K. Vidyasagar

Preparation and structural characterization of three tetrakis(triazeno)diruthenium compounds

Abstract Three closely related diruthenium triazeno complexes, Ru2[(p-tolyl)NNN(p-tolyl)]4(CH3CN) (1), Ru2(PhNNNPh)4 (2) and Ru2[(p-tolyl)NNN(p-tolyl)]4(CH3CN)·BF4 (3), have been synthesized and structurally characterized. Direct cocrystallization of Ru2[(p-tolyl)NNN(p-tolyl)]4 with CH3CN affords the dark red 1 in space group P4/n with a=14.851(3), c=11.942(7) A, V=2634(2) A3 and Z=2. The purple 2 was crystallized in space group P 1 with a=13.720(5), b=15.901(4), c=10.388(4) A, α=103.92(3), β=94.56(3), γ=99.11(3)°, V=2155(1) A3 and Z=2. The dark green 3 was obtained by oxidizing Ru2[(p-tolyl)NNN(p-tolyl)]4 with Ag(CH3CN)4BF4, and crystallized in space group P2/n with a=13.280(2), b=16.816(5), c=13.095(4) A, β=90.16(2)°, V=2924(2) A3 and Z=2. The RuRu bond lengths determined through diffraction studies are 2.407(1), 2.3994(6) and 2.373(1) A for 1, 2 and 3, respectively. The results of both magnetic susceptibility and EPR measurements on 3 consistently confirm a π*3 ground state configuration as previously predicted.

The crystal structure of [(n-C4H9)4N]2Re2I8: Three-fold disorder of the effectively cubic anion

Abstract The title compound was prepared by the method of Preetz and Rudzik and its structure determined by single-crystal X-ray diffractometry. It crystallizes in the rhombohedral system, space group R 3 with the following (hexagonal) unit cell dimensions: a = 12.185(2), c = 30.195(3) A, V = 3882(2) A3, Z = 3. The set of iodine atoms defines an essentially perfect cube that resides on a crystallographic 3 position. Within this essentially cubic rhombohedron the two Re atoms are disordered over six positions that define an essentially octahedral trigonal antiprism. Pairs of opposite vertices of this octahedron correspond to Re26+ units which have an internuclear distance of 2.245(3) A. The ReI distances are 2.700(3), 2.711(3) and 2.715(2) A to the six equivalent I atoms and 2.647(3) A to the other pair. The ReReI angles all lie in the range 104.8(1)–105.9(1)°. The relationship of this structure to those of other octahalo dimetal compounds is discussed.

Three new dicarboxylatodirhenium(III) compounds and their structures: a structure type not previously seen

Three new structures of compounds containing the Re 2 (O 2 CR) 2 X 4 unit are reported and two are shown to contain features rarely or not previously observed. Reaction of trimeric ReCl 3 and PhCOONa in THF under reflux conditions for 24 h gave dark-green orthorhombic crystals of the THF solvate cis -Re 2 (O 2 CPh) 2 Cl 4 (THF) 2 ·THF ( 1 ). The crystals belong to the space group Pbcm with unit cell dimensions a = 8.867(2), b = 19.851(4), c = 18.022(4) A, V = 3172(2) A 3 , and D calc = 2.037 g/cm 3 for Z = 4. The structure was refined to R = 0.037 and R w = 0.046 for 1825 reflections having I >3σ( I ). Reaction of [(n-C 4 H 9 ) 4 N] 2 Re 2 Cl 8 and NaF in acetonitrile under reflux conditions for 4 days followed by work-up in acetone gave blue, monoclinic crystals of cis -[(n-C 4 H 9 ) 4 N][Re 2 (O 2 CCH 3 )Cl 5 ]· (CH 3 ) 2 CO ( 2 ).The crystals belong to the space group P 2 1 / n with unit cell dimensions a = 11.283(4), b = 13.577(5), c = 21.835(10) A, V = 3345(4) A 3 , and D calc = 1.923 g/cm 3 for Z = 4. The structure was refined to R = 0.056 and R w = 0.066 for 2443 reflections having I >3σ( I ). Compound 3 , [ReCl 2 (dpcp) 2 ][Re 2 (O 2 CPh) 2 Cl 6 ]·CHCl 3 contains the first example of an axially coordinated species with a transoid arrangement of the carboxylate ligands. 3 crystallizes in space group P with a = 13.372(4), b = 14.067(6), c = 10.899(7) A, α = 99.694(5)°, β = 103.030(5)°, γ = 84.501(3)°, V = 1966(3) A 3 , Z = 1. The structure was refined to R = 0.067 and R w = 0.082 for 2648 reflections with I >3σ( I ).

