Xanthate Anions as Salts of bis (Cyclopentadienyl) titanium(IV) Chelates

Abstract

B i s (cyclopentadienyl) t i t a n i u m d i c h l o r ide, when created w i t h 2.3-dihydroxypyridine and 2-a1nino-3-hydroxypyridine i n aqueous medium, forms s o l u b l e i o n i c d e r i v a t i v e s of t h e type [ ( Q J )~T~L ] +Cl-(HL = 2, 3-dihydroxypyridine or 2-amino-3-hydroxy p y r i d i n e ) . These two complexes r e a c t with xanthate anions i n aqueous s o l u t i o n giving i o n i c complexes of t h e type [(Cp)2TLl+ROCS2-, where R= M e , E t o r p r . The l a t t e r complexes have been c h a r a c t e r i s e d b y elemental analyses, conductance measurements, e l e c t r o n i c , I R and PMR s p e c t r a l s t u d i e s .

Synthesis and Characterization of Some Transition Metal Complexes of 2-Amino-3-hydroxypyridine and its Application in Corrosion Inhibition

“…The protons of the hydroxy and amino groups appear as singlets at 9.47 (broad) and 5.41 ppm, respectively. For the complexes, the resonance arising from the hydroxy proton disappears, whereas that arising from the amino protons is shifted to lower ®eld indicating chelation of the ligand via the deprotonated hydroxy oxygen atom and the amino nitrogen atom to the metal ion [4]. Also, the resonances arising from H 4 , H 5 , and H 6 are shifted to higher ®eld, probably due to electron withdrawal by the metal causing decreased electronic density in the pyridine ring [22].…”

“…The complexes M(ahp) 2 (M Co, Cu, Pd) show a new band near 500 cm À1 in both the IR and Raman spectra which may arise from v(M-O) stretches [18,19]. New bands can be been found near 470 cm À1 in the IR and Raman spectra of all reported complexes, probably arising from v(M-N) modes [4,5,20,21].…”

“…The strong band at 1600 cm À1 assigned to (NH 2 ) in the ligand is shifted near 1620 cm À1 in the complexes [5]. In the spectra of ligand and complexes, the bands observed near 1290 and 1210 cm À1 probably arise from v(C-N) and v(C-O) stretching vibrations, respectively [4,5,13].…”

“…The stretching vibration of the free ligand (v(OH), 3250 cm À1 ) is not observed in the complexes, suggesting deprotonation of the hydroxy group and formation of M-O bonds [4,13]. Bands near 3440 and 3310 cm À1 in the free ligand are assigned to v asym (NH 2 ) and v sym (NH 2 ), respectively; these bands are shifted to lower wave numbers in the complexes due to the coordination of the amino group Five-membered ring formed by chelation of 2-amino-3-hydroxypyridine with a metal ion nitrogen atom to the metal ion [4]. The strong band at 1600 cm À1 assigned to (NH 2 ) in the ligand is shifted near 1620 cm À1 in the complexes [5].…”

“…2-Amino-3-hydroxypyridine is biologically important in the preparation of clinical antiin¯ammatory analgesics [3]. There are only few known transition metal complexes [4,5] or crystal structures [6] of 2-amino-3-hydroxypyridine: [Cp 2 Zr(ahp)] [4], [RuCl 2 (AsPh 3 ) 2 (ahp)] [5], and [(abhp) 2 Cu 2 Br 6 Á 2H 2 O] ( [6]; abhp 2-amino-4-bromo-3-hydroxypyridine). Also, the complexes of 2-amino-3-hydroxypyridinesalicylaldehyde Schiff base with M(II) (Co, Ni, Cu, Pt) and VO 2 have been reported [7].…”