W. Gregory Jackson

The protonation and hydrogen transfer processes in alkene and alkyne derivatives of Os3 and H2Os3(CO)10

Abstract The complexes H 3 O s 3 (CO) 9 CMe, H 2 O s 3 (CO) 10 , H 2 O s 3 (CO) 9 L (L = PEt 3 , PPh 3 or AsPh 3 ), HO s 3 (CO) 10 CHC(H)Ph, and O s 3 (CO) 10 HC 2 Me undergo protonation in acid to yield [H 4 O s 3 (CO) 9 CMe] + and [H 4 O s 3 (CO) 10 ] 2+ , [H 3 O s 3 (CO) 9 L] + , [H 2 O s 3 (CO) 10 CHC(H)Ph] + and [HO s 3 (CO) 10 HC 2 Me] + , respectively. The structure of these ions and their hydrido-ligand transfer reactions are described.

Base Catalysed Hydrolysis of Aminecobalt(III) Complexes: From the Beginnings to the Present

This review examines the base catalysed hydrolysis process for cobalt(III) complexes. An overview of the reaction from its initial development to the present day is presented. The various mechanisms developed over the years, including S N 1CB, ion-pair, pseudo-base (covalent hydration), pseudo-aminate and E2 mechanisms, are presented and examined. Electronic, bulk steric, leaving group and solvent effects are covered. The question of and evidence for reduced coordination number intermediates is addressed in some detail. The review places an emphasis on current directions of research.

On the preference for the sym-fac isomer in the [Co(N, N'-bis(2-aminomethyl)amine)(2,2'-bipyridine)Cl]2+ system

Abstract The sym–fac isomer of [Co(bpma)(bipy)Cl]2+ is the only one synthesised for this system where, in principle, four exist (bpma=N,N′-bis(2-aminomethyl)amine, bipy=2,2′-bispyridine). This observation is supported by ab initio energy calculations which reveal this to be the most stable form, and the unsym–fac isomer the highest in energy. It is one of only two cobalt(III) complexes known that contain a single NH centre trans to Cl−. The structure is deduced from the 13C NMR spectrum and 2D NMR techniques and confirmed by the X-ray crystal structure determination. The agreement between the single crystal data and the calculated ab initio molecular parameters is excellent (within ±3%).

The structure of aqua-hydroxo double salts

Abstract The preparation and structure of two so-called aqua-hydroxo double salts of cobalt(III) are reported. X-ray structural analysis showed the compounds not to be double salts of two distinct mononuclear cations but to contain one binuclear cation in which the two equivalent cobalt atoms are bridged by a hydrogen oxide ligand (μ-H3O2). Compound 1, trans-{[Co(en)2NO2]2(H3O2)}(C1O4)3·2H2O forms monoclinic crystals, space group P21/n, with a = 12.098(2) A, b = 8.981(1) A, c = 14.415(2) A, β = 93.39(2)°, V = 1563(1) A3 and Z = 2. Compound 2, trans-{[Co(en)2NCS]2(H3O2)}(CF3SO3)3·H2O forms triclinic crystals, space group P 1 with a = 12.864(2) A, b = 14.429(2) A, c = 11. 177(1) A, α = 105.21(3)°, β = 100.33(2)°, γ = 65.96(2)°, V = 1822(1) A3 and Z = 2. The two structures were refined by least-squares methods to residuals of R = 0.077, Rw = 0.087 and R = 0.063, Rw = 0.069, respectively. In 1, the dimer resides on a crystallographic inversion center and the O⋯O separation in the H3O2 bridge is 2.412(9) A. In 2 there is no crystallographic symmetry imposed upon the dimer but the two CoO(H3O2) distances are identical within the experimental error. The O⋯O length in the H3O2 unit is 2.415(6) A.

The chemistry of [Co(triamine)(diamine)Cl]2+ complexes: the single crystal X-ray structures of five [Co(dien)(ibn)Cl]ZnCl4 isomers

Abstract Of the seven isomeric forms possible for [Co(dien)(ibn)Cl]2+ system, the structures of three mer- and two fac-isomers have been determined by single crystal X-ray diffraction. The structural work corroborates the detailed 2D NMR study reported elsewhere.

Simple syntheses of some isomeric trinuclear osmium carbonyl clusters containing a cycloosmahexadienone fragment

Abstract The reactions between acetylenes and H2 Os3 (CO)10 have given novel complexes of stoichiometry Os3 (CO)10 (RC2 R′)2.

