Synthesis and magnetic properties of a [Ni(II)(TCNE)(NCMe)2-delta][BF4] magnet (Tc = 40 K)

The reaction of (NBu4)(TCNE) (TCNE = tetracyanoethylene) and [Ni(NCMe)6][BF4]2 in CH2Cl2 forms layered [Ni(TCNE)(MeCN)2-delta][BF4], a magnet ( Tc = 40 K) with a ferromagnetic interaction within Ni-mu 4-[TCNE](*-) layers, and a new general route to the preparation of [M(TCNE)(NCMe)2][anion] magnets has been identified.     

Magnetic ordering (Tc = 90 K) observed for layered [Fe(II)(TCNE*-)(NCMe)2]+[Fe(III)Cl4]- (TCNE = tetracyanoethylene)

[Fe(TCNE)(NCMe)2][FeCl4] is isolated from the reaction of TCNE and FeCl2(NCMe)2 and orders as a ferrimagnet below 90 K and is the initial member of a new class of magnets. It is the first metal-TCNE magnet with direct bonding between metal ion and [TCNE]*- whose structure has been determined, and it possesses a novel planar mu4-[TCNE]*- spin coupling unit bonded to four FeII's, with an axial pair of MeCNs. The [FeIIICl4]- anion occupies sites between the [FeII(TCNE*-)(NCMe)2]+ layers. [Fe(TCNE)(NCMe)2][FeCl4] has a coercive field of 1730 Oe and a remnant magnetization of 7500 emuK/mol at 50 K.     

Acetonitrile-facilitated reductive dimerization of TCNE to octacyanobutanediide, [C4(CN)8]2-, by Iron(II) chloride

The redox properties of MCl2 (M=Mn, Fe, Co) acetonitrile solvates were electrochemically and spectroscopically characterized. The three voltammogram waves at 0.86, 0.48, and 0.21 V versus SCE for FeCl(2) dissolved in MeCN are assigned as one-electron reduction potentials for [Fe(II)Cl(x)(NCMe)4-x]2-x (1相似文献   

Synthesis and magnetic properties of 3-D [Ru(II/III)(2)(O(2)CMe)(4)](3)[M(III)(CN)(6)] (M = Cr,Fe, Co)

Three-dimensional network structures of [Ru(II/III)(2)(O(2)CMe)(4)](3)[M(III)(CN)(6)] (M = Cr, Fe, Co) composition have been formed and their magnetic properties characterized. [Ru(II/III)(2)(O(2)CMe)(4)](3)[M(III)(CN)(6)] (M = Cr, Fe, Co) have nu(CN) IR absorptions at 2138, 2116, and 2125 cm(-1) and have body-centered unit cells (a = 13.34, 13.30, and 13.10 A, respectively) with -M-Ctbd1;N-Ru=Ru-Ntbd1;C-M- linkages along all three Cartesian axes. [Ru(II/III)(2)(O(2)CMe)(4)](3)[Cr(III)(CN)(6)] magnetically orders as a ferrimagnet (T(c) = 33 K) and has an unusual constricted hysteresis loop.     

TCNE dimer dianion coordination complexes, [Mn(TPA)(TCNE)]2[micro2-(TCNE)2] and [Mn(TPA)(micro4-C4(CN)8)0.5].ClO4, TPA=tris(2-pyridylmethyl)amine: synthesis, structure and magnetic properties

The structures and magnetic properties of two products that result from the reactions of [Mn(TPA)(CH3CN)2](ClO4)2, TPA=tris(2-pyridylmethyl)amine and potassium tetracyanoethylenide, KTCNE, are reported. [Mn(TPA)(TCNE)]2[mu2-(TCNE)2] (1) and [Mn(TPA)(micro4-C4(CN)8)0.5].ClO4 (2) are obtained by using two different ratios of the initial reactants. Each was intended to possess two or more cis-TCNE radical anions (TCNE*/-) as ligands. 1 is a dinuclear species that crystallizes in the triclinic system in the space group P, with a=10.4432(17), b=12.2726(16), and c=13.708(2) A; alpha=88.505(12), beta=75.560(14), and gamma=87.077(12) degrees; V=1698.9(4) A3; and Z=1 and features two metal centers each with three nearly orthogonal TCNE*/- ligands. However, the three TCNE*/- ligands are all dimerized via the formation of four-center, two-electron bonds: two bridge the two Mn(II) centers, and a third TCNE*/- ligand forms an intermolecular bond to another equivalent TCNE*/-. 2 crystallizes in the tetragonal system in the space group P42212, with a=17.170(3), b=17.170(3), and c=17.1837(6) A; V=5065.9(13) A3; and Z=8. It consists of a ribbon-like coordination polymer containing the previously observed but still relatively rare octacyanobutyl dianion. The [C4(CN)8]2- anion is derived from the dimerization of two TCNE radical anions via the formation of a new sigma bond, and each anion bridges four Mn(II) centers. Both 1 and 2 display magnetic behavior consistent with only weak antiferromagnetic coupling between the high-spin d5 Mn(II) in which the TCNE*/- are rendered diamagnetic through dimerization.     

