The synthesis, crystal structures, and magnetic properties of linear pentanuclear complexes, [Ni(5)(&mgr;(5)-tpda)(4)X(2)](n)()(+) [tpdaH(2) = tripyridyldiamine, with different axial ligands X = Cl(-) (1), CN(-) (2), N(3)(-) (3), and NCS(-) (4) (n = 0) and CH(3)CN (5) (n = 2)], are reported. All of the [Ni(5)(tpda)(4)](2+) moieties are isostructral and involve a Ni(5) linear chain unit with all of the angleNi-Ni-Ni being nearly 180 degrees, terminated by the two axial ligands. The pentanuclear linear metal chain is helically wrapped by four syn-syn-syn-syn type tpda(2-) ligands. There are two types of Ni-Ni distances existing in these complexes. The terminal Ni-Ni distances bonded with the axial ligand are longer (2.35-2.40 Å) and affected by various axial ligands. The inner Ni-Ni distances are very short and remain constant ( approximately 2.30 Å). The relationship between terminal Ni-Ni distances and properties of the axial ligands on 1-5 will be discussed. Two terminal Ni(II) ions bonded with the axial ligands are in a square-pyramidal (NiN(4)X) environment and exhibit long Ni-N bonds ( approximately 2.10 Å) which are consistent with a high-spin Ni(II) configuration. The inner three Ni(II) ions display short Ni-N ( approximately 1.90 Å) bond distances which are consistent with a square-planar (NiN(4)), diamagnetic arrangement of a low-spin Ni(II) configuration. All compounds exhibit similar magnetic behavior, indicating an antiferromagnetic interaction of two terminal high-spin Ni(II) ions in these complexes. The XANES (X-ray absorption near-edge absorption spectroscopy) spectra also confirm the existence of the high-spin and low-spin Ni(II) ions in these complexes.

Journal Article↗

PubMed1997

Syntheses and X-ray Structures of a Series of Chalcogen-Containing Manganese Carbonylates [E(2)Mn(3)(CO)(9)](-), [E(8)C(2)Mn(2)(CO)(6)](2-), and [E(2)Mn(4)(CO)(12)](2-) (E = Se, S).

The reaction of SeO(2) with Mn(2)(CO)(10)/KOH in methanol solution forms a trigonal bipyramid cluster anion [Se(2)Mn(3)(CO)(9)](-) (Ia). Cluster Ia can also be synthesized from the treatment of Se powder with Mn(2)(CO)(10)/KOH in 2:1 molar ratio in methanol solution. If Se is reacted with Mn(2)(CO)(10)/KOH in a molar ratio of 8:1, the deoxygenation occurs to produce a novel cluster [Se(8)C(2)Mn(2)(CO)(6)](2)(-) (IIa). Cluster IIa can readily transform into a new octahedral cluster [Se(2)Mn(4)(CO)(12)](2)(-) (IIIa) by further treatment with Mn(2)(CO)(10)/KOH in CH(2)Cl(2)/MeOH solutions, and the use of a molar ratio of 1:1 of Se powder to Mn(2)(CO)(10)/KOH in methanol also can yield complex IIIa. In the sulfur-manganese system, the synthesis of the analogous complexes [S(2)Mn(3)(CO)(9)](-) (Ib), [S(8)C(2)Mn(2)(CO)(6)](2)(-) (IIb), and [S(2)Mn(4)(CO)(12)](2)(-) (IIIb) also can be accomplished from the reactions of S powder with Mn(2)(CO)(10)/KOH in similar fashions. Clusters Ia-IIIa and Ib-IIIb are fully characterized by spectroscopic methods or/and X-ray analyses. The novel clusters [E(8)C(2)Mn(2)(CO)(6)](2)(-) (E = Se, IIa; E = S, IIb) each consist of two separate Mn(CO)(3) groups which are doubly bridged by two CE(4) fragments. Clusters Ia and Ib each display a trigonal bipyramid framework with two chalcogen atoms in the axial positions, while clusters IIIa and IIIb each exhibit an octahedral metal skeleton.

Journal Article↗

PubMed1997

Substitution Reactions of Aluminum Organoamide Complexes [Al(&mgr;-NR(2))(n)Cl(3-n)](2) (R = Et, (i)Pr; n </= 3) with LiNR'R" (R' = R" = (i)Pr, Et; R' = H, R" = (i)Pr): Crystal Structure of [Al(&mgr;-NEt(2))(N(i)Pr(2))X](2) (X = Cl, H) and AlCl(3)(N(i)PrH(2))(2){Al(NH(3))(NH(2))[Al(N(i)PrH)(N(i)Pr)Cl](2)}(2).

