S. A. Shah

A transition metal complex as a ligand in the chemistry of group (IV) elements

Abstract Heterobimetallic complexes of the type [Cu(TETA)Cl 2 MCl 2 ] (M = Si, Ge, Sn, Ti and Zr; TETA = tiethylene tetramine) have been synthesized and characterized by elemental analyses, ESR, electronic and IR spectra and conductivity measurements. The complex [Cu(TETA)Cl 2 SnPh 2 ] has also been prepared. The results indicate that [Cu(TETA)]Cl 2 is square planar and ionic in nature, while its bimetallic complexes, [Cu(TETA)Cl 2 MCl 2 ] and [Cu(TETA)Cl 2 SnPh 2 ], are covalent with an octahedral environment around the copper(II) ion.

Synthesis, Characterization and Reactivity of New Hetero-Bimetallic Complexes

Abstract Heterobimetallic complexes of the type [Cu(TETA) C12MCl2] where M = Si, Ge, Sn, Ti or Zr, TETA-H2 = (triethylene tetramine) have been synthesized and characterized by elemental analysis, EPR spectra, electronic spectra, IR spectra, far-IR spectra and conductivity measurements. The complex [Cu(TETA)Cl2 SnPh2] has also been prepared. The results indicate that the compound [Cu(TETA-H2)]Cl2 is square planar and ionic in nature, while its bimetallic complexes, [Cu(TETA)Cl MCl2] and [Cu(TETA)Cl2SnPh2], have an octahedral environment around the Cu(II) ion. Another series of compounds of the type [Cu(TETA)C12M(TMDTC)2] has been prepared by the direct interaction of [Cu(TETA)Cl MCl2] with tetramethylenedithiocarbamate (TMDTC) in a 1:2 ratio in methanol. In these complexes, an octahedral stereochemistry around the Group IV metal has been observed in which the TMDTC acts as a bidentate ligand.

Group IV Metal Complexes of the Dithiocarbamate Ligahd Derived from Propanediamine

Abstract Fropanediamine dithiocarbamate and its metal complexes with MCl4. (Si = M Ge, Sn, Ti, and Zr) and Ph2-SnCl2 have been synthesized and characterized. The results indicate that MCI4. reacts in a 1, 4 (metal : dithiocarbamate) ratio yielding an octahedral compound with two symmetrically and two unsym-metrically bound dithiocarbamato groups while Ph2SnCl2 reacts in a 1: 1 ratio leading to the formation of a stable five-coordinate complex with the phenyl groups occupying the equatorial positions.

A route leading to a stable MHB unit (M = Si, Ge, Sn). The bidentate and tridentate behaviour of tetrahydroborate

Abstract The complex [MLCl 2 ] [M = Si, Ge and Sn, L = NN′-ethylene bis-(salicylideneiminate) reacts with KBH 4 in THF to give [ML(BH 4 ) 2 ]. The results indicate that the BH − 4 ion behaves as a bidentate ligand and the central metal atom possesses eight-coordination. The conductivity measurements reveal their covalent nature. Another series of compounds of the types [R 2 Sn(BH 4 ) 2 ] (R = Me, Bu and Ph) and [R 3 Sn(BH 4 ] (R = Bu and Ph) have been synthesized by the direct interaction of R 2 SnCl 2 and R 3 SnCl with excess KBH 4 in THF, respectively. In this case it is found that the tetrahydroborate group acts as a tridentate ligand implying eight- and six-coordination of the tin atom, respectively. The molar conductance value ascertains their non-electrolytic character.

The tridentate bonding mode of tetrahydroborate towards germanium and tin

Abstract The interaction of germanium and tin tetrachlorides with an excess of KBH4 in dry THF results in the formation of novel compounds of the type M(BH4)4 (M = Ge and Sn). The results indicate that the compounds are non-electrolytes and the BH−4 anion links covalently to the group IV metal atom in a tridentate manner.

