Cristian Silvestru

Metal compounds in cancer chemotherapy

Revue synthetique de complexes metalliques utilisables en chimiotherapeutique. Synthese bibliographique

Tetraorganodichalcogenoimidodiphosphorus acids and their main group metal derivatives

Abstract The review is focused on the (XPR 2 )(YPR′ 2 )NH acids (X, Y=O, S, Se; R, R′=alkyl, aryl, OR) and their main group metal derivatives. The methods of preparation, spectroscopic studies and molecular structures of known imidodiphosphorus acids and related derivatives as well as those of inorganic and organometallic main group metal complexes containing either protonated or deprotonated imidodiphosphorus ligand moieties are systematized and discussed.

Structural patterns in inorganic and organoantimony derivatives of oxo- and thiodiorganophosphorus ligands

Abstract The structures of inorganic and organoantimony complexes of diorganophosphorus ligands and their thio analogues, determined by X-ray diffraction, are reviewed with particular attention given to the coordination geometry around the metal atom and the coordination pattern of the phosphorus ligands.

Hypervalent organotin(IV) derivatives containing [2-(Me2NCH2)C6H4]Sn moieties. Competition between nitrogen and chalcogen atoms for coordination to the metal centre

Abstract [2-(Me2NCH2)C6H4]SnPh2Cl (1) was prepared by reacting Ph2SnCl2 with [2-(Me2NCH2)C6H4]Li in toluene. The reactions of (1) with the ammonium salt of the appropriate thiophosphinato ligand in 1:1 molar ratio afford the isolation of [2-(Me2NCH2)C6H4]SnPh2L [L=S(S)PPh2 (2), O(S)PPh2 (3)] as white crystalline solids. The molecular structure of 1–3 was determined by single-crystal X-ray diffraction. Their crystals contain monomeric units with the metal atom exhibiting a distorted trigonal bipyramidal coordination environment. The SnC3 moiety is almost planar. The N atom of the pending CH2NMe2 arm is strongly coordinated to the metal centre (Sn(1)N(1) 2.519(2), 2.548(3), 2.481(2) A for 1, 2 and 3, respectively), trans to the Cl, O or S atoms (N(1)Sn(1)Cl(1) 170.49(6)°, N(1)Sn(1)S(1) 169.06(8)°, N(1)Sn(1)O(1) 168.58(8)°, respectively). The S atom double bonded to phosphorus is not involved in intra- or intermolecular coordination to tin.

Experimental and theoretical evidence of the first Au(I)⋯Bi(III) interaction

Complex [Au(C6F5)2][Bi(C6H4CH2NMe(2)-2)2] displays the first example of an interaction between Au(I) and Bi(III), the nature of which is shown to be consistent with the presence of a high ionic contribution (79%) and a dispersion type (van der Waals) interaction (21%).

Crystal and molecular structure of 1-phenyl-1H-tetrazole-5-thiolato-trimethyltin(IV), Me3SnSCN4Ph, exhibiting unusual trimeric associations through intermolecular N → Sn bonds.

Abstract The title compound is rhombohedral, space group R3, with a = 18.097(4), c = 10.832(5) A, Z = 9, Dc = 1.658 g cm−3. The crystal contains trimeric [Me3SnSCN4Ph]3 units in which the heterocyclic ligand is bridging two metal atoms (Sn(1)-S(1) 2.565(4) A, N(3) → Sn(1a) 2.747(14) A). Additionally, weak intramolecular Sn(1) ⋯ N(4) secondary bonds of 3.285(12) A are also present, thus leading to a bimetallic triconnective coordination pattern of the ligand.

Diorganotin(IV) derivatives of tetraphenylimidodiphosphinic acid. Crystal and molecular structure of n-Bu2Sn[(OPPh2)2N]2, a trans-octahedral spiro-bicyclic compound

Abstract Bis(tetraphenylimidodiphosphinato)diorganotin(IV) derivatives, R 2 Sn[(OPPh 2 ) 2 N] 2 (R = Me, n-Bu, Bz, Ph), were prepared by reacting the appropriate R 2 SnCl 2 with the sodium salt of the phosphorus acid. The compounds were characterized by IR, 1 H, 13 C and 31 P NMR. The crystal and molecular structure of n-Bu 2 Sn[(OPPh 2 ) 2 N] 2 was determined by X-ray diffractometry. The imidodiphosphinato ligands are isobidentate [SnO(1) 2.204(5), SnO(2) 2.202(5), P(1)O(1) 1.520(6) and P(2)O(2) 1.527(6) A]. In the spiro-bicyclic NP 2 O 2 SnO 2 P 2 N system the trans OSnO angles are 180.0(0)°, while the cis OSnO angles are 88.5(2)° (endocyclic) and 91.5(2)° (exocyclic). The SnC 2 moiety is co-linear [CSnC 180.0(0)°] and almost perpendicular to the SnO 4 plane, thus leading to a quasi perfect trans -octahedral geometry around the central metal atom. The structure is compared with that of the previously reported cis -octahedral I 2 Sn[(OPPh 2 ) 2 N] 2 .

