Fused Supracyclopentadienyl Ligand Precursors. Synthesis, Structure, and Some Reactions of 1,3-Diphenylcyclopenta[l]phenanthrene-2-one, 1,2,3-Triphenylcyclopenta[l]phenanthrene-2-ol, 1-Chloro-1,2,3-triphenylcyclopenta[l]phenanthrene, 1-Bromo-1,2,3-triphenylcyclopenta[l]phenanthrene, and 1,2,3-Triphenyl-1H-cyclopenta[l]phenanthrene

The photochemical reaction of 1,3-diphenylcyclopenta[l]phenanthrene-2-one 5 (phencyclone) with oxygen in acetone leads to the formation of 1,2,3-trihydro-1,2,3-triphenylcyclo-penta[l]phenanthrene 7 (9,10-dibenzoylphenanthrene) along with a trace of the lactone 1,4-diphenylcyclo-3-pyran[l]phenanthrene-2-one 8. An independent synthesis of 8 was achieved by the reaction of 5 with FeCl3 in CHCl3. The treatment of 5 with phenyllithium yields 1,2,3-triphenylcyclopenta[l]phenanthrene-2-ol 9-OH in good yield. Subsequent reaction of 9-OH with SOCl2 or SOBr2 in pyridine leads to the formation of the halo-analogues 1-chloro-1,2,3-triphenylcyclopenta[l]phenanthrene 9-Cl and 1-bromo-1,2,3-triphenylcyclopenta[l]phenanthrene 9-Br, respectively. Treatment of 9-OH with HBr in acetic acid affords the rearranged product 1,1,3-triphenylcyclopenta[l]phenanthrene-2-one 10 with a trace of 9-Br. Treatment of 9-Cl or 9-Br with zinc in acetic acid affords 1,2,3-tri-phenyl-1H-cyclopenta[l]phenanthrene 9-H. 9,10-Phenanthrenediylbis(phenyl)methanone 7 is formed in good yield upon treatment of 9-OH with HI in acetic acid followed by heating with H2PO4. Compounds 7, 8, 9-Cl, 9-Br, and 10 have been structurally characterized using X-ray crystallography.

Complexity of coordinative bonding in thallium(I) anthranilates and salicylates

An inventory of the structural chemistry of thallium(I) shows many unexpected, almost random coordination numbers and coordination geometries that appear erratic and inconsistent. This nonstandard behavior is often ascribed to the specific lone-pair characteristics originating from relativistic effects. To provide data on a set of closely related compounds from which simple general rules of coordinative bonding at Tl(+) can be established, three thallium(I) anthranilates and three thallium(I) salicylates have been prepared from Tl(2)CO(3) and the corresponding 2-amino- and 2-hydroxy-benzoic acids and crystallized from aqueous solutions. All six compounds, the simple anthranilate (1) and salicylate (4) and the 3- and 4-methyl-substituted homologues (2, 3 and 5, 6) show different structures with large variations in the coordination motif. The coordination by oxygen in a geometry which covers less than a coordination hemisphere is the only common feature, complemented (only in 1) by a nitrogen coordination and by eta(6)-coordination of one (in 1, 2, 3, 6) or two phenyl rings (in 4). Tl-Tl contacts for which "thallophilic" bonding between closed shell metal atoms could be invoked, are generally very long (close to 4.0 A) or even well beyond the limit of standard van der Waals contacts. Hydrogen bonding is only obvious for the internal contacts of the amino- or hydroxy-benzoate ligands and does not contribute significantly to the assembly of the supramolecular structure which is dominated by oxygen bridges between thallium atoms. With the exception of 5, the formula units Tl[O(2)C(2-R)(3-R')(4-R'')C(6)H(2)] are generally aggregated into dimers of various configurations depending on the relative orientation of the edge-sharing four-membered rings, and these dimers are further linked into strings or columns establishing N-Tl or Tl-O contacts and arene coordination. The drastic changes induced in the structures upon only small variations such as methyl substitution in 3- or 4-position of the ligand suggest that thallium(I) coordination is generally restricted to one hemisphere of nearest neighbors, but is extremely flexible in this realm. The open hemisphere may be partially capped by arene coordination (which is weak at a distance of ca. 3.1 A to the centroid of the ring) or feature very weak thallophilic contacts.

X-ray crystal structure of (eta(5)-pentaphenylcyclopentadienyl)[1-(eta(5/6)-phenyl)-2,3,4,5-tetraphenylcyclopentadienyl]iron(II), [Fe(eta(5)-C(5)Ph(5))[(eta(5/6)-C(6)H(5))C(5)Ph(4)]], a linkage isomer of decaphenylferrocene

Very dark blue prismatic crystals of [Fe(eta(5)-C(5)Ph(5))[(eta(5/6)-C(6)H(5))(C(5)Ph(4))]], the linkage isomer of decaphenylferrocene, were grown from (3:1 v/v) hexane/ethyl acetate and characterized by single-crystal X-ray diffraction (space group P2(1)/n, R1(F) 0.0404). The iron atom is coordinated to two C(5)Ph(5) ligands: one with an eta(5)-C(5)-configuration and the other with a coordinated arene configuration. The phenyl groups of the (eta(5)-C(5)Ph(5)) ligand are oriented in a "paddle-wheel" arrangement about the C(5) ring, with which four of them make an average angle of approximately 53 degrees, the other, an angle of approximately 42 degrees. The coordinated C(6)H(5) ring of the other ligand is inclined at only approximately 5 degrees to the uncoordinated C(5) ring, with which three of the other four phenyl rings make an average angle of approximately 64 degrees, and the other (opposite the coordinated arene ring), an angle of 38 degrees.