Mohammad El-khateeb

Sulfur(IV) compounds as ligands: Part XXV. Halfsandwich ruthenium thiosulfonato complexes. Crystal and molecular structure of [CpRu(dppe){SSO2(4-C6H4Cl)}]

Abstract Reaction of the hydrogen sulfido complexes [CpRu(PP)(SH)] (PP=dppm (1), dppe (2)) with sulfonyl chlorides RSO2Cl at −70°C in THF gave the ruthenium thiosulfonato complexes [CpRu(PP)(SSO2R)] (PP=dppm (3), dppe (4), R=Me (a), Ph (b), 4-C6H4Cl (c), 4-C6H4NO2 (d)). The structure of 4c was determined by X-ray crystallography. Important molecular geometry data are: RuS(1) 239.3(2), S(1)S(2) 203.2(2), S(2)O(1) 145.0(5), S(2)O(2) 144.1(5) pm; RuS(1)S(2) 104.23(8)°.

Half sandwich iron S-bonded mono-thiocarbonate complexes: structure of CpFe(CO)2SCO2Et

Abstract The synthesis and characterization of mononuclear iron complexes containing mono-thiocarbonate ligands are described. The new compounds of general formula CpFe(CO)2SCO2R [R=Et (1), iso-Bu (2), Ph (3), 4-C6H4NO2 (4), Me (5)] were prepared by reacting the iron sulfides (μ-Sx)[CpFe(CO)2]2 (x=2, 3) with the corresponding chloroformates (ROCOCl). These new complexes have been characterized by elemental analyses and spectroscopic methods. The crystal structure of CpFe(CO)2SCO2Et, 1, has been determined by single crystal X-ray diffraction analysis.

The synthesis and structure of the thiosulfonato iron complexes CpFe(CO)2SS(O)2R

Abstract Treatment of the iron polysulfanes (μ-Sx)[CpFe(CO)2]2 (x=3, 4) with sulfonyl chlorides RSO2Cl (R=CF3 (1), CCl3 (2), C6F5 (3)) gave the corresponding iron thiosulfonato complexes CpFe(CO)2SS(O)2R in good yields. Crystal structure for 2: P21/c, a=6.704(2), b=8.933(2), c=22.603(5) A, α=90, β=92.82(2), γ=90°, V=1352.0(6) A3 and Z=4.

The first selenosulfonate complexes CpFe(CO)2SeSO2R: preparation and structure of CpFe(CO)2SeSO2C6H5

Treatment of the iron selenide (μ-Se)[CpFe(CO) 2 ] 2 with sulfonyl chlorides RSO 2 Cl (R=C 6 H 5 ( 1 ), 4-C 6 H 4 Cl ( 2 ), 4-C 6 H 4 Br ( 3 ), 4-C 6 H 4 t Bu ( 4 ), 4-C 6 H 4 Me ( 5 ), CH 3 ( 6 )) gave the novel iron selenosulfonato complexes CpFe(CO) 2 SeSO 2 R in good yields. The crystal structure for 1 was determined.

Ruthenium heterocyclic thiolate complexes: CpRu(L)(L′)SR, [L = L′ = PPh3, 1/2 dppm, 1/2 dppe; L = PPh3, L′ = CO]

The synthesis and characterization of several new ruthenium complexes containing heterocyclic thiolate ligands are described. CpRu(PPh3)2Cl reacts with thiolate anions to give CpRu(PPh3)2SR, (1) [R = 2-mercaptobenzimidazolyl (a), 2-mercaptobenzothiazolyl (b), and 2-mercaptobenzoxazolyl (c)] in good yields. The CpRu(PPh3)-(CO)SR (2) complexes are obtained by treating (1) with CO gas in THF at room temperature. The one-pot reaction of CpRu(PPh3)2Cl, thiolate anions with chelate bisphosphine ligands (P–P), gave CpRu(P–P)SR where P–P = Ph2PCH2PPh2 (dppm) (3); Ph2PCH2CH2PPh2 (dppe) (4).

Photolytic CO-substitution reaction of organoiron thiocarboxylate derivatives CpFe(CO)2SCOR (R=alkyl, aryl) with diphosphines (Ph2P(CH2)nPPh2) (n=1–6): X-ray crystal structure of [CpFe(dppm)SCO(3,5-(NO2)2C6H3)]

Abstract The photolytic CO-substitution reaction of the organoiron thiocarboxylate complexes CpFe(CO)2SCOR (R=CH3, 2-CH3C6H4, 2-NO2C6H4, 4-NO2C6H4, 3,5-(NO2)2C6H3) with diphosphines (Ph2P(CH2)nPPh2) [n=1 (dppm), n=2 (dppe), n=3 (dpppr), n=4 (dppb), n=5 (dppp), n=6 (dpph)] at room temperature using 1:2 (metal–ligand) molar ratio afforded exclusively the disubstituted complexes CpFe(Ph2P(CH2)nPPh2)SCOR when n=1, 2 and 3 and the monosubstituted analogs CpFe(CO)(Ph2P(CH2)nPPh2)SCOR when n=4, 5 and 6. This reaction was found to be strongly influenced by the backbone length of the diphosphine ligand, the nature of the R group of the thiocarboxylate moiety and the metal–ligand molar ratios. The crystal structure of CpFe(dppm)SCO(3,5-(NO2)2C6H3) was determined.