New organotin(IV) derivatives of 1-phenyl-1H-tetrazole-5-thiol. Crystal and molecular structure of 1∞[Bz3SnSCN4Ph], a polymer built through secondary intermolecular Sn⋯N bonds

Abstract Di- and triorganotin(IV) derivatives of 1-phenyl-1H-tetrazole-5-thiol, RnSn(SCN4Ph)4−n (R = Me, Bz; n = 2, 3), were prepared by reacting the corresponding organotin chlorides with the ammonium salt of the thiotetrazolato anion. The title compounds were characterized by means of IR and 1H, 13C and 119Sn NMR spectroscopy. The molecular structure of Bz3SnSCN4Ph was investigated using X-ray diffractometry. Data on a redetermination of the crystal and molecular structures of n-Bu2Sn(SCN4Ph)2 are also included, and a comparative discussion of the two structures is presented.

Metallophilic bonding and agostic interactions in gold(I) and silver(I) complexes bearing a thiotetrazole unit.

Gold(I) and silver(I) complexes of 1-methyl-5-thio-tetrazole (1) have been prepared and the coordination chemistry of this ligand toward metal-phosphine frameworks has been explored. As indicated by IR and Raman data, ligand 1 is deprotonated and the resulted anion acts as a bidentate (S,N)-tetrazole-5-thiolato unit in the new gold(I) complexes, [Au(SCN(4)Me)(PPh(3))] (2), [{Au(SCN(4)Me)}(2)(μ-dppm)] (3), and [{Au(SCN(4)Me)}(2)(μ-dppe)] (4), while it is coordinated only through the sulfur atom as its neutral tetrazole-5-thione form in the silver(I) derivative, [Ag(HSCN(4)Me)(PPh(3))](2)(OTf)(2) (5). Further characterization of the new compounds was performed using multinuclear ((1)H, (13)C, (31)P, (19)F) NMR spectroscopy, mass spectrometry, and DSC measurements. Single-crystal X-ray diffraction studies revealed basically linear P-M-S arrangements in complexes 3-5. The bidentate (S,N) coordination pattern results in a T-shaped (S,N)PAu core in 3 and 4, whereas, in 5, a similar coordination geometry is achieved in the dimer association based on S-bridging ligand 1. Herein, weak (C)H···Au and (C)H···Ag agostic interactions were observed. An intramolecular Au···Au contact occurs in 3, while in 4 intermolecular aurophilic bonds lead to formation of a chain polymer. An intermolecular Ag···Ag contact is also present in the dimer unit of 5. Low-temperature (31)P NMR data for 5 evidenced the presence of monomer and dimer units in solution. Theoretical calculations on model of the complexes 2 and 4 are consistent with the geometries found by X-ray diffraction studies.

Synthesis, spectroscopic characterization and crystal and molecular structure of tetrakis(carbonyl)(tetraphenyldithioimidodiphosphinato) manganese(I), Mn(CO)4[(SPPh2)2N]

Abstract Mn(CO) 4 [(SPPh 2 ) 2 N] was prepared by allowing [Mn(CO) 5 ]Br to react with K[SPPh 2 ) 2 N], in THF. The compound was characterized by IR, mass and NMR ( 1 H, 13 C, 31 P) spectroscopy, and its crystal and molecular structure was determined by single-crystal X-ray diffraction. The lattice contains two independent, monomeric molecules, ( 1 ) and ( 1a ). The metal atom has a distorted octahedral coordination geometry (C ax MnC ax 175.9(3)° in ( 1 ), 176.9(3)° in ( 1a )), with two carbonyl groups and the two sulfur atoms of the symmetric monometallic bidentate (mean PS 2.021(2) A in ( 1 ), 2.020(2) A in ( 1a )) dithio ligand unit in equatorial positions (mean MnS 2.420(2), MnC eq 1.804(4), MnC ax 1.855(5) A in ( 1 ), MnS 2.417(2), MnC eq (2) MnC ax 1.862(5) A in ( 1a )). The main difference between the two independent molecules is the conformation of the inorganic MnS 2 P 2 N chelate ring.