Magnetic ordering in the rare earth molecule-based magnets,Ln(TCNE)(3) (Ln = Gd,Dy; TCNE = tetracyanoethylene)

The reaction of LnI(3) x xMeCN (Ln = Gd, Dy) and TCNE (tetracyanoethylene) in acetonitrile forms Ln(2)[C(4)(CN)(8)](3) x xMeCN. These paramagnetic light-colored solids contain the S = 0 octacyanobutandiide dianion, [C(4)(CN)(8)](2-), which upon desolvation of these products forms dark green Ln(TCNE)(3). In these compounds the central C[bond]C sigma bond in [C(4)(CN)(8)](2-) is broken, re-forming S = 1/2 [TCNE]*(-). as evidenced by the color change and the infrared spectra. Ln(TCNE)(3) exhibit coupling between Ln(3+) and [TCNE]*(-) and magnetically order as ferrimagnets at 8.5 (Dy) and 3.5 (Gd) K.     

Oxalate-based soluble 2D magnets: the series [K(18-crown-6)]3[M(II)3(H2O)4{M(III)(ox)3}3] (M(III) = Cr, Fe; M(II) = Mn, Fe, Ni, Co, Cu; ox = C2O4(2-); 18-crown-6 = C12H24O6)

The synthesis and magnetic properties of the oxalate-based molecular soluble magnets with general formula [K(18-crown-6)] 3[M (II) 3(H 2O) 4{M (III)(ox) 3} 3] (M (III) = Cr, Fe; M (II) = Mn, Fe, Ni, Co, Cu; ox = C 2O 4 (2-)) are here described. All the reported compounds are isostructural and built up by 2D bimetallic networks formed by alternating M (III) and M (II) ions connected through oxalate anions. Whereas the Cr (III)M (II) derivatives behave as ferromagnets with critical temperatures up to 8 K, the Fe (III)M (II) present ferri- or weak ferromagnetic ordering up to 26 K.     

Heterobimetallic Clusters of Copper(I) with Trithiotungstate and Trithiomolybdate. Synthesis and Characterization of the Octanuclear Clusters [Et(4)N](4)[M(4)Cu(4)S(12)O(4)] (M = Mo, W) and the Dodecanuclear Clusters [M(4)Cu(4)S(12)O(4)(CuTMEN)(4)] (M = Mo, W; TMEN = N,N,N',N'-Tetramethylethylenediamine)

Synthetic methods for [Et(4)N](4)[W(4)Cu(4)S(12)O(4)] (1), [Et(4)N](4)[Mo(4)Cu(4)S(12)O(4)] (2), [W(4)Cu(4)S(12)O(4)(CuTMEN)(4)] (3), and [Mo(4)Cu(4)S(12)O(4)(CuTMEN)(4)] (4) are described. [Et(4)N](2)[MS(4)], [Et(4)N](2)[MS(2)O(2)], Cu(NO(3))(2).3H(2)O, and KBH(4) (or Et(4)NBH(4)) were used as starting materials for the synthesis of 1 and 2. Compounds 3 and 4 were produced by reaction of [Et(4)N](2)[WOS(3)], Cu(NO(3))(2).3H(2)O, and TMEN and by reaction of [Me(4)N](2)[MO(2)O(2)S(8)], Cu(NO(3))(2).3H(2)O, and TMEN, respectively. Crystal structures of compounds 1-4 were determined. Compounds 1 and 2 crystallized in the monoclinic space group C2/c with a = 14.264(5) ?, b = 32.833(8) ?, c = 14.480(3) ?, beta = 118.66(2) degrees, V = 5950.8(5) ?(3), and Z = 4 for 1 and a = 14.288(5) ?, b = 32.937(10) ?, c = 14.490(3) ?, beta = 118.75(2) degrees, V = 5978.4(7) ?(3), and Z = 4 for 2. Compounds 3 and 4 crystallized in the trigonal space group P3(2)21 with a = 13.836(6) ?, c = 29.81(1) ?, V = 4942(4) ?(3), and Z = 3 for 3 and a = 13.756(9) ?, c = 29.80(2) ?, V = 4885(6) ?(3), and Z = 3 for 4. The cluster cores have approximate C(2v) symmetry. The anions of 1 and 2 may be viewed as consisting of two butterfly-type [CuMOS(3)Cu] fragments bridged by two [MOS(3)](2-) groups. Eight metal atoms in the anions are arranged in an approximate square configuration, with a Cu(4)M(4)S(12) ring structure. Compounds 3 and 4 can be considered to consist of one [M(4)Cu(4)S(12)O(4)](4-) (the anions of 1 and 2) unit capped by Cu(TMEN)(+) groups on each M atom; the Cu(TMEN)(+) groups extend alternately up and down around the Cu(4)M(4) square. The electronic spectra of the compounds are dominated by the internal transitions of the [MOS(3)](2-) moiety. (95)Mo NMR spectral data are investigated and compared with those of other compounds.     

