Wesley H. Monillas

Heteroleptic iminopyrrolidinates of aluminium

A series of iminopyrrolidine (ip) compounds were synthesized with excellent yields as potential ligands for novel organometallic precursors for atomic layer deposition. The idea behind these ligands was that carbodiimide (CDI) deinsertion would not occur as the quaternary carbon was tethered to one chelate nitrogen. To our advantage a melting point trend was evident within the ip ligands and reflected in the family of heteroleptic aluminium species when the ip ligands were reacted with TMA or TEA. The alkane elimination reaction occurred at room temperature yielding clean products with high yields. Crystal structures were collected for compounds 7 [ipipAlMe(2)], 12 [tbipAlMe(2)], and 14 [sbipAlEt(2)] demonstrating that the heteroleptic aluminium species were dimers. This was also evident in the mass spectra collected for each compound as the parent peak was that of the dimer minus a methyl. Thermolysis studies were carried out on all the ipAlMe(2) species to observe the decomposition at an isotherm over several days. The decay of the methyl peak was monitored as a ratio against TMS within the solution and was shown to be a first order decomposition. From these studies it was clear that nbip (9), iso-bip (10), and tbip (12) were the most stable complexes with half-lives of 24.8, 9.00, and 10.3 days, respectively.

Tris(triazolyl)borate ligands of intermediate steric bulk for the synthesis of biomimetic structures with hydrogen bonding and solubility in hydrophilic solvents

Tris(triazolyl)borate ligands (Ttz) of intermediate steric bulk were synthesized to investigate their potential for hydrogen bonding and improved solubility in hydrophilic solvents as applied to biomimetic chemistry. The crystal structure of 3-phenyl-5-methyl-1,2,4-triazole (Htz(Ph,Me)) revealed hydrogen bonding and pi stacking interactions. The new ligand salt, potassium tris(3-phenyl-5-methyl-1,2,4-triazolyl)borate (KTtz(Ph,Me)) was synthesized as the first example of a Ttz ligand of intermediate steric bulk. Metathesis between KTtz(Ph,Me) and NaCl followed by recrystallization produced [NaTtz(Ph,Me)].6CH3OH in which the geometry around the sodium is octahedral with an unusual N(3)O(3) donor set; this structure also shows that a hydrogen bonding network is formed by methanol molecules and triazole nitrogens. (Ttz(Ph,Me))ZnCl was synthesized and characterized crystallographically as [(Ttz(Ph,Me))ZnCl].0.5CH3OH in which the zinc is tetrahedral and the triazole rings are within hydrogen bonding distance of CH(3)OH. All of these new compounds are methanol soluble to varying degrees and Htz(Ph,Me) and KTtz(Ph,Me) are soluble in methanol/water mixtures.

Guanidinium 2-(myristoylsulfanyl)ethane­sulfonate

In the title compound, CH6N3 +·C16H31O4S2 − [systematic name: guanidinium 2-(tetradecanoylsulfanyl)ethanesulfonate], each 2-(myristoylthio)ethanesulfonate ion displays hydrogen bonding to three guanidinium counter-ions, which themselves display hydrogen bonding to two symmetry-related 2-(myristoylthio)ethanesulfonate ions. Thus each cation forms six N—H⋯O bonds to neighboring anions, thereby self-assembling an extended ladder-type network. The average hydrogen-bond donor–acceptor distance is 2.931 (5) Å. The alkyl chains form the rungs of a ladder with hydrogen-bonding interactions forming the side rails.