CHOOSE YOUR CURRENCY


ALKYLATION OF [PT2(µ-S)2(PPH3)4] WITH BORONIC ACID DERIVATIVES BY PRESSURIZED SAMPLE INFUSION ELECTROSPRAY IONIZATION MASS SPECTROMETRY (PSI- ESI-MS) TECHNIQUE

Amount: ₦5,000.00 |

Format: Ms Word |

1-5 chapters |



ABSTRACT

This project work present the alkylating reaction  of  [Pt2(μ-S)2(PPh3)4]  with boronic acid alkylating agents.The reactivity of the metalloligand [Pt2(μ-S)2(PPh3)4] with the boron-functionalized alkylating agents BrCH2(C6H4)B(OR)2  (R = H or C(CH3)2) was investigated by electrospray ionization mass spectrometry (ESI-MS) in real time using the pressurized sample infusion (PSI). The macroscopic reaction of [Pt2(μ-S)2(PPh3)4] with  one  mole   equivalent of alkylating agents BrCH2(C6H4)B{OC(CH3)2}2and BrCH2(C6H4)B(OH)2   gave the dinuclear  monocationic  µ-sulfide thiolate  complexes

[Pt2(µ-S){µ-SCH2(C6H4)B{OC(CH3)2}2}(PPh3)4]+              and          [Pt2(µ-S){µ-S+CH2

(C6H4)B(OH)(O–)}(PPh3)4].   The  products  were  isolated  as  the  [PF6]–   salts  and zwitterion  respectively,  and fully characterized  by ESI-MS,  IR, 1H and 31P  NMR

spectroscopy  and  single  crystal  X-ray  structure  determinations.   The   alkylation reaction of BrCH2(C6H4)B{OC(CH3)2}2   with [Pt2(µ-S)2(PPh3)4  + H]+was determined via kinetic analysis by PSI-ESI-MS to be second order consistent with the expected SN2  mechanism  for  an alkylation  reaction.  The  PSI-ESI-MS  microscale  synthesis

showed   that[Pt2(µ-S)2(PPh3)4]disappeared   rapidly  with  consequent   formation   of onlymonoalkylated                    cationic                    product,                    [Pt2(µ-S){µ- SCH2(C6H4)B{OC(CH3)2}2}(PPh3)4]+.    This   was   indicated    by   the   immediate appearance of the monoalkylated  product peak at m/z  1720.6.The  reaction came to completion  within 6 minutes after  injection  and  no  trace of any other product  or dialkylated species. The desk top synthesis observed after further stirring for six hours also show the formation of no other  product. The reaction ofBrCH2(C6H4)B(OH)2, with({[Pt2(µ-S)2(PPh3)4] + H}+)within same time interval yielded three monocationic species that were detected by ESI-MS and assignable to the three alkylated products: [Pt2(µ-S){µ-SCH2C6H5)(PPh3)4]+,  m/z  1593.4  from  the  loss  of  B(OH)2   moiety;  a

hemiketal-like species [Pt2(µ-S){µ-SCH2(C6H4)B(OH)(OCH3)}(PPh3)4]+, m/z 1651.5 and   [Pt2(µ-S){µ-SCH2(C6H4)OH}(PPh3)4]+,    m/z   1609.5.   The   laboratory   scale

synthesis indicated the same products.The masses were identified by comparing the experimental  isotope patterns with calculated  ones. No   peak was observed  in the mass spectrum that was attributable to the formation of the expected product [Pt2(µ-

S){µ-SCH2(C6H4)B(OH)2}(PPh3)4]+.     The    structural    determination    by    X-ray

diffraction showed  that the compound formed was a zwitter ion (neutral  complex) [Pt2(µ-S){µ-S+CH2(C6H4)B(OH)(O-)}(PPh3)4].     [Pt2(µ-S){µ-S+CH2(C6H4)B(OH)(O-

)}(PPh3)4] is a neutral species and not detectable in ESI-MS. 1H NMR spectra showed a  complicated   set  of  resonances   in  the  aromatic  region  due  to   the   terminal triphenylphosphine  ligands  and  were  broadly  assigned  as  such.  However,  SCH2 hydrogen atoms were easily identified as broad peaks at δ 3.59 ppm and 3.60 ppm for [Pt2(µ-S){µ-SCH2(C6H4)B{OC(CH3)2}2}(PPh3)4]+PF6 and [Pt2(µ-S){µ- S+CH2(C6H4)B(OH)(O-)}(PPh3)4],  respectively.  The monoalkylated  products  shows IR and 31P{1H} NMR spectra expected of the complexes. The OH vibration (3336 cm-

1) in 2.1 shifted to 3435 cm-1  in 2.1a. The absorption bands of  the B-O bond in 2.2

(1355 cm-1) and 2.1 (1350 cm-1) shifted to  1360 cm-1 and 1367 cm-1 in 2.2a·(PF6) and

2.1a respectively.  The 31P{1H} NMR  spectra  showed  nearly superimposed  central resonances  and clearly separated  satellite peaks due to 195Pt coupling.  The 1J(PtP) coupling  constants  showed  the  differences  due  to  the  trans  influences  of  the

substituted   and  the  unsubstituted   sulfide  centers.   The  trans  influence   of   the unsubstituted sulfide is greater than the thiolate (substituted) species demonstrated by the coupling constants at (2628 and 3291 Hz) for 2.2a·(PF6) and (2632 and 3272 Hz)

2.1a,respectively.

