Electrochemical, spectroscopic, and structural evidence for the mild hydrolysis of tetracyanoethylene, TCNE, to form the 2,3,3-tricyanoacrylamidate ligand: isolation of an unexpected quadruply-bonded polymeric material [Mo2(O2CCMe3)3((NC)2CC(CN)CONH)]infinity

Under strictly anhydrous conditions, no reaction occurs between Mo(2)(O(2)CCMe(3))(4) and tetracyanoethylene, TCNE, at room temperature, but after addition of 1 equiv of water, a reaction proceeds to form [Mo(2)(O(2)CCMe(3))(3)((NC)(2)CC(CN)CONH)], 1. The compound contains a quadruple-bonded Mo(2) unit and the 2,3,3-tricyanoacrylamidate anion as a ligand (TC3A), a very unusual hydrolyzed form of TCNE. Two different solid-state structures were obtained after crystallization of 1. Crystals obtained from CH(2)Cl(2) consist of a two-dimensional network, and crystals grown from a C(6)H(6) solution form a 1-D chain motif. In both cases, the TC3A ligand acts as a polydentate ligand involving a bidentate OCN bridging unit and two CN groups. The electrochemical and spectroscopic (IR, UV/vis/near-IR, NMR, EPR) properties of 1 support the formulation in solution as a discrete 1:1 complex of the TC3A donor ligand and a Mo(2) unit with no charge transfer. The coordinated TC3A ligand exhibits redox properties similar to those of free TCNE.     

Synthesis and crystal structure of two new discrete, neutral complexes of manganese and zinc using a rigid organic clip

Two discrete neutral dimanganese(II) and tetrazinc(II) complexes were synthesized from a rigid organic clip and the corresponding metal acetates. The compounds were characterized by elemental analysis and single crystal X-ray diffraction study. The manganese species is a dinuclear discrete product with two disordered acetates bridging two manganese centers, while the zinc one consists of two octahedral and two tetrahedral Zn(II) centers with both bridging acetates and triply micro(3)-hydroxides. Variable temperature magnetic measurement reveals the existence of weak antiferromagnetic interaction (J = -1.6 cm(-)(1); H = -2JS(1).S(2)) within the manganese complex.     

Flexible bidentate pyridine and chiral ligands in the self-assembly of supramolecular 3-D cages

Discrete, nanoscopic 3-D cages are prepared in high yield via coordination-driven self-assembly from a variety of building blocks, including bidentate 3-substituted pyridines, chiral, and silicon-based tripods. All are characterized by NMR ((31)P, (1)H) and electrospray ionization mass spectrometry.     

Convenient syntheses of fluorous phenols of the formula HOC6H5−n((CH2)3(CF2)7CF3)n (n=1, 2) and the corresponding triarylphosphites

The aldehydic benzyl ethers PhCH₂OC₆H₄CHO (2; a/b = para/meta series) are readily available from the corresponding phenols and react with Wittig reagents derived from [Ph₃PCH₂CH₂R_f8]⁺I⁻ (R_f8=(CF₂)₇CF₃) to give PhCH₂OC₆H₄CHCHCH₂R_f8 (86-93%, Z major). Reactions with H₂ over Pd/C give the fluorous phenols HOC₆H₄(CH₂)₃R_f8(4a,b; 87-91%). Condensations with PCl₃ and NEt₃ (3.0:1.0:3.3 mol ratio) give the fluorous phosphites P[OC₆H₄(CH₂)₃R_f8]₃(5a,b; 92-94%), but traces of 4a,b are difficult to remove. The phthalate-based benzyl ethers PhCH₂OC₆H₃(COOR)₂ (7; ,5/3,4 OC₆H₃-3,n-(R)₂ series) are easily accessed and reduced with LiAlH₄ to the diols PhCH₂OC₆H₃(CH₂OH)₂(8c,d; 89-90%). Diol 8c and the Dess-Martin periodinane react to give the dialdehyde PhCH₂OC₆H₃(CHO)₂ (9c; 95%). This is elaborated by a sequence analogous to 2→4→5 to the fluorous phenol HOC₆H₃((CH₂)₃R_f8)₂ (11c; 97%/96%, two steps) and phosphite P[OC₆H₃((CH₂)₃R_f8)₂]₃ (12c, 92%), from which traces of 11c are difficult to remove. Diol 8d can be similarly elaborated to 11d, but the dialdehyde 9d is labile and the combined yield of the Dess-Martin/Wittig steps is 32%. The CF₃C₆F₁₁/toluene partition coefficients of 11c,d, and 12c (two pony tails; 70:30, 72:28, 92:8) are much higher than those of 4a and b (one pony tail; 12:88, 14:86).     

Functionalized hydrophobic and hydrophilic self-assembled supramolecular rectangles

The synthesis of six new, functionalized 180 degrees pyridyl donor ligands and their coordination-driven self-assembly into supramolecular rectangles is reported. Three of the new donors have been functionalized with hydrophobic straight chain alkane units (C6, C12, and C18) while the remaining three have been functionalized with derivatized di-, tetra-, and hexaethylene glycol hydrophilic units (DEG, TEG, and HEG, respectively). The resulting self-assembled hydrophobic and hydrophilic supramolecular rectangles have been fully characterized by multinuclear NMR and electrospray ionization mass spectrometry. Molecular force field modeling suggests that the functionalized rectangles range in size from roughly 3.0 x 2.9 to 3.0 x 6.0 nm2 in size.     

Synthesis of a new family of hexakisferrocenyl hexagons and their electrochemical behavior

The design and synthesis of two new hexakisferrocenyl hexagons has been achieved via coordination-driven self-assembly wherein the size and relative distribution of six ferrocene moieties has been precisely controlled. Insight into the structure and electronic properties of these supramolecules was obtained through electrochemical studies.