Complexes of molybdenum(III) and -(IV) with chloride and tertiary phosphine ligands; an omniumgatherum of new and old results

The preparations and structures of four new mixed chloro-tertiary phosphine complexes {Bd1, 3–5} of molybdenum(III) are reported, as well as the structure of two previously known MoIII complexes {Bd2,6} and the structure of an [MoCl6]2− compound {Bd7}. These results are discussed along with data for other such compounds.

Crystallographic disorder of the Re2 unit in complexes of the type A2Re2X8 (A=HP-n-Pr3, PMePh3; XCl or Br)

Abstract The preparation and structural characterization of three complexes containing the [Re2X8]2− (X=Cl or Br) anion are described. Crystallographic parameters are as follows: for [HPnPr3]2Re2Cl8 (1) a=33.831(9), b=11.274(6), c=18.286(5) A, β=91.11(1)°, V=6955(7) A3, Z=8, space group C2/c; for [PMePh3]2Re2Cl8 (2) a=10.861(2), b=11.964(3), c=16.235(4) A, β=93.40(2)°, V=2106(1), Z=2, space group P21/n; for [PMePh3]2Re2Br8 (3) a=10.964(2), b=12.198(2), c=16.421(2) A, β=93.83(1)°, V=2191(1) A3, Z=2, space group P21/n. These complexes exhibit an unusual form of crystallographic disorder which has been previously observed in other derivatives that contain the [Re2X8]2− anion. It is suggested that while this type of disorder must correlate with the positions of the cations relative to the anions in the crystal packing, and other factors, no simple analysis is likely to be adequate.

Preparation and structure of the face-sharing bioctachedral ion [Mo2Cl8(PEt3)]2−

The reaction of [PPh4][MoCl4(THF)2] with PEt3 affords [PPh4]2[Mo2Cl8(PEt3)] as a dark red solid with two molecules of Ch2Cl2 of crystallization. The crystals are triclinic (P1) with Z = 2 for a unit cell of the following dimensions: a = 13.168(5), b = 21.436(6), c = 11.852(4) A, α = 91.16(3), β = 100.07(3), γ = 107.22(3)°, V = 3337 A3. In the face-sharing bioctahedral (FSBO) anion, the MoMo distance is 2.767(2) A. The structure is compared to a number of other FSBO structures of general formula Mo2Cl9−n(PR3)n.

A compound containing two [Os2I8]2− ions fused to form a [Os4I14]2− ion containing OsOs triple bonds

The series of Os 2 X 8 2− ions, previously known only with X = Cl and Br, has now been extended to include the iodide, albeit with a centrosymmetric tetranuclear anion consisting of two staggered Os 2 I 8 units joined by sharing of two iodine atoms that form an edge approximately perpendicular to the metalmetal bonds. The complete formula of the compound is [PMePh 3 ] 2 Os 4 I 14 . The OsOs distance, 2.231 A, is the longest OsOs distance yet reported in Os 2 X 8 2− species. The compound was made by treating the pink ‘[Pmeph 3 ] 2 Os 2 Cl 8 ’ (obtained from Os 2 (OAc) 4 Cl 2 ) with HI gas at room temperature. Crystallographic data: space group P , a = 12.617(2), b = 14.421(2), c = 9.386(2) A, α = 91.32(1), β = 100.32(1), γ = 113.97(1)°, V = 1526(1)A 3 , Z = 1.

Three-fold disordering of the Re2 unit in the Re2Cl6(PEt3)2 molecule

Abstract When crystallized from toluene, Re2Cl6(PEt3)2 forms crystals that incorporate interstitial toluene molecules, and have the composition Re2Cl6(PEt3)2· C7H8. Space group R 3 c, with a = 12.433(5), c = 32.549(10) A, V = 4357(1) A3 and Z = 6. The two rhenium atoms are disordered over six positions that form an octahedron within a cubic rhombohedron defined by six chlorine and two phosphorus atoms, and centered at a crystallographic 3 position. The disorder is analogous to that previously found in [N(C4H9)4]2Re2I8.