Florence L. Lee

Binuclear nickel(II) and cobalt(II) complexes of the novel binucleating ligand 3,6-bis(1′-pyrazolyl)pyridazine. Crystal and molecular structure and magnetism of bis[µ-3,6-bis(1′-pyrazolyl)pyridazine-N1(Ni1)N2′(Ni1)N2(Ni2)N2″(Ni2)]bis[diaquanickel(II)] tetrachloride dihydrate

Reaction of the ligand 3,6-bis(1′-pyrazolyl)pyridazine (ppd) with nickel(II) and cobalt(II) salts produces binuclear derivatives in which the two pseudo-octahedral metal centres are bound simultaneously between two adjacent ligands in a doubly bridged structure. The complex [Ni2(ppd)2(H2O)4]Cl4·2H2O (1) crystallizes in the triclinic space group P with a= 7.133 9(7), b= 10.331 0(6), c= 10.820 9(5)A, α= 85.503(4), β= 89.939(6), γ= 75.479(6)°, and Z= 1. Refinement based on 4 505 unique reflections gave R= 0.0353. The binuclear cation [Ni2(ppd)2(H2O)4]4+ is essentially planar with in-plane Ni–N distances of 2.1 30(2), 2.035(2), 2.059(2), and 2.1 21(2)A, axial Ni–O distances of 2.044(2) and 2.048(2)A, and N–Ni–N angles of 98.6(1), 77.8(1), 77.9(1), and 105.8(1)°. Variable-temperature magnetic susceptibility measurements on (1) indicate significant antiferromagnetic exchange between the nickel(II) centres with –J= 14.8 cm–1. Analogous cobalt(II) compounds are also produced and in one case, [Co2(ppd)2(OH)(H2O)2][ClO4]3·1.5H2O, a triply bridged structure is proposed involving an additional hydroxide bridge.

Baeyer–Villiger oxidation of 19-substituted steroidal ketones: structure of rearranged products involving participation of the 19-substituent

Baeyer–Villiger reactions of 19-hydroxy-4β,5-epoxy-5β-androstane-3,17-dione (2), 19-hydroxy-4α,5-epoxy-5α-androstane-3,17-dione (13), 17β,19-dihydroxy-5β-androstan-3-one (18), and 19-hydroxyandrost-4-ene-3,17-dione (1) are reported. When carbonyl functions are present at C-3 and C-17, Baeyer–Villiger rearrangement occurs preferentially at C-17. The rearrangement product obtained from the Δ4-3-ketone (1) was found to be 5β-formyl-5,19-dihydroxy-17-oxo-A-nor-3,5-seco-5β-androstane-3-carboxylic acid 5,19(R) lactol 3,5-lactone (27).

A new class of charge-transfer complexes

Ternary charge-transfer complexes of general formula RCl–MCln–(aromatic compound) have been synthesized where RCl is an oxychloride such as NOCl or POCL3 and MCln is a metal or metalloid chloride such as SbCL5 or BCl3.

Co-ordinated cyclo-tetraphosphosxane and cyclo-pentaphosphoxane; two configurations of the co-ordinated P4O4 ring

Thermal reactions of hexacarbonyl-chromium or -tungsten with bis(di-isopropylamino)phosphine oxide or photolysis of Mo(CO)6 with [Pri2NPO]3 afforded cis-M(CO)4[Pri2NPO]4, which contains both chair–boat and chair–chair forms of the co-ordinated P4O4 ring in solution as well as in the molecular structure; additional products of the chromium reactoin include the chromium cage complex, Cr2(CO)8[Pri2NPO]4, and Cr2(CO)7[Pri2NPO]5 which contains the novel cyclo-pentaphosphoxane P5O5 ring co-ordinated to one cis-Cr(CO)4 and one fac-Cr(CO)3 moiety.

A binuclear copper(II) complex with a large unoccupied rigid cavity derived from a non-macrocyclic polyhydroimidazole

The ligand 1,2,4,5-tetrakis(4,5-dihydroimidazol-2-yl)benzene (btim) forms a bis-chelating binuclear square-pyramidal copper(II) complex (Cu–Cu 7.610 A) with a large, unoccupied cavity and two parallel, eclipsed benzene rings separated by 3.93 A.

Synthesis, characterization, and exchange of complexes of (R)-N,N-dimethylaminoethylferrocene with SO2 and BF3

Sulfur dioxide and (R)-N,N-dimethylaminoethylferrocene (I) react with an enthalpy of formation of 21.5 ± 1 kcal mol−1 to give a complex with sulfur bonded to nitrogen. The SO2 exchanges between adduct molecules by a dissociation mechanism. BF3 reacts with the above amine to give an adduct and its partly hydrolyzed product, [(η5-C5H5)Fe(η5-C5H4—CH(CH3)N(CH3)2•BF(OH)2] (II). II crystallizes in the orthorhombic space group P212121 with a = 9.882(3), b = 10.625(5), and c = 13.988(13) A and z = 4. Rf = 0.102 and Rw = 0.104. Keywords: N,N-dimethylaminoethylferrocene complexes, X-ray structure, NMR exchange.