (3). In all complexes coordination of the thiosemicarbazone via the N_py–N–S chelating system occurs. In 1 the thiosemicarbazone acts as a neutral ligand while in 2 and 3 the ligand is anionic. Upon slow diffusion of 2 in DMSO [Ga(2Ac4Ph)₂]NO₃·DMSO (2a) was formed. The crystal structure of 2a was determined. Upon coordination the antibacterial activity of both gallium and thiosemicarbazones against Pseudomonas aeruginosa significantly increases.