Synthesis, characterization, and chiral behavior of S-bridged Co(III)Pt(II)Co(III) trinuclear complexes composed of bis(thiolato)-type octahedral units cis(S)-[Co(aet)(2)(en)](+) and/or trans(N)-[Co(D-pen- N,O,S)(2)](-) (aet = 2-aminoethanethiolate, D-pen = D-penicillaminate)

A series of linear-type Co(III)Pt(II)Co(III) trinuclear complexes composed of C(2)-cis(S)-[Co(aet)(2)(en)](+) (aet = 2-aminoethanethiolate) and/or Lambda(D)-trans(N)-[Co(D-pen-N,O,S)(2)](-) (D-pen = D-penicillaminate) were newly prepared, and their chiral behavior, which is markedly different from that of the corresponding Co(III)Pd(II)Co(III) complexes, is reported. The 1:1 reaction of an S-bridged Co(III)Ni(II)Co(III) trinuclear complex, [Ni[Co(aet)(2)(en)](2)]Cl(4), with K(2)[PtCl(4)] in water gave an S-bridged Co(III)Pt(II)Co(III) trinuclear complex, [Pt[Co(aet)(2)(en)](2)]Cl(4) ([1]Cl(4)), while the corresponding 1:2 reaction produced an S-bridged Co(III)Pt(II) dinuclear complex, [PtCl(2)[Co(aet)(2)(en)]]Cl ([2]Cl). Complex [1](4+) formed both racemic (DeltaDelta/LambdaLambda) and meso (DeltaLambda) forms, which were separated and optically resolved by cation-exchange column chromatography. An optically active S-bridged Co(III)Pt(II)Co(III) trinuclear complex having the pseudo LambdaLambda configuration, Lambda(D)Lambda(D)-[Pt[Co(D-pen-N,O,S)(2)](2)](0) (Lambda(D)Lambda(D)-[3]), was also prepared by reacting Lambda(D)-trans(N)-K[Co(D-pen-N,O,S)(2)] with K(2)[PtCl(4)] in a ratio of 2:1 in water. Treatment of the racemic Delta/Lambda-[2]Cl with Lambda(D)-trans(N)-K[Co(D-pen-N,O,S)(2)] in a ratio of 1:1 in water led to the formation of LambdaLambda(D)- and DeltaLambda(D)-[Pt[Co(aet)(2)(en)][Co(D-pen-N,O,S)(2)]](2+) (LambdaLambda(D)- and DeltaLambda(D)-[4](2+)) and DeltaDelta(D)-[Pt[Co(aet)(2)(en)][Co(D-pen-N,S)(2)(H(2)O)(2)]](2+) (DeltaDelta(D)-[4'](2+)), besides trace amounts of Lambda(D)Lambda(D)-[3] and DeltaDelta- and DeltaLambda-[1](4+). These Co(III)Pt(II)Co(III) complexes were characterized on the basis of electronic absorption, CD, and NMR spectra, along with single-crystal X-ray analyses for DeltaDelta/LambdaLambda-[1]Cl(4), DeltaLambda-[1]Cl(4), and DeltaLambda(D)-[4]Cl(2). Crystal data: DeltaDelta/LambdaLambda-[1]Cl(4).6H(2)O, monoclinic, space group C2/c with a = 14.983(3) A, b = 19.857(4) A, c = 12.949(3) A, beta = 113.51(2) degrees, V = 3532(1) A(3), Z = 4; DeltaLambda-[1]Cl(4).3H(2)O, orthorhombic, space group Pbca with a = 14.872(3) A, b = 14.533(3) A, c = 14.347(2) A, V = 3100(1) A(3), Z = 4; DeltaLambda(D)-[4]Cl(2).6H(2)O, monoclinic, space group P2(1) with a = 7.3836(2) A, b = 20.214(1) A, c = 10.622(2) A, beta = 91.45(1) degrees V = 1682.0(4) A(3), Z = 2.     