As part of our ongoing study of different substituents of Al(2)N(2) ring systems, the synthesis, structural characterization, and spectroscopic studies on several amido derivatives of four-coordinated aluminum are described. The compounds Al(2)(NEt(2))(2)(N(i)Pr(2))(2)Cl(2), 1, Al(2)((N(i)Pr(2))(4)Cl(2), 2, Al((N(i)Pr(2))(3), 3, Al(NEt(2))(3), 4, {Al(N(i)PrH)(3)}(3), 5, Al(2)(NEt(2))(2)(N(i)Pr(2))(2)H(2), 6, and AlCl(3)(N(i)PrH(2))(2){Al(NH(3))(NH(2))[Al(N(i)PrH)(N(i)Pr)Cl](2)}(2), 7, were synthesized by substitution reactions and characterized by mass spectra, IR spectra, elemental analysis, and (1)H, (13)C, and (27)Al NMR data. The structures of three compounds, viz., 1, 6, and 7, have been determined by single-crystal X-ray diffraction analysis. Crystal data with Mo Kalpha (1 and 7, lambda = 0.710 73 Å) or Cu Kalpha (6, lambda = 1.541 78 Å) radiation: (1) Al(2)N(4)C(20)H(48)Cl(2), a = 7.747(2) Å, b = 9.648(2) Å, c = 10.110(3) Å, alpha = 102.91(2) degrees, beta = 83.54(2) degrees, gamma = 110.19(2) degrees, triclinic, space group P&onemacr;, Z = 1, R = 0.053 for 1789 (I > 3sigma(I)) reflections; (6) Al(2)N(4)C(20)H(50), a = 15.088(2) Å, b = 14.506(3) Å, c = 12.439(3) Å, orthorhombic, space group Cmca (No. 64), Z = 4, R = 0.045 for 701 (I > 3sigma(I)) reflections; (7) Al(7)N(14)C(30)H(86)Cl(7), a = 29.914(9) Å, b = 10.197(3) Å, c = 20.525(5) Å, beta = 90.99(4) degrees, monoclinic, space group C2/c, Z = 4, R = 0.042 for 2472 (I > 2sigma(I)) reflections.

Journal Article↗

PubMed1997

Heterometallic Complexes with Selenolate Ligands: Crystal Structures of [(CO)(3)Mn(&mgr;-SePh)(3)Co(&mgr;-SePh)(3)Mn(CO)(3)](-), (CO)(4)Mn(&mgr;-SeMe)(2)Co(CO)(&mgr;-SeMe)(3)Mn(CO)(3), and [(CO)(3)Mn(&mgr;-SePh)(3)Mn(CO)(3)](-).

Oxidation of Co(2+) by diphenyl diselenide in the presence of cis-[PPN][Mn(CO)(4)(SePh)(2)], followed by carbonyl shift from Mn(I) to Co(III) and a benzeneselenolate group rearranging to bridge two metals, led directly to the thermally unstable (CO)(4)Mn(&mgr;-SePh)(2)Co(CO)(&mgr;-SePh)(3)Mn(CO)(3). Dropwise addition of [PPN][SePh] to the neutral (CO)(4)Mn(&mgr;-SePh)(2)Co(CO)(&mgr;-SePh)(3)Mn(CO)(3) resulted in formation of a linear trinuclear complex possessing a hexaselenolatecobalt(III) core, [PPN][(CO)(3)Mn(&mgr;-SePh)(3)Co(&mgr;-SePh)(3)Mn(CO)(3)]. This complex crystallized in the triclinic space group P&onemacr; with a = 10.878(1) Å, b = 15.095(2) Å, c = 25.372(4) Å, alpha = 95.04(1) degrees, beta = 95.00(1) degrees, gamma = 91.52(2) degrees, V = 4132(2) Å(3), and Z = 2; final R = 0.042 and R(w) = 0.042. In contrast, the thermally unstable cis-[PPN][Mn(CO)(4)(SeMe)(2)], which was reacted with Co(ClO(4))(2).6H(2)O and (MeSe)(2) in THF under a nitrogen atmosphere, led to the isolation of the stable heterometallic selenolate (CO)(4)Mn(&mgr;-SeMe)(2)Co(CO)(&mgr;-SeMe)(3)Mn(CO)(3). Crystal data: monoclinic space group C2/c, a = 28.413(7) Å, b = 11.091(3) Å, c = 22.849(6) Å, beta = 125.06(3) degrees, V = 5894(3) Å(3), and Z = 8; final R = 0.047 and R(w) = 0.048. The results indicated that the distinct electronic effects between methaneselenolate and benzeneselenolate play a key role in stabilizing the neutral Mn(I)-Co(III)-Mn(I)-selenolate complexes.