Anionopentaaminecobalt(III) complexes with polyamine ligands 28. The crystal structures of [CoCl(tacn)(en)]ZnCl4, [CoCl(tacn)(ampy)]ZnCl4·H2O, unsym-[CoCl(N-Metacn)(en)]-ZnCl4·H2O, trans-(R,S)-[CoCl(2,2,3-tet)(NH3)]ZnCl4 and unsym-fac-[CoCl(bn)(dien)]ZnCl4

Abstract The structures of some [CoCl(N)5]ZnCl4·xH2O complexes have been determined by single crystal X-ray diffraction. Only one isomeric form is possible for each of [CoCl(tacn)(en)]ZnCl4 (monoclinic P2 1/c , a=8.143(2), b=14.001(2), c=15.811(2) A , β=97.276(13)°, V=1788.0(48) A 3 , Z=4 ) and [CoCl(tacn)(ampy)]ZnCl4·H2O (monoclinic, Cc, a=20.682(9), b=7.730(3), c=15.599(7), β=124.3(4)°, V=2060.33(1.85) A 3 , Z=4 ) but [CoCl(N-Metacn)(en)]ZnCl4·H2O (monoclinic, P21/n, a=12.4930(10), b=9.685(3), c=17.109(2), β=109.610(10)°, V=1949.2(7) A 3 , Z=4 ) adopts the unsym configuration. [CoCl(dien)(bn)]ZnCl4 (monoclinic, P21/n, a=14.392(3), b=7.849(2), c=15.900(5) A , β=94.78(2)°, V=1789.9(8) A 3 , Z=4 ) contains a seven-membered coordinated 1,4-butanediamine ring and the complex adopts the unsym-fac configuration. From the reaction between NH3(aq.) and trans-[CoCl2(2,2,3-tet)]+, conglomerate crystals of trans-(R,S)-[CoCl(2,2,3-tet)(NH3)]ZnCl4 (orthorhombic, P212121 a=7.579(2), b=13.196(2), c=17.407(4) A , V=1740.9(6) A 3 , Z=4 ) can be isolated.

A general synthetic route to pentaamminecobalt(III) complexes of N-bonded amides, ureas, carbamates, sulfinamides, sulfonamides and sulfamate

A general synthetic procedure for preparing stable cobalt(III) complexes containing selectively nitrogen-bonded ambidentate molecules e.g. amides, ureas, carbamates, sulfinamides, sulfonamides and sulfamate, is described. The method relies on the superior acidity of the nitrogen-bonded, relative to the oxygen-bonded, isomer and this is attributed to much better resonance stabilization of the anionic ligand while N-bonded. Thus the method should be applicable to complexes of other metal ions.

The phenomenon of conglomerate crystallization. XXV: Spontaneous resolution in coordination compounds. The crystal structure of [cis-Co(en)2(NH3)Br]Br2

Abstract Br3CoN5C4H19, (I), crystallizes in the monoclinic system, space group C2/c, with cell constants a = 24.579(9),b = 8.665(3),c = 14.409(5) A, and β = 92.69(3)˚; V = 2988.87 A3 and d (MW = 435.875, Z = 8) = 2.097 gm cm−3. Data were collected in the range 4˚ ≤ 2θ ≤ 50˚, for a total of 2823 reflections, of which 1409 were independent and had I ≥ 3σ(I). The structure factors were corrected for absorption (μ = 90.882 cm−1) using psi scan curves obtained from reflections near X = 90˚. The transmission coefficients ranged from 0.68 to 0.99. The structure was solved by direct methods and refinement converged to final discrepancy indices of R(F) = 0.0601 and Rw(F) = 0.0663. The cobalt configuration and chelate ring conformations for (I) were found to be the preferred (lel)2-Δ(δδ) and Δ(λλ). The Co-N distances to the en rings are 1.961(6), 1.960(6), 1.977(6), 1951(6) A, while that to the -NH3 ligand is 1.963(6) A. The C-C distances are 1.52(1) and 1.50(1) A; finally, the Co-Br distance is 2.403(1) A.

Synthesis and characterisation of the seven geometric isomers of [Co(dien)(ampy)Cl]2+

Abstract All seven possible geometric [Co(dien)(ampy)Cl]2+ isomers, four mer and three facial, have been synthesised using various methods (dien=diethylenetriamine, ampy=2-aminomethylpyridine). The least abundant and most reactive m2 isomer has been synthesised using a kinetic method—an azide competition experiment—while a novel method has also been devised for the m1 isomer, obtained through its phosphato complex. The solution structures have been determined using 2D NMR techniques (DQCOSY and NOESY). A simple NMR method for distinguishing anti and syn pairs is reported.