Cyano-bridged bimetallic assemblies from hexacyanometalate, [M(CN)6](3-) (M = Mn(III) and Fe(III)), and [M(N4-macrocycle)]2+ (M=Fe(III), Ni(II) and Zn(II)) building blocks. Syntheses, multidimensional structures, and magnetic properties

Reactions between [M(N(4)-macrocycle)](2+) (M = Zn(II) and Ni(II); macrocycle ligands are either CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane or cyclam = 1,4, 8, 11-tetrazaazaciclotetradecane) and [M(CN)(6)](3-) (M = Fe(III) and Mn(III)) give rise to cyano-bridged assemblies with 1D linear chain and 2D honeycomblike structures. The magnetic measurements on the 1D linear chain complex [Fe(cyclam)][Fe(CN)(6)].6H(2)O 1 points out its metamagnetic behavior, where the ferromagnetic interaction operates within the chain and the antiferromagnetic one between chains. The Neel temperature, T(N), is 5.5 K and the critical field at 2 K is 1 T. The unexpected ferromagnetic intrachain interaction can be rationalized on the basis of the axially elongated octahedral geometry of the low spin Fe(III) ion of the [Fe(cyclam)](3+) unit. The isostructural substitution of [Fe(CN)(6)](3-) by [Mn(CN)(6)](3-) in the previously reported complex [Ni(cyclam)](3)[Fe(CN)(6)](2).12H(2)O 2 leads to [Ni(cyclam)](3)[Mn(CN)(6)](2).16 H(2)O 3, which exhibits a corrugated 2D honeycomblike structure and a metamagnetic behavior with T(N) = 16 K and a critical field of 1 T. In the ferromagnetic phase (H > 1 T) this compound shows a very important coercitive field of 2900 G at 2 K. Compound [Ni(CTH)](3)[Fe(CN)(6)](2).13H(2)O 4, C(60)H(116)Fe(2)N(24)Ni(3)O(13), monoclinic, A 2/n, a = 20.462(7), b = 16.292(4), c = 27.262(7) A, beta = 101.29(4) degrees, Z = 4, also has a corrugated 2D honeycomblike structure and a ferromagnetic intralayer interaction, but, in contrast to 2 and 3, does not exhibit any magnetic ordering. This fact is likely due to the increase of the interlayer separation in this compound. ([Zn(cyclam)Fe(CN)(6)Zn(cyclam)] [Zn(cyclam)Fe(CN)(6)].22H(2)O.EtOH) 5, C(44)H(122)Fe(2)N(24)O(23)Zn(3), monoclinic, A 2/n, a = 14.5474(11), b = 37.056(2), c = 14.7173(13) A, beta = 93.94(1) degrees, Z = 4, presents an unique structure made of anionic linear chains containing alternating [Zn(cyclam)](2+) and [Fe(CN)(6)](3)(-) units and cationic trinuclear units [Zn(cyclam)Fe(CN)(6)Zn(cyclam)](+). Their magnetic properties agree well with those expected for two [Fe(CN)(6)](3-) units with spin-orbit coupling effect of the low spin iron(III) ions.     

A variable Ag-Cr-Oxalate channel lattice: [M(x)Ag(0.5)(-)(x)(H(2)O)(3)]@[Ag(2.5)Cr(C(2)O(4))(3)], M = K, Cs, Ag

