Browsing by Subject "organometallic"
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Item Preparation and Characterization of Cyanide-Bridged Molecular Clusters and Extended Networks Using the Building-Block Approach(2011-02-22) Karadas, FerdiThe cyanide ligand has frequently been used to prepare clusters with novel magnetic properties due to its ability to provide an efficient pathway for superexchange between metal centers that are bound in an end-to-end fashion. One of the common synthetic approaches in this chemistry is to design suitable cyanide containing precursors and then to react such building blocks with metal complexes consisting of accessible sites. The triphos ligand (triphos: 1,1,1-tris(diphenylphosphinomethyl)ethane) has been employed in this vein to prepare metal complexes, one of which is a five coordinate paramagnetic complex (S = 1/2) with a square pyramidal metal center, [CoII(triphos)(CN)2]. A family of molecular squares, [{MIICl2}2{CoII(triphos)(CN)2}2] (M= Mn (2), Fe (3), Co (4), Ni (5), and Zn (6)), has been synthesized by the reaction of CoII(triphos)(CN)2 and MCl2 (M= Mn, Co, Ni, Zn) or Fe4Cl8(THF)6 in CH2Cl2/EtOH mixture. A series of cyanide-bridged trinuclear complexes, {[Co(triphos)(CN)2]2 [M(MeOH)4]}(ClO4)2 ( M = Mn (7), Fe (8), Co (9), and Ni (10)) and tetranuclear complexes, {[Co(triphos)(CN)2]2[M(MeOH)4]2}(ClO4)4 ([Co2M2] M = Mn (11) and Ni (12)) have been synthesized in a similar fashion by the reaction of CoII(triphos)(CN)2 and M(ClO4)2.6H2O (M= Mn, Fe, Co, Ni) in methanol. The trinuclear compounds (7-9), and tetranuclear complexes (2-6, 11, 12), are characterized by antiferromagnetic coupling between metal centers while magnetic behavior of 10 indicates the presence of ferromagnetic interactions between the paramagnetic metal centers. Interactions between magnetic orbitals of Co(II) and M(II) ions were also investigated by means of the density functional theoretical (DFT) calculations. Another triphos containing building block, [(triphos)Re(CN)3] anion (13), has been employed to prepare derivatives of a cubic SMM cluster with four octahedral Re(II) ions and four tetrahedral Mn(II) sites bridging through cyanide ligand. The reactions of Re(II) precursor with MnI2 and solvated Mn(II) ions resulting in derivatives of Re4Mn4 cube with different ligands attached to the Mn center other than the chloride atom were reported. Our efforts on linking these cubes using organo cyanide ligands such as dicyanamide (dca) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) to form extended networks were also discussed.Item Studies of Platinum Polyynyl Complexes: Elaboration of Novel "Click" Cycloadducts and Fluorous and Polygon Based Platinum Polyyndiyl Systems(2012-11-13) Clough, Melissa Catherine 1985-The major directions of this dissertation involve (1) the syntheses and characterization of molecular polygons incorporating sp1hybridized carbon linkers and L2Pt corners (L2 = cis-1,3-diphosphine), (2) the development of protected carbon chain complexes featuring fluorous phosphine ligands and (3) click reactions of metal terminal polyynyl complexes and further metallations of the resulting triazole rings. A brief overview is provided in Chapter I. Chapter II details the syntheses of molecular squares containing bidendate diphosphine ligands of the formula R2C(CH2PPh2)2 where R = Me, Et, n-Bu, n-Dec, Bn, and p-tolCH2 (general designation dppp*), in which the R2 groups are intended to circumvent the solubility issues encountered by others. Their syntheses involve double substitutions of the dimesylate compounds R2C(CH2OMs)2 using KPPh2. Building blocks of the formulae (dppp*)PtCl2 and (dppp*)Pt((C?C)2H)2 are synthesized and characterized, including one crystal structure of the latter. The target complexes are accessed by reactions of (dppp*)PtCl2 with (dppp*)Pt((C?C)2H)2 under Sonogashira type conditions. Six new squares of the formula [(R2C(CH2PPh2)2)Pt(C?C)2]4 are characterized including two crystal structures. Further topics include approaches to higher homologues and cyclocarbon synthesis. Chapter III focuses on carbon chain complexes bearing fluorous phosphine ligands of the formula P((CH2)mRfn)3 (Rfn = (CF2)n-1CF3; m/n = 2/8, 3/8, and 3/10). Precursors of the formula trans-(C6F5)((Rfn(CH2)m)3P)2PtCl are synthesized and characterized, including one crystal structure, which reveals phase separation of the fluorous and non-fluorous domains. Reactions with butadiyne give trans-(C6F5)((Rfn(CH2)m)3P)2Pt(C?C)2H. Oxidative homocouplings afford the target complexes trans,trans-(C6F5)((Rfn(CH2)m)3P)2Pt(C?C)4(C6F5)(P((CH2)mRfn)3)2Pt. Cyclic voltammetry indicates irreversible oxidations of the title compounds, in contrast to partially reversible oxidations of non-fluorous analogues. Chapter IV focuses on multimetallic complexes achieved by click reactions in metal coordination spheres. The copper catalyzed click reaction between trans-(C6F5)(p-tol3P)2Pt(C?C)2H (1) and (?5-C5H4N3)Re(CO)3 affords the bimetallic 1,2,3-triazole trans-C6F5)(p1tol3P)2PtC?CC=CHN((?51C5H4)Re(CO)3)N=N. Further reactions with Re(CO)5OTf and Re(CO)5Br give trimetallated adducts, which represent the first species of this type. An alternative route to a trimetallic complex involves the twofold cycloaddition of the diazide (?5-C5H4N3)2Fe and 1, giving (?5-C5H4NN=N-C(trans-(C?C)Pt(Pp-tol3)2(C6F5)=CH)2Fe. The crystal structures of the di and trimetallic complexes are compared, but attempts to achieve a fourth metallation involving the =CH groups are unsuccessful. However, when the triazolium salt [trans-(C6F5)(p-tol3P)2PtC?CC=CHN(CH2C6H5)N=N(Me)]+ I? is treated with Ag2O and [Rh(COD)Cl]2, a =CRh adduct is obtained. The success of =CH metallation is correlated to the 1H NMR chemical shift, indicative of an electronic effect.