Journal Article↗

PubMed1996

Reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] with Alkyl Halides and Dihalides: Formation of the Alkyl- and the Dialkylantimony-Iron Carbonyl Complexes.

The reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] (1) with RX (R = Me, Et, n-Pr; X = I) in MeCN form the monoalkylated antimony complexes [Et(4)N](2)[RSb{Fe(CO)(4)}(3)] (R = Me, 2; R = Et, 4; R = n-Pr, 6) and the dialkylated antimony clusters [Et(4)N][R(2)Sb{Fe(CO)(4)}(2)] (R = Me, 3; R = Et, 5; R = n-Pr, 7), respectively. When [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] reacts with i-PrI, only the monoalkylated antimony complex [Et(4)N](2)[i-PrSb{Fe(CO)(4)}(3)] (8) is obtained. The mixed dialkylantimony complex [Et(4)N][MeEtSb{Fe(CO)(4)}(2)] (9) also can be synthesized from the reaction of 2 with EtI. While the reaction with Br(CH(2))(2)Br produces [Et(4)N](2)[BrSb{Fe(CO)(4)}(3)] (10), treatment with Cl(CH(2))(3)Br forms the monoalkylated product [Et(4)N](2)[Cl(CH(2))(3)Sb{Fe(CO)(4)}(3)] (11) and a dialkylated novel antimony-iron complex [Et(4)N][{&mgr;-(CH(2))(3)}Sb{Fe(CO)(4)}(3)] (12). On the other hand, the reaction with Br(CH(2))(4)Br forms the monoalkylated antimony product and the dialkylated antimony complex [Et(4)N][{&mgr;-(CH(2))(4)}Sb{Fe(CO)(4)}(2)] (13). Complexes 2-13 are characterized by spectroscopic methods or/and X-ray analyses. On the basis of these analyses, the core of the monoalkyl clusters consists of a central antimony atom tetrahedrally bonded to one alkyl group and three Fe(CO)(4) fragments and the dialkyl products are structurally similar to the monoalkyl clusters, with the central antimony bonded to two alkyl groups and two Fe(CO)(4) moieties in each case. The dialkyl complex 3 crystallizes in the monoclinic space group P2(1)/c with a = 13.014(8) Å, b = 11.527(8) Å, c = 17.085(5) Å, beta = 105.04(3) degrees, V = 2475(2) Å(3), and Z = 4. Crystals of 12 are orthorhombic, of space group Pbca, with a = 14.791(4) Å, b = 15.555(4) Å, c = 27.118(8) Å, V = 6239(3) Å(3), and Z = 8. The anion of cluster 12 exhibits a central antimony atom bonded to three Fe(CO)(4) fragments with a -(CH(2))(3)- group bridging between the Sb atom and one Fe(CO)(4) fragment. This paper discusses the details of the reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] with a series of alkyl halides and dihalides. These reactions basically proceed via a novel double-alkylation pathway, and this facile methodology can as well provide a convenient route to a series of alkylated antimony-iron carbonyl clusters.

Journal Article↗

PubMed1996

Bis(amido)ruthenium(IV) Complexes with 2,3-Diamino-2,3-dimethylbutane. Crystal Structure and Reversible Ru(IV)-Amide/Ru(III)-Amine and Ru(IV)-Amide/Ru(II)- Amine Redox Couples in Aqueous Solution.