Reaction of aqueous AgNO(3) with aqueous M(3)[Cr(ox)(3)] in >or=3:1 molar ratio causes the rapid growth of large, cherry-black, light-stable crystals which are not Ag(3)[Cr(ox)(3)], but [M(0.5)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)] (ox(2)(-) = oxalate, C(2)O(4)(2)(-); M = Na, K, Cs, Ag, or mixtures of Ag and a group 1 element). The structure of these crystals contains an invariant channeled framework, with composition [[Ag(2.5)Cr(ox)(3)](-)(0.5)]( infinity ), constructed with [Cr(ox)(3)] coordination units linked by Ag atoms through centrosymmetric [Cr-O(2)C(2)O(2)-Ag](2) double bridges. The framework composition [Ag(2.5)Cr(ox)(3)](-)(0.5) occurs because one Ag is located on a 2-fold axis. Within the channels there is a well-defined and ordered set of six water molecules, strongly hydrogen bonded to each other and some of the oxalate O atoms. This invariant channel plus water structure accommodates group 1 cations, and/or Ag cations, in different locations and in variable proportions, but always coordinated by channel water and some oxalate O atoms. The general formulation of these crystals is therefore [M(x)Ag(0.5-x)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)]. Five different crystals with this structure are reported, with compositions 1 Ag(0.5)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 2 Cs(0.19)Ag(0.31)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 3 K(0.28)Ag(0.22)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 4 Cs(0.41)Ag(0.09)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), and 5 Cs(0.43)Ag(0.07) [Ag(2.5)Cr(ox)(3)](H(2)O)(3). All crystallize in space group C2/c, with a approximately 18.4, b approximately 14.6, c approximately 12.3 A, beta approximately 113 degrees. Pure Ag(3)[Cr(ox)(3)](H(2)O)(3), which has the same crystal structure (1), was obtained from water by treating Li(3)[Cr(ox)(3)] with excess AgNO(3). Complete dehydration of all of these compounds occurs between 30 and 100 degrees C, with loss of diffraction, but rehydration by exposure to H(2)O(g) at ambient temperature leads to recovery of the original diffraction pattern. In single crystals, this reversible dehydration-hydration occurs without visually evident crystal change, but with loss of mechanical strength. We postulate a general mechanism for transport of water molecules along the channels, associated with local partial collapses of the channel framework, with concomitant bending but little breaking of the host Ag-O and Cr-O bonds, which is readily reversed.     

Tetranuclear complexes of [Fe(CO)2(C5H5)]+ with TCNX ligands (TCNX=TCNE, TCNQ, TCNB): intramolecular electron transfer alternatives in compounds (mu4-TCNX)[MLn]4

The complexes {(mu4-TCNX)[Fe(CO)2(C5H5)]4}(BF4)4 were prepared as light-sensitive materials from [Fe(CO)2(C5H5) (THF)](BF4) and the corresponding TCNX ligands (TCNE = tetracyanoethene, TCNQ=7,7,8,8-tetracyano-p-quinodimethane, TCNB=1,2,4,5-tetracyanobenzene). Whereas the TCNE and TCNQ complexes are extremely easily reduced species with reduction potentials>+0.3 V vs ferrocenium/ferrocene, the tetranuclear complex of TCNB exhibits a significantly more negative reduction potential at about -1.0 V. Even for the complexes with strongly pi-accepting TCNE and TCNQ, the very positive reduction potentials, the unusually high nitrile stretching frequencies>2235 cm(-1), and the high-energy charge-transfer transitions indicate negligible metal-to-ligand electron transfer in the ground state, corresponding to a largely unperturbed (TCNX degrees)(FeII)4 formulation of oxidation states as caused by orthogonality between the metal-centered HOMO and the pi* LUMO of TCNX. M?ssbauer spectroscopy confirms the low-spin iron(II) state, and DFT calculations suggest coplanar TCNE and TCNQ bridging ligands in the complex tetracations. One-electron reduction to the 3+ forms of the TCNE and TCNQ complexes produces EPR spectra which confirm the predominant ligand character of the then singly occupied MO through isotropic g values slightly below 2, in addition to a negligible g anisotropy of frozen solutions at frequencies up to 285 GHz and also through an unusually well-resolved solution X band EPR spectrum of {(mu4-TCNE)[Fe(CO)2(C5H5)]4}3+ which shows the presence of four equivalent [Fe(CO)2(C5H5)]+ moieties through 57Fe and 13C(CO) hyperfine coupling in nonenriched material. DFT calculations reproduce the experimental EPR data. A survey of discrete TCNE and TCNQ complexes [(mu4-TCNX)(MLn)4] exhibits a dichotomy between the systems {(mu4-TCNX)[Fe(CO)2(C5H5)]4}4+ and {(mu4-TCNQ)[Re(CO)3(bpy)]4}4+ with their negligible metal-to-ligand electron transfer and several other compounds of TCNE or TCNQ with Mn, Ru, Os, or Cu complex fragments which display evidence for a strong such interaction, i.e., an appreciable value delta in the formulation {(mu4-TCNXdelta-)[Mx+delta/4Ln]4}. Irreversibility of the first reduction of {(mu4-TCNB)[Fe(CO)2(C5H5)]4}(BF4)4 precluded spectroelectrochemical studies; however, the high-energy CN stretching frequencies and charge transfer absorptions of that TCNB analogue also confirm the exceptional position of the complexes {(mu4-TCNX)[Fe(CO)2(C5H5)]4}(BF4)4.     

