Transition Metal Zwitterionic Thiolate Complexes: Synthesis, Crystal Structures And Properties

In recent years, the chemistry of transition metal zwitterionic thiolate complexeshas attracted considerable attention due to their remarkable structural diversity and theirapplications in biological system and advanced materials. We have been interested inthe preparation of group IB and IIB, Pb and Bi metal complexes of a zwitterionicthiolate,4-（trimethylammonio） benzenethiol （TabH） which bears an ammonium groupand a sulfhydryl group and to some extent is similar to cysteine. However, the reactivityof these complexes is less explored. In this thesis, some M/Tab precursor complexeswere selected as model complexes to react with some P or N-donor ligands or cobaltions and a series of new metal zwitterionic thiolate compounds were isolated. We alsocarried out the reaction of TabHPF₆with MeHgI and demonstrated the reactivity of theresulting products towards other donor ligands in order to explore the mechanism of thecleavage of Hg-C bond. Over38metal complexes of the Tab ligand were isolated andstructurally characterized. The formation of these complexes may broaden the chemistryof the M/Tab complexes. The luminescent properties of some compounds in solid statewere also investigated. Studies on the reactivity of Zn（Cd）/Tab complexes may providesome insight into the varieties of coordination spheres of metal sites in MT whenN-donor ligands, N-heterocyclic compounds or other biobases or other metal ions areencountered in nature. Studies on the reactivity of MeHg compound may provide asimple approach to detoxification of organomercury compounds. The main results werebriefly described as follows:1. Reactions of [Au（Tab）₂]₂（PF₆）₂with dppe, dppp or dppb in different solventsgave rise to three one-dimensional complexes [Au₂（Tab）₂（dppe）]₂（PF₆）₄·2MeOH （1）,[Au₂（Tab）₂（dppp）]Cl₂·0.5MeOH·4H₂O （2）,[Au₄（μ-Tab）₂（Tab）₂（dppb）]（PF₆）₄·4DMF （3）,and a tetranuclear complex [Au₂（μ-Tab）（Tab）₂]₂Cl₄·2DMF·4H₂O （4）. The higheremission energy trend is1>2>3, which is in line with the decrease of （CH2）nlength ofthe diphosphines and their lifetimes. 2. Reactions of AgX （X=Cl, I） and TabHPF₆gave rive to two one-dimentionalcomplexes {[Tab-Tab][Ag₂Cl₄]2MeCN}n（5） and [TabH][AgI2]（6）. When[Ag（Tab）₂]（PF₆） was reacted with dppp or dppb, Tab ligands will be partially replacedby phosphine ligands to afford a pentanuclear compound [Ag₅（μ-Tab）₄（dppp）₄]（PF₆）5（7）and a dimeric compound [Ag2（μ-Tab）₂（dppb）2]（PF₆）₂6CH3CN （8）.3. Reactions of PdCl2·2H₂O with TabHPF₆in the presence or absence of a series ofphosphine ligands （PPh3, dppm, dppe, dppp, dppb, dppeda or dpppda） afforded a familyof palladium（II） thiolate compounds,[Pd₂（μ-Tab）₂Cl₄]（9）,[Pd₂（Tab）₄（μ-Tab）₂]Cl₄（10）,[Pd₂（PPh₃）₂（Tab）₂（μ-Tab）₂]（PF₆）₄（11）,[Pd₂（dppm）2（Tab）₂（μ-Tab）]（PF₆）₄（12）,[Pd₂（dppb）（Tab）₂（μ-Tab）₂]Cl₄（13）,[PdL（Tab）₂]（PF₆）₂（14: L=dppe;15: L=dppp）,{[PdL（Tab）₂]₂}Cl₄（16: L=dppeda；17: L=dpppda）. From the results of positive-ionESI mass spectra for9-17, we concluded that the cationic frameworks of themononuclear compounds14,15and the binuclear compounds16and17that arestrongly chelated by phosphine ligands were retained in MeCN. For the binuclearcompounds like9-13, their frameworks were no longer maintained under the massconditions that may be due to the relatively weak bond of Pd and μ-Tab.4. Reactions of Cd（NO₃）₂·4H₂O with TabHPF₆and Et3N in the presence ofN-donor ligands gave rise to six Cd（II）/thiolate complexes of N-donor ligands,[Cd₂（μ-Tab）₄（NCS）2]（NO₃）₂·MeOH （18）,[Cd₂（μ-Tab）₂（L）4]（PF₆）₄（19: L=2,2′-bipy;20:L=phen）,[Cd（Tab）₂（L）]（PF₆）₂（21: L=2,9-dmphen;22: L=bppy）,[Cd₂（μ-Tab）₂（Tab）₂（bdmppy）]2（PF₆）₈·H₂O （23）, while the reactions of [Zn（Tab）₄]（PF₆）₂with2,2′-bipy, phen,2,9-dmphen, N-Meim and bppy or with CoCl2·6H₂O at thepresence of N-donor ligands gave rise to nine zinc or cobalt thiolate complexes,[Zn（Tab）₂（L）]（PF₆）₂（24: L=2,2′-bipy;25: L=phen;26: L=2,9-dmphen;27: L=bppy;28: L=dmbppy），[Co（Tab）₂（L）₂]（PF₆）₃（29: L=2,2′-bipy;30: L=phen;31: L=4,4′-dmbpy） and [Co（Tab）（bdmppy）Cl]（PF₆）（32）. These results may provide insightinto the varieties of coordination spheres of the metal sites in MT when N-donor ligandsor other metal ions are present.5. Reaction of MeHgI with Ag2O in H₂O followed by addition of equimolarTabHPF₆in MeCN gave rise to approximately linear coordination geometry complex [MeHg（Tab）]PF₆（33）. In order to explore the mechanism of the Hg-C cleavage, wecarried out the reactions of33with some donor ligands, such as I-, SCN-, Tab,4,6-Me2pymSH, and resulted in the formation of another five MeHg/Tab compounds[MeHg（Tab）]I·0.5H₂O （34）,[MeHg（Tab）]SCN （35）,[MeHg（Tab）₂]（PF₆）（36）,[Hg（Tab）₂（SCN）₂]（37）,[Hg（Tab）₄]3（PF₆）₆·MeOH·2MeCN （38）. The results suggestedthat cleavage of the Hg-C bond in the methylmercury complex could be promoted byincreasing the coordination number of its Hg（II） center.