Two bis(amido)ruthenium(IV) complexes, [Ru(IV)(bpy)(L-H)(2)](2+) and [Ru(IV)(L)(L-H)(2)](2+) (bpy = 2,2'-bipyridine, L = 2,3-diamino-2,3-dimethylbutane, L-H = (H(2)NCMe(2)CMe(2)NH)(-)), were prepared by chemical oxidation of [Ru(II)(bpy)(L)(2)](2+) and the reaction of [(n-Bu)(4)N][Ru(VI)NCl(4)] with L, respectively. The structures of [Ru(bpy)(L-H)(2)][ZnBr(4)].CH(3)CN and [Ru(L)(L-H)(2)]Cl(2).2H(2)O were determined by X-ray crystal analysis. [Ru(bpy)(L-H)(2)][ZnBr(4)].CH(3)CN crystallizes in the monoclinic space group P2(1)/n with a = 12.597(2) Å, b = 15.909(2) Å, c = 16.785(2) Å, beta = 91.74(1) degrees, and Z = 4. [Ru(L)(L-H)(2)]Cl(2).2H(2)O crystallizes in the tetragonal space group I4(1)/a with a = 31.892(6) Å, c = 10.819(3) Å, and Z = 16. In both complexes, the two Ru-N(amide) bonds are cis to each other with bond distances ranging from 1.835(7) to 1.856(7) Å. The N(amide)-Ru-N(amide) angles are about 110 degrees. The two Ru(IV) complexes are diamagnetic, and the chemical shifts of the amide protons occur at around 13 ppm. Both complexes display reversible metal-amide/metal-amine redox couples in aqueous solution with a pyrolytic graphite electrode. Depending on the pH of the media, reversible/quasireversible 1e(-)-2H(+) Ru(IV)-amide/Ru(III)-amine and 2e(-)-2H(+) Ru(IV)-amide/Ru(II)-amine redox couples have been observed. At pH = 1.0, the E degrees is 0.46 V for [Ru(IV)(bpy)(L-H)(2)](2+)/[Ru(III)(bpy)(L)(2)](3+) and 0.29 V vs SCE for [Ru(IV)(L)(L-H)(2)](2+)/[Ru(III)(L)(3)](3+). The difference in the E degrees values for the two Ru(IV)-amide complexes has been attributed to the fact that the chelating saturated diamine ligand is a better sigma-donor than 2,2'-bipyridine.

Journal Article↗

PubMed1996

An Approach to Heterometallic Complexes with Selenolate and Tellurolate Ligands: Crystal Structures of cis-[Mn(CO)(4)(SePh)(2)](-), [(CO)(3)Mn(&mgr;-SeMe)(3)Mn(CO)(3)](-), (CO)(4)Mn(&mgr;-TePh)(2)Co(CO)(&mgr;-SePh)(3)Mn(CO)(3), and (CO)(3)Mn(&mgr;-SePh)(3)Fe(CO)(3).

Oxidative addition of diorganyl diselenides to the coordinatively unsaturated, low-valent transition-metal-carbonyl fragment [Mn(CO)(5)](-) produced cis-[Mn(CO)(4)(SeR)(2)](-). The complex cis-[PPN][Mn(CO)(4)(SePh)(2)] crystallized in triclinic space group P&onemacr; with a = 10.892(8) Å, b = 10.992(7) Å, c = 27.021(4) Å, alpha = 101.93(4) degrees, beta = 89.79(5) degrees, gamma = 116.94(5) degrees, V = 2807(3) Å(3), and Z = 2; final R = 0.085 and R(w) = 0.094. Thermolytic transformation of cis-[Mn(CO)(4)(SeMe)(2)](-) to [(CO)(3)Mn(&mgr;-SeMe)(3)Mn(CO)(3)](-) was accomplished in high yield in THF at room temperature. Crystal data for [Na-18-crown-6-ether][(CO)(3)Mn(&mgr;-SeMe)(3)Mn(CO)(3)]: trigonal space group R&thremacr;, a = 13.533(3) Å, c = 32.292(8) Å, V = 5122(2) Å(3), Z = 6, R = 0.042, R(w) = 0.041. Oxidation of Co(2+) to Co(3+) by diphenyl diselenide in the presence of chelating metallo ligands cis-[Mn(CO)(4)(SePh)(2)](-) and cis-[Mn(CO)(4)(TePh)(2)](-), followed by a bezenselenolate ligand rearranging to bridge two metals and a labile carbonyl shift from Mn to Co, led directly to [(CO)(4)Mn(&mgr;-TePh)(2)Co(CO)(&mgr;-SePh)(3)Mn(CO)(3)]. Crystal data: triclinic space group P&onemacr;, a = 11.712(3) Å, b = 12.197(3) Å, c = 15.754(3) Å, alpha = 83.56(2) degrees, beta = 76.13(2) degrees, gamma = 72.69(2) degrees, V = 2083.8(7) Å(3), Z = 2, R = 0.040, R(w) = 0.040. Addition of fac-[Fe(CO)(3)(SePh)(3)](-) to fac-[Mn(CO)(3)(CH(3)CN)(3)](+) resulted in formation of (CO)(3)Mn(&mgr;-SePh)(3)Fe(CO)(3). This neutral heterometallic complex crystallized in monoclinic space group P2(1)/n with a = 8.707(2) Å, b = 17.413(4) Å, c = 17.541(4) Å, beta = 99.72(2) degrees, V = 2621(1) Å(3), and Z = 4; final R = 0.033 and R(w) = 0.030.

Journal Article↗