Solvent-enhanced magnetic ordering temperature for mixed-valent chromium hexacyanovanadate(II), Cr(II)0.5Cr(III)[V(II)(CN)6].zMeCN, magnetic materials

The reaction of V(III)(THF)3Cl3 with NEt(4)CN in acetonitrile (MeCN) forms (NEt4)3[V(III)(CN)6].4MeCN (1), which after characterization was used as a molecular building block toward the synthesis of Prussian blue structured magnets. The reaction of 1 with [Cr(II)(NCMe)4](BF4)2 forms Cr(II)(0.5)Cr(III)[V(II)(CN)6].zMeCN via internal electron transfer, whose structure and magnetic properties are dependent on the degree of solvation, z. When solvated, Cr(II)(0.5)Cr(III)[V(II)(CN)6].1.2MeCN (2) is a mixture of crystalline and amorphous fractions that yield a material with two magnetic phases: bulk ferrimagnetic phase/crystalline [faced-centered-cubic lattice with a = 10.55(2) A] and cluster-glass phase/amorphous. The bulk ferrimagnetic phase exhibits a critical temperature, Tc, of 110 K, while the amorphous cluster-glass phase exhibits a freezing temperature, Tf, of approximately 25 K. Amorphous Cr(II)(0.5)Cr(III)[V(II)(CN)6].0.1MeCN (3) was determined to be the pure cluster-glass phase. This is an overall enhancement of 85 K (350%) in the magnetic ordering temperature via solvation, z. The coercivity was also increased 4-fold from 890 (2) and 3900 Oe (3) via desolvation.     

Synthesis, Structure, and Reactivities of [eta(2)-P(7)M(CO)(4)](3)(-), [eta(2)-HP(7)M(CO)(4)](2)(-), and [eta(2)-RP(7)M(CO)(4)](2)(-) Zintl Ion Complexes Where M = Mo, W

Ethylenediamine (en) solutions of [eta(4)-P(7)M(CO)(3)](3)(-) ions [M = W (1a), Mo (1b)] react under one atmosphere of CO to form microcrystalline yellow powders of [eta(2)-P(7)M(CO)(4)](3)(-) complexes [M = W (4a), Mo (4b)]. Compounds 4 are unstable, losing CO to re-form 1, but are highly nucleophilic and basic. They are protonated with methanol in en solvent giving [eta(2)-HP(7)M(CO)(4)](2)(-) ions (5) and are alkylated with R(4)N(+) salts in en solutions to give [eta(2)-RP(7)M(CO)(4)](2)(-) complexes (6) in good yields (R = alkyl). Compounds 5 and 6 can also be prepared by carbonylations of the [eta(4)-HP(7)M(CO)(3)](2)(-) (3) and [eta(4)-RP(7)M(CO)(3)](2)(-) (2) precursors, respectively. The carbonylations of 1-3 to form 4-6 require a change from eta(4)- to eta(2)-coordination of the P(7) cages in order to maintain 18-electron configurations at the metal centers. Comparative protonation/deprotonation studies show 4 to be more basic than 1. The compounds were characterized by IR and (1)H, (13)C, and (31)P NMR spectroscopic studies and microanalysis where appropriate. The [K(2,2,2-crypt)](+) salts of 5 were characterized by single crystal X-ray diffraction. For 5, the M-P bonds are very long (2.71(1) ?, average). The P(7)(3)(-) cages of 5 are not displaced by dppe. The P(7) cages in 4-6 have nortricyclane-like structures in contrast to the norbornadiene-type geometries observed for 1-3. (31)P NMR spectroscopic studies for 5-6 show C(1) symmetry in solution (seven inequivalent phosphorus nuclei), consistent with the structural studies for 5, and C(s)() symmetry for 4 (five phosphorus nuclei in a 2:2:1:1:1 ratio). Crystallographic data for [K(2,2,2-crypt)](2)[eta(2)-HP(7)W(CO)(4)].en: monoclinic, space group C2/c, a = 23.067(20) ?, b = 12.6931(13) ?, c = 21.433(2) ?, beta = 90.758(7) degrees, V = 6274.9(10) ?(3), Z = 4, R(F) = 0.0573, R(w)(F(2)) = 0.1409. For [K(2,2,2-crypt)](2)[eta(2)-HP(7)Mo(CO)(4)].en: monoclinic, space group C2/c, a = 22.848(2) ?, b = 12.528(2) ?, c = 21.460(2) ?, beta = 91.412(12) degrees, V = 6140.9(12) ?(3), Z = 4, R(F) = 0.0681, R(w)(F(2)) = 0.1399.     

Kinetic origin of the chelate effect. Base hydrolysis, H-exchange reactivity, and structures of syn,anti-[Co(cyclen)(NH3)2]3+ and syn,anti-[Co(cyclen)(diamine)]3+ ions (diamine = H2N(CH2)2NH2, H2N(CH2)3NH2)

The synthesis of syn,anti-[Co(cyclen)en](ClO4)3 (1(ClO4)3) and syn,anti-[Co(cyclen)tn](ClO4)3 (2(ClO4)3) is reported, as are single-crystal X-ray structures for syn,anti-[Co(cyclen)(NH3)2](ClO4)3 (3(ClO4)3). 3(ClO4)3: orthorhombic, Pnma, a = 17.805(4) A, b = 12.123(3) A, c = 9.493(2) A, alpha = beta = gamma = 90 degrees, Z = 4, R1 = 0.030. 1(ClO4)3: monoclinic, P2(1)/n, a = 8.892(2) A, b = 15.285(3) A, c = 15.466(3) A, alpha = 90 degrees, beta = 91.05(3) degrees, gamma = 90 degrees, Z = 4, R1 = 0.0657. 2Br3: orthorhombic, Pca2(1) a = 14.170(4) A, b = 10.623(3) A, c = 12.362(4) A, alpha = beta = gamma = 90 degrees, Z = 4, R1 = 0.0289. Rate constants for H/D exchange (D2O, I = 1.0 M, NaClO4, 25 degrees C) of the syn and anti NH protons (rate law: kobs = ko + kH[OD-]) and the apical NH, and the NH3 and NH2 protons (rate law: kobs = kH[OD-]) in the 1, 2, and 3 cations are reported. Deprotonation constants (K = [Co(cyclen-H)(diamine)2+]/[Co(cyclen)(diamine)3+][OH-]) were determined for 1 (5.5 +/- 0.5 M-1) and 2 (28 +/- 3 M-1). In alkaline solution 1, 2, and 3 hydrolyze to [Co(cyclen)(OH)2]+ via [Co(cyclen)(amine)OH)]2+ monodentates. Hydrolysis of 3 is two step: kobs(1) = kOH(1)[OH-], kobs(2) = ko + kOH(2)[OH-] (kOH(1) = (2.2 +/- 0.4) x 10(4) M-1 s-1, ko = (5.1 +/- 1.2) x 10(-4) s-1, kOH(2) = 1.0 +/- 0.1 M-1 s-1). Hydrolysis of 2 is biphasic: kobs(1) = k1K[OH-]/(1 + K[OH-] (k1 = 5.0 +/- 0.2 s-1, K = 28 M-1), kobs(2) = k2K2[OH-]/(1 + K2[OH-]) (k2 = 3.5 +/- 1.2 s-1, K2 = 1.2 +/- 0.8 M-1). Hydrolysis of 1 is monophasic: kobs = k1k2KK2[OH-]2/(1 + K[OH-1])(k-1 + k2K2[OH-]) (k1 = 0.035 +/- 0.004 s-1, k-1 = 2.9 +/- 0.6 s-1, K = 5.5 M-1, k2K2 = 4.0 M-1 s-1). The much slower rate of chelate ring-opening in 1, compared to loss of NH3 from 3, is rationalized in terms of a reduced ability of the former system to allow the bond angle expansion required to produce the SN1CB trigonal bipyramidal intermediate.     

Two enantiomers of [Cu(3)(mnt)(3)](3-) as ligands to Cu(i) or Ag(i) in building [Cu(6)M(2)(mnt)(6)](4-) complexes (M = Cu or Ag) with the reversal of the reaction by X(-) (X = Cl, Br)

Two enantiomers of [Bu(4)N](3)[Cu(3)(mnt)(3)] () formed by Na(2)(mnt) (mnt = maleonitriledithiolate, [S(2)C(2)(CN)(2)](2-)) and CuCl in a 1 : 1 molar ratio react further with MCl (M = Cu or Ag) involving both the enantiomers of to produce the larger complex, [Bu(4)N](4)[Cu(6)M(2)(mnt)(6)] (M = Cu (2), Ag (3)) from which the capped Cu(+) or Ag(+) ion can readily be removed by Bu(4)NX (X = Cl, Br), reverting or back to . Such reversal does not work with non-coordinating anions like BF(4)(-), ClO(4)(-) and PF(6)(-).     

Chemistry of Thiobenzoates: Syntheses, Structures, and NMR Spectra of Salts of [M(SOCPh)(3)](-) (M = Zn, Cd, Hg)

The salts (Ph(4)E)[M(SOCPh)(3)] (M = Zn, Cd, or Hg; E = P or As) are produced by the reaction of Zn(NO(3))(2).6 H(2)O, Cd(NO(3))(2).4H(2)O or HgCl(2) with Et(3)NH(+)PhCOS(-) and (Ph(4)E)X (E = P, X = Br; E = As, X = Cl) in aqueous MeOH in the ratios M(II):PhCOS(-):Ph(4)E(+) = 1:>/=3:>/=1. The crystal structures of (Ph(4)P)[Zn(SOCPh)(3)] (1), (Ph(4)As)[Cd(SOCPh)(3)] (2) and (Ph(4)P)[Hg(SOCPh)(3)] (3) have been determined by single-crystal X-ray diffraction experiments. Crystal data for 1: triclinic; space group P&onemacr;; Z = 2; a = 10.819(2) ?, b = 13.219(3) ?, c = 15.951(3) ?; alpha = 101.75(2) degrees, beta = 97.92(1) degrees, gamma = 109.18(2) degrees. Crystal data for 2: triclinic; space group P&onemacr;; Z= 2; a = 10.741(2) ?, b = 13.168(2) ?, c = 15.809(2) ?; alpha = 101.00(1) degrees, beta = 97.65(1) degrees, gamma = 109.88(1) degrees. Crystal data for 3: monoclinic; space group P2(1)/n; Z = 4; a = 13.302(2) ?, b = 14.276(2) ?, c = 21.108(2) ?; beta = 90.92(1) degrees. The compounds 1 and 2 are isomorphous and isostructural. In the anions [M(SOCPh)(3)](-) the metal atoms have trigonal planar coordination by three sulfur atoms. The metal atoms are further more weakly coordinated intramolecularly to one (M = Hg) or two (M = Zn, Cd) thiobenzoate oxygen atom(s). Using the Bond Valence approach it is found that the contribution of M.O bonding to the total bonding is in the order Cd > Zn > Hg. The metal ((113)Cd, (199)Hg) NMR signals of [M(SOCPh)(3)](-) (M = Cd, Hg) are more shielded than those found for MS(3) kernels in thiolate complexes, a difference attributed to the M(.)O bonding in the thiobenzoate complexes. The (113)Cd resonance of [Cd(SOCPh)(3)](-) in dilute solution is in the region anticipated from dilution data for [Na(Cd{SOCPh}(3))(2)](-).     

Synthesis, Characterization, and Comparative Properties of [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] and [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)

The reaction of [PPN](2)[Re(6)C(CO)(19)] with Mo(CO)(6) and Ru(3)(CO)(12) under sunlamp irradiation provided the new mixed-metal clusters [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] and [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)], which were isolated in yields of 85% and 61%, respectively. The compound [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] crystallizes in the monoclinic space group P2(1)/c with a = 20.190 (7) ?, b = 16.489 (7) ?, c = 27.778 (7) ?, beta = 101.48 (2) degrees, and Z = 4 (at T = -75 degrees C). The cluster anion is composed of a Re(6)C octahedral core with a face capped by a Mo(CO)(4) fragment. There are three terminal carbonyl ligands coordinated to each rhenium atom. The four carbonyl ligands on the molybdenum center are essentially terminal, with one pair of carbonyl ligands (C72-O72 and C74-O74) subtending a relatively large angle at molybdenum (C72-Mo-C74 = 147.2(9) degrees ), whereas the remaining pair of carbonyl ligands (C71-O71 and C73-O73) subtend a much smaller angle (C71-Mo-C73 = 100.5(9) degrees ). The (13)C NMR spectrum of (13)CO-enriched [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] shows signals for four sets of carbonyl ligands at -40 degrees C, consistent with the solid state structure, but the carbonyl ligands undergo complete scrambling at ambient temperature. The (13)C NMR spectrum of (13)CO-enriched [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)] at 20 degrees C is consistent with the expected structure of an octahedral Re(6)C(CO)(18) core capped by a Ru(CO)(3) fragment. The visible spectrum of [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] shows a broad, strong band at 670 nm (epsilon = 8100), whereas all of the absorptions of [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)] are at higher energy. An irreversible oxidation wave with E(p) at 0.34 V is observed for [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)], whereas two quasi-reversible oxidation waves with E(1/2) values of 0.21 and 0.61 V (vs Ag/AgCl) are observed for [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)]. The molybdenum cap in [Re(6)C(CO)(18)Mo(CO(4))](