CHAPTER ONE

1.0      Introduction

1.1      Background of Study

The diverse study on platinum and sulfur element has been possible due to their rich individual chemistries.Their  compounds have been extensively studied due  to their wide  range  of  applications  in  both  biology  and  industry1.     Platinum  was  first discovered  in 1735 by Don Antonio  de Ulloa. It has high melting  point and good resistance  to corrosion and chemical attack2. Consequence  to its  resistance  to wear and tarnish and its beautiful looks, it is employed in jewellery production3,4. It is also used  in  laboratory  equipment,  electrical  contacts,   catalytic  converters,  dentistry equipment, electrodes, antioxidation processes, catalysis, biomedical applications and hard disk4,5,6,7, 8-11. Platinum compounds like cisplatin, carboplatin and oxaliplatin are

used  in  cancer  treatments12,13,14.  The  use  of  cisplatin  in  cancer  chemotherapy  is limited by ototoxicity, emetogenesis effect, neurotoxicity, and nephrotoxicity of the drug15-18. It has been suggested that the toxicity of the drug is as a result of bonding between platinum and protein sulfur atoms19.

Platinum  exists  in different  oxidation  states,  0  to  +6,  due to  its vacant  d orbitals. The most common oxidation state is +2 including non-even20  with +1 and +3 found in dinuclear   Pt-Pt bonded complexes. These properties make  platinum form

coordination compounds easily.

Sulfur  is commonly  used  in the manufacturing  of important  chemical  like sulfuric acid. It is also used to refine oil and in processing ores11. It is an essential element  in most  biochemical  processes.  Sulfur  compounds  serve  as  substrates  in biochemical  process  (serving  as  an  electron  acceptor  in  anaerobic  respiration  of

sulfate-sulfur eubacteria), fuels (electron donors) and respiratory (oxygen alternative) in metabolism22. Vitamins such as thiamine and biotin, antioxidants like thioredoxin and glutathiones, and myriads of enzymes contain organic sulfur23. Organic sulfur has an anti-neoplastic effect and used in oral and other cancers treatment24.

Sulfur ligands coordinate  with most transition  metals  in different  oxidation states25.  The  chemical  properties  of  sulfur  as  a  versatile  coordination  ligand  is illustrated by its tendency to extend its coordination  from  terminal groups example ([Mo2S10]2-)26  to μ-sulfido  group e.g.  [Pt2(µ-S)2(PPh2Py)4]27  and to an encapsulated

form  e.g.  [Rh17(S)2(CO)32]3-      consisting  of  a  S-Rh-S  moiety  in  the  cavity  of  a

rhodium-carbonyl   cluster28.  It  has  the  propensity  to  catenate  and  give  rise   to 2- polysulfide  ligands  (Sn
) with n ranging  from 1 to 8. Sulfur ligands  coordination

chemistry is widely manifested in the variety of structures it forms with most of the transition  metals25.  The  important  roles  of  metal  sulfide  compounds  are  seen  in catalysis29, bioinorganic and rich solid-state chemistry 30. The  metal-sulfur bonding serves  as  key  part  of  the  active  site  component  in  reactivity  of  the  biological macromolecule31-35.

{Pt2S2} chemistry is dated back to 1903 when Hofmann and Hochlen reported a  work  on  isolation  of  the  first  platinum-sulfur  complex  [(NH4)2[Pt(η2-S5)3]36. Platinum  sulfido  complexes  are classified  as homometallic  sulfido  complexes  and heterometallic sulfido complexes. The homometallic sulfido complex of platinum was further  classified  into  groups  consisting  of  the  platinum  atom  metal-metal  bond bridged by single sulfur, and that in which the two non-bonded platinum atoms are held together by two sulfur ligands. The sulfur  atoms, in both complexes  have the capability of bonding further to other metals or ligands. Following the development reported by Hofmann and Hochlen in  1903, a metal-metal bond bridged by single sulfur  complex [Pt2(µ-S)(CO)2(PPh3)3]  was reported by Baird  and Wilkinson  as  a product of the reaction  of [Pt(PPh3)3]  with COS37. On heating  in  chloroform,  the intermediate  [Pt(PPh3)2(COS)]  gave  an  orange  air-stable   compound  which  was identified  using  infra-red  spectroscopy  and  elemental  analysis  technique38.  X-ray crystallography showed that the compound had only one CO ligand and the structure was reported by Skapski and Troughton39.



This material content is developed to serve as a GUIDE for students to conduct academic research


ALKYLATION OF [PT2(µ-S)2(PPH3)4] WITH BORONIC ACID DERIVATIVES BY PRESSURIZED SAMPLE INFUSION ELECTROSPRAY IONIZATION MASS SPECTROMETRY (PSI- ESI-MS) TECHNIQUE

NOT THE TOPIC YOU ARE LOOKING FOR?



Project 4Topics Support Team Are Always (24/7) Online To Help You With Your Project

Chat Us on WhatsApp »  09132600555

DO YOU NEED CLARIFICATION? CALL OUR HELP DESK:

   09132600555 (Country Code: +234)
 
YOU CAN REACH OUR SUPPORT TEAM VIA MAIL: [email protected]


Related Project Topics :

Choose Project Department