Formation of Sn(II)→M(IV) Metal Donor-Acceptor Bonds (M = Si, Gc, Sn, Ti and Zr)

Abstract Novel compounds of the type Sn2MCl8(Py)2, Sn3Ph2Cl6(Py)2 and Sn3Ph3Cl5Py)2 have been synthesized and characterized. They have been found to be non-electrolytes in DMSO. The central metal atom extends its coordination number from four to six yielding a trinuclear compound containing Sn(II) → Group(IV) metal bonds. The Mossbauer spectra of the complexes suggest that the 5s electron density remains slightly localized at the tin site.

Transition Metal Complexes of a New 12-Membered Tetraaza Macrocycle

Abstract The direct reaction of triethylenetetramine and diethyl oxalate in DMF in a 1:1 ratio results in the formation of the 12-membered tetraazamacrocycle triethylenetetramine oxamide (L). A condensation reaction of triethylenetetramine and diethyl oxalate in the presence of divalent hydrated transition metal chlorides (Mn2+, Co2+, Ni2+, and Cu2+) and ZnCl2 in absolute methanol in a similar ratio (1:1:1) yields ionic 12-membered macrocyclic complexes. The results show that two water molecules are bound to the central metal ion (Mn2+, Co2+, Ni2+ and Cu2+) resulting in an octahedral environment while zinc maintains a tetrahedral geometry for being free from water. The i.r. spectral bands show that the two C=O groups of the oxalato species do not participate in coordination. The slight decrease in (C=O) suggests bonding of the nitrogen of the amide group to the metal ion. The complexes decompose on dissolution in DMSO. Referee I: Z. Kovacz Referee II: K. M. Doxsee

Tunable Interaction of NN′-Ethylenebis(Salicylideneiminato) Copper(II) with Group IV Metal Tetrachlorides

Abstract New heterobimetallic chelates [CuLMCl4] [M = Si, Ge, Sn, Ti and Zr; L = NN′-ethylenebis(salicylideneiminate)] prepared by treating CuL with Group IV metal tetrachlorides in a 1:1 ratio were characterized by e. s. r., electronic and i. r. spectroscopy, elemental analysis and conductivity measurements. The e. s. r. spectral g-values indicate square planar environments for copper(II) in both CuL and [CuLMCl4]. Conductivity measurements show that the heterobimetallic chelates are non-electrolytes. The phenolic C-O stretching frequency shifts to higher frequencies in the i. r. spectra of auducts suggesting that a coordinate bond is formed between oxygen of CuL and the Group IV metal.

Synthesis and Characterization of Pyrrolidine-N-carbodithioate and Its Group IV Metal Complexes

Abstract Pyrrolidine-N-carbodithioate and its complexes of the type M(S2CNC4H8)4, MCl2(S2CNC4H8)2 and Sn(S2CNC4H8)2Bu2 (where M = Si, Ge, Sn, Ti or Zr and Bu = butyl) have been synthesized and characterized. The results indicate that M(S2CNC4H8)4 complexes have octahedral geometry with two symmetrically and two unsymmetrically bound dithiocarbamate moieties while M(S2CNC4H8)2Cl2 and Sn(S2CNC4H8)2Bu2 have octahedral geometry with two bidentate dithiocarbamates.

A Stable Eight-Membered Ring1 Interaction of Methylenebis-(Piperidinedithiocarbamate) with Group IV Metal Tetra-Chlorides and Organot in Chlorides

Abstract The synthesis of new compounds of the type MCI4 L, R2SnCl2L, R3SnClL and R4SnL (M = sl, Ge, Sn, Tl and zr; L = methylenebis (piperidinedithiocarbamate) and R = phenyl) are reported. The results indicate the coordination of the two terminal sulphur atoms (C=S) to the metal results in the formation of eight-membered ring complexes. An octahedral geometry has been proposed for the Group IV metal in which the chlorines are adopting cis-configuration.