Structure and properties of two new heteroleptic bismuth(III) dithiocabamates of the general composition Bi(S2CNH2)2X (X = Cl, SCN)

The title compounds were prepared by precipitation from acidic solutions of the reactants in acetone/water. Bi(S2CNH2)2Cl (1) crystallizes in the non-centrosymmetric trigonal space group P32 with a = 8.6121(3) and c = 11.1554(4) Å, Z = 3; Bi(S2NH2)2SCN (2) in P21/c (monoclinic) with a = 5.5600(2), b = 14.3679(5), c = 12.8665(4) Å, and β = 90.37(3)°. In the crystal structure of 1 Bi3+ is in a sevenfold coordination of two bidentate and one monodentate S2CHNH2 − anions with an asymmetric coordination pattern of five Bi–S and two Bi–Cl− bonds. The linkage of these polyhedra via common Cl–S edges leads to a 1D polymeric structure with undulated chains propagating in the direction [001]. These chains are linked by strong and medium strong hydrogen bonds forming the 3D crystal structure. In the crystal structure of 2 the Bi3+ cation is in an eightfold coordination. The polyhedron can be described as a significantly distorted tetragonal anti-prism, capped by an additional S atom. Two of these prisms share a common quadrilateral face to form a “prism-double” (Bi2S10N2). These building units are linked by common edges, and the resulting 1D infinite angulated chains propagate along [100]. By contrast to organo-dithiocarbamate compounds, where C–H···X bridges are dominant, the interchain connections in the crystal structures of 1 and 2 are formed exclusively via N–H···S, N–H···Cl, and N–H···N interactions, generating the 3D networks. A significant eccentricity of the Bi3+ cation in the crystal structures of both complexes is observed. Both compounds emit light in the orange range of the electromagnetic spectrum.

Exploring the Coordination Potential of Monodentate and Bidentate Bicyclic Guanidine Ligands

<p>This thesis reports investigations of the interaction of arene-bicyclic guanidine ligands, using the 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) guandine (Figure i) as a foundation, with a variety of metal centres. Beginning with 1-benzyl-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (Ph(CH2hpp)), attempts were made to coordinate this ligand to group 1 metal N{SiMe3}2- salts, which resulted in a novel NaN{SiMe3}2 crystal structure. Ligands comprised of a phenyl group with multiple hpp units in varying substitution patterns were also synthesised and reacted with group 1 metal N{SiMe3}2- salts to investigate the possibility of bidentate and tridentate arene-hpp coordination. This resulted in the synthesis of two novel compounds containing KN{SiMe3}2. Both sigma and pi-interactions with potassium were observed in the crystal structure of one of these compounds. NMR data that support analogous coordination to lithium and sodium analogues were also obtained. The ligands with multiple hpp units were introduced to highly reactive main group antinomy and bismuth species in an attempt to achieve a coordination with increased hapticity of the pi-interaction. A novel antimony structure was obtained with asymmetric coordination of an arene-hpp ligand in which an intramolecular C-H activation was achieved. An N-phosphino guaninde was synthesised and employed in this research due its potential to coordinate through both its available nitrogen and phosphorus atoms. This ligand was reacted with a variety of metal centres which revealed information about the strength of the N-P bond in the ligand. Two novel crystal structures were obtained which both contained novel group 1 clusters with coordinating hpp units. Finally, attempts were made to coordinate Ph(CH2hpp) to transition metal halides and N{SiMe3}2- salts. These attempts resulted in one novel crystal structure.</p>

Exploring the Coordination Potential of Monodentate and Bidentate Bicyclic Guanidine Ligands

<p>This thesis reports investigations of the interaction of arene-bicyclic guanidine ligands, using the 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) guandine (Figure i) as a foundation, with a variety of metal centres. Beginning with 1-benzyl-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (Ph(CH2hpp)), attempts were made to coordinate this ligand to group 1 metal N{SiMe3}2- salts, which resulted in a novel NaN{SiMe3}2 crystal structure. Ligands comprised of a phenyl group with multiple hpp units in varying substitution patterns were also synthesised and reacted with group 1 metal N{SiMe3}2- salts to investigate the possibility of bidentate and tridentate arene-hpp coordination. This resulted in the synthesis of two novel compounds containing KN{SiMe3}2. Both sigma and pi-interactions with potassium were observed in the crystal structure of one of these compounds. NMR data that support analogous coordination to lithium and sodium analogues were also obtained. The ligands with multiple hpp units were introduced to highly reactive main group antinomy and bismuth species in an attempt to achieve a coordination with increased hapticity of the pi-interaction. A novel antimony structure was obtained with asymmetric coordination of an arene-hpp ligand in which an intramolecular C-H activation was achieved. An N-phosphino guaninde was synthesised and employed in this research due its potential to coordinate through both its available nitrogen and phosphorus atoms. This ligand was reacted with a variety of metal centres which revealed information about the strength of the N-P bond in the ligand. Two novel crystal structures were obtained which both contained novel group 1 clusters with coordinating hpp units. Finally, attempts were made to coordinate Ph(CH2hpp) to transition metal halides and N{SiMe3}2- salts. These attempts resulted in one novel crystal structure.</p>

Voluntary redistribution mechanism in asymmetric coordination games

An inequality game is an asymmetric 2 × 2 coordination game in which player 1 earns a substantially higher payoff than player 2 except in the inefficient Nash equilibrium (NE). The two players may have either common or conflicting interests over the two NE. This paper studies a redistribution scheme which allows the players to voluntarily transfer their payoffs after the play of an inequality game. We find that the redistribution scheme induces positive transfer from player 1 to player 2 in both common- and conflicting- interest games, and is particularly effective in increasing efficient coordination and reducing coordination failures in conflicting-interest games. We explain these findings by considering reciprocity by player 1 in response to the sacrifice made by player 2 in achieving efficient coordination in conflicting-interest games.

Generalising Asymmetric Coordination with Resumptive Pronoun: A Syntactic Analysis of Certain Dislocations in Biblical Hebrew

This study clearly distinguishes Biblical Hebrew topicalisation (fronting) from the hanging topic construction (extraposition) within the framework of the Minimalist Program. Topicalisation involves the movement of some constituent into [spec,TopP] resulting in a gap. In contrast, the hanging topic is not moved but rather base-generated in [spec,&P]. Thus, extraposition is simply a special case of asymmetric coordination. In addition, this study explains how and why these distinct constructions are easily and generally confused. On the one hand, verb movement into the left periphery may render the relative position of constituents opaque. On the other hand, and more importantly, Biblical Hebrew is a robust pro-drop language. Consequently, there may be some ambiguity between the gap resulting from clause-internal topicalisation and the apparent gap of a null subject pronoun resuming a clause-external hanging topic.