[FeFe]-Hydrogenase H-Cluster Mimics with Unique Planar (µ-SCH2)2ER2 Linkers (E = Ge and Sn).

Analogues of the [2Fe-2S] subcluster of hydrogenase enzymes in which the central group of the three-atom chain linker between the sulfur atoms is replaced by GeR2 and SnR2 groups are studied. The six-membered FeSCECS rings in these complexes (E=Ge or Sn) adopt an unusual conformation with nearly co-planar SCECS atoms perpendicular to the Fe-Fe core. Computational modelling traces this result to the steric interaction of the Me groups with the axial carbonyls of the Fe2 (CO)6 cluster and low torsional strain for GeMe2 and SnMe2 moieties owing to the long C-Ge and C-Sn bonds. Gas-phase photoelectron spectroscopy of these complexes shows a shift of ionization potentials to lower energies with substantial sulfur orbital character and, as supported by the computations, an increase in sulfur character in the predominantly metal-metal bonding HOMO. Cyclic voltammetry reveals that the complexes follow an ECE-type reduction mechanism (E=electron transfer and C=chemical process) in the absence of acid and catalysis of proton reduction in the presence of acid. Two cyclic tetranuclear complexes featuring the sulfur atoms of two Fe2 S2 (CO)6 cores bridged by CH2 SnR2 CH2 , R=Me, Ph, linkers were also obtained and characterized.

Synthesis, Characterization, and Some Properties of 4-Vinylpyridine-Cr(CO)5 Containing Polymers

The polymerization of 4-vinylpyridine (4VP) and 4-vinylpyridine chromium pentacarbonyl [(4VP)Cr(CO)5] was performed under N2 atmosphere at 60–80°C temperature range. Different percent of feed (%PF) of Cr(CO)5 groups were anchored into poly(4-vinylpyridine) (P4VP) by addition of the intermediate Cr(CO)5THF, which was generated photochemically from Cr(CO)6 in THF, to the polymer at ambient temperature. The determined percent of anchoring (%PA) has shown that the maximum anchored Cr(CO)5 groups was 40% (w/w) with respect to P4VP, and the optimum percent of anchoring was 20% (w/w). The rate of polymerization (Rp) and the activation energy (Ea) of 4VP in the absence and in the presence of 16.7% Cr(CO)5(4VP) were determined. Thermal analysis has shown various changes in the properties of the 4VP polymers after modification of the polymer by Cr(CO)5 groups. The X-ray diffraction and the melting enthalpy derived from the DSC thermogram revealed that the synthesized poly[(CO)5Cr(4VP)] has a crystallinity of about 40%, whereas no crystallinity was observed for pure P4VP.

The reactions of CpRu(PPh3)2SR with the electrophiles HBF4, [MeSSMe2]BF4 and MeSphth where R=CMe3, CHMe2, 4-C6H4Me and phth=phthalimide

Abstract Reaction of the ruthenium thiolato complexes CpRu(PPh3)2SR (1), where R=CMe3, CHMe2, 4-C6H4Me with HBF4 gave the corresponding thiol complex salts [CpRu(PPh3)2(HSR)]BF4 (2) in very good yields. Treatment of the thiolato complexes with [MeSSMe2]BF4 gave the methyl thioether complex salt [CpRu(PPh3)2SMe2]BF4 (3). Reactions of 1 with MeSphth, where phth=phthalimide, gave CpRu(PPh3)2(phth) (4) and the dimers (μ-SMe)(μ-SR)[CpRu(phth)]2 (5) for R=CMe3 and CHMe2, however, for R=4-C6H4Me the same reaction gave CpRu(PPh3)(phth)(MeSS-4-C6H4Me) (6) and (μ-SMe)(μ-S-4-C6H4Me)[CpRu(S-4-C6H4Me)]2 (7). The crystal structure for 7 was determined: space group P21/c, a=8.805(2), b=13.668(3), c=26.026(6) A, α=90, β=108.86(2), γ=90°, V=2964.0(12) A3 and Z=4.

[FeFe]-Hydrogenase H-Cluster Mimics with Various −S(CH2)nS– Linker Lengths (n = 2–8): A Systematic Study

The effect of the nature of the dithiolato ligand on the physical and electrochemical properties of synthetic H-cluster mimics of the [FeFe]-hydrogenase is still of significant concern. In this report we describe the cyclization of various alkanedithiols to afford cyclic disulfide, tetrasulfide, and hexasulfide compounds. The latter compounds were used as proligands for the synthesis of a series of [FeFe]-hydrogenase H-cluster mimics having the general formulas [Fe2(CO)6{μ-S(CH2)nS}] (n = 4-8), [Fe2(CO)6{μ-S(CH2)nS}]2 (n = 6-8), and [Fe2(CO)6{(μ-S(CH2)nS)2}] (n = 6-8). The resulting complexes were characterized by 1H and 13C{1H} NMR and IR spectroscopic techniques, mass spectrometry, and elemental analysis as well as X-ray analysis. The purpose of this research was to study the influence of the systematic increase of n from 2 to 7 on the redox potentials of the models and the catalytic ability in the presence of acetic acid (AcOH) by applying cyclic voltammetry.