Christine C. Allen

X-Ray Structural Studies of K6[CoII W12O40]·~16H2O and K5[CoIII W12O40]·~16H2O and Structural Trends Along the [XW12O40]– Series, where X = PV, SiIV, CoIII and CoII

The X-ray crystal structures of K6[CoII W12O40]·~16H2O and K5[CoIIIW12O40]·~16H2O are reported. The compounds are isostructural, hexagonal, space group P 6222, and have Z 3 with a 19.118(7), c 12.383(9) A, V 3919.6(35) A3 , and a 19.111(2), c 12.509(2) A, V 3956.6(9) A3 , respectively. Both anions exhibit the standard α-Keggin structure, which consists of a central tetrahedrally coordinated CoII or CoIII , surrounded by four groups of three edge-sharing octahedra (W3O13 subunits) which are linked in turn to each other and to the central CoO4 tetrahedron by shared oxygen atoms at the vertices. Although thermogravimetric analyses show that there are c. 16 water molecules per formula unit in both compounds, only six and three water molecules for the CoII and CoIII compounds, respectively, could be crystallographically located. The others are presumably zeolitic and highly disordered in nature. Structural differences between the anions on replacement of CoII by CoIII , as well as comparisons with the related [PW12O40]3– and [SiW12O40]4– ions, which contain (formally) PV and Si IV , respectively, are discussed. This comparison indicates that the W3O13 subunits become progressively more isolated with increasing size of the central heteroatom from PV to CoII , while the bonding within an individual W3O13 subunit becomes weaker. Extended-HUckel molecular orbital calculations are used to examine stability changes in the polyoxotungstate framework, using the actual polyoxotungstate geometries of the anions, on variation in size of the central heteroatom. These are compared to that in the [H3W12O40]5– ion, which has two centrally located H+ ions, but no steric effects. The studies show that no major changes occur in the overall stability of the framework, but that there is a redistribution in the contributions of the two types of bridging oxygen atoms to the stability of the framework, which parallels the progressive isolation and weaker bonding in the W3O13 subunits.

Pentapotassium dodecatungsto­borate(III) hexadecahydrate

The title compound, K5[BW12O40]·16H2O, contains a [BW12O40]5− polyanion of 222 crystallographic symmetry, with a central tetrahedrally coordinated BIII atom surrounded by four groups of three edge-sharing octahedra (W3O13 subunits), which are linked in turn to each other and to the central BO4 tetrahedron by shared O atoms at the vertices. There is a crystallographically unique B—O bond of 1.554 (10) A, while the average W—O distances are 2.344 (17) A for four coordinate O atoms, 1.917 (12) and 1.89 (2) A for two coordinate O atoms within and connecting the W3O13 subunits, respectively, and 1.709 (8) A for terminal O atoms. Not all of the K+ ions and H2O groups were located.

Electrophilic attack on diphosphazane-bridged derivatives of diruthenium nonacarbonyl by halogens. Crystal structure of [Ru2(µ-I)I(CO)3{µ-(PriO)2PN(Et)P(OPri)2}2]

Treatment of [Ru2(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2](R = Me or Pri) with halogens results in the ready formation of [Ru2X(CO)5{µ-(RO)2PN(Et)P(OR)2}2]+(X = Cl, Br or I) with the halogen atom co-ordinating terminally. These pentacarbonyl species, isolated as their hexafluorophosphate salts, decarbonylate in solution, rapidly in the presence of trimethylamine N-oxide dihydrate but slowly in the absence of this decarbonylating agent, to produce the tetracarbonyl species [Ru2(µ-X)(CO)4{µ-(RO)2PN(Et)p(OR)2}2]+ in which the halogen bridges the two ruthenium atoms. Substitution of the carbonyl groups in these tetracarbonyl species can be effected further by halide ions, either photochemically or by promoting the process using Me3NO·2H2O and thus reaction of [Ru2(µ-X)(CO)4{µ-(RO)2PN(Et)P(OR)2}2]+ with chloride, bromide or iodide ions in the presence of Me3NO·2H2O readily affords [Ru2(µ-X)X(CO)3{µ-(RO)2PN(Et)P(OR)2}2]. Significantly, treatment of [Ru2I(CO)5{µ-(RO)2PN(Et)P(OR)2}2]I3, or [Ru2I(CO)5{µ-(RO)2PN(Et)P(OR)2}2]PF6 in the presence of iodide ions, with an excess of Me3NO·2H2O leads solely to the neutral tetracarbonyl derivative [Ru2I2(CO)4{µ-(RO)2PN(Et)P(OR)2}2]. On the basis of an X-ray crystallographic study on [Ru2(µ-I)I(CO)3{µ-(PriO)2PN(Et)P(OPri)2}2], the tricarbonyl derivatives have structures related to that of [Ru2(µ-X)(CO)4{µ-(RO)2PN(Et)P(OR)2}2]+ with an axial carbonyl group having been replaced by a halide ion.

Hydrogenolysis of a pendant alcohol dithiadiazamacrocycle. Crystal structure of the 6-amino-6-methyl-1, 11-dithia-4,8-diazacyclotetradecane hydrogenolysis product as a chlorocobalt(III) complex

Abstract During extended equilibration of the potentially sexidentate ligand 6-amino-6-methyl-1, 11-dithia-4,8-diazacyclotetradecan-13-ol with cobalt ion at elevated temperature in acid in the presence of activated carbon, we observed loss of the secondary alcohol. An X-ray crystal structure characterised the hydrogenolysis product (6-amino-6-methyl-1, 11-dithia-4,8-diazacyclotetradecane) chlorocobalt(III) which crystallises in the P2 1 a space group, a = 24.800(16), b = 9.743(5), c = 26.707(9), A, β = 98.65(4)°. The cobalt ion lies in a distorted octahedral environment with the secondary amines and thioethers of the macrocycle as well as the pendant primary amine coordinated, and a chloride ion bound cis to the primary amine. Saturation of the bonds to the carbon once bonded to the alcohol group is defined by standard single CC distances (1.47–1.53 A) and albeit distorted tetrahedral geometry around all carbon centres in the carbon chain linking the secondary thioethers, supported by NMR spectroscopy.

Tetraammonium Hexahydrogenhexamolybdozincate(II) Hexahydrate

The title compound, (NH4)4(H6ZnMo6O24).6H2O, exhibits a structure with six MoO6 octahedral edge-sharing units surrounding a central ZnO6 octahedron, with all metal atoms in a common plane. The average Zn—O distance is 2.081 (5) A, while the average Mo—O distances are 2.240 (16), 1.946 (12) and 1.711 (13) A for four-, two- and single-coordinate O atoms, respectively.

Rotamers and isomers in the fulgide series. Part 3. Structures of the bis(4-methoxy-3-methylbenzylidene)succinic anhydrides

The conformation of bisarylsuccinic anhydrides is a function of steric interaction between the aryl rings and the reactivity of the substituents that they carry. To explore the second factor a methyl group has been introduced for the present study. For the first time a stable E,Z-isomer has now been isolated as a result. The structures of the E,E- and Z,Z-isomers have been determined crystallographically. Crystals of the E,E-isomer have a= 7.835(1), b= 8.966(1), c= 25.725(3)A, space group P212121, Z= 4; and for Z,Z a= 25.506(5), b= 7.896(1), c= 20.058(3)A, β= 102.75(1)°, space group C2/c, Z= 8. All efforts to obtain sufficiently large crystals of the E,Z-product have failed, but it has been characterised in terms of NMR evidence. The dehydrogenation product from ring closure of the E,Z-isomer has been characterised from its NMR spectrum and confirmed crystallographically, a= 13.132(4), b= 8.239(1), c= 17.242(7)A, β= 100.84(3)°, space group P21/c. Atomic coordinates from this structure are used to optimize the E,Z-structure by molecular modelling.

Metal-directed syntheses of dithiadiazacyclotetradecane macrocycles with pendant alcohol and nitro or carboxylate groups involving macrocycle ring expansion

Copper(II)-directed condensation of 4-hydroxymethyl-3,6-dithiaoctane-1,8-diamine with nitroethane or diethyl malonate and formaldehyde yielded (anti-6-methyl-6-nitro-1,11-dithia-4,8-diazacyclotetradecan-13-ol)copper(II) and (diethyl 13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6,6-dicarboxylate)copper(II) respectively in good yields. The latter was readily converted by decarboxylation and hydrolysis in aqueous base to the copper(II) complex of anti-13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6-carboxylic acid from which the free ligand can be obtained by zinc–acid reduction of the copper ion, whereas the former can be converted by zinc–acid reduction directly to the hydrochloride salt of the free anti-6-amino-6-methyl-1,11-dithia-4,8-diazacyclotetradecan-13-ol ligand. The condensations should yield a thirteen-membered macrocycle with a pendant hydroxymethyl group fused to a macrocyclic ring carbon, but the molecules undergo a Wagner–Meerwein or alternate carbon skeleton rearrangement to yield the fourteen-membered macrocycle with a pendant alcohol group. The pendant alcohol can act as an axial donor group, as illustrated in the crystal structure analyses of (anti-6-methyl-6-nitro-1,11-dithia-4,8-diazacyclotetradecan-13-ol)copper(II) and (anti-13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6-carboxylato)copper(II) as perchlorate salts. The former complex crystallizes in the monoclinic P21/c space group, a= 8.703(2), b= 18.699(2), c= 13.293(2)A, β= 105.15(1)° and the latter in the monoclinic P21/n space group, a= 7.450(1), b= 15.325(2), c= 16.772(1)A, β= 98.38(1)°. In both complexes the alcohol is disposed anti to the nitro or carboxylate group. In the former, the copper ion lies in a distorted-octahedral environment of two sulfur donors (Cu–Sav 2.333 A), two nitrogen donors (Cu–Nav2.016 A), the pendant alcohol donor [Cu–O 2.365(3)A] and a perchlorate anion [Cu–O 2.544(3)A], whereas in the latter a dimer with each copper in a very distorted octahedral environment exists where each carboxylate bridges to the alternate copper ion [Cu–O 2.293(3)A] and the alcohol is weakly bound [Cu–O 2.520(3)A] in addition to the macrocycle heteroatoms (Cu–Nav 2.035, Cu–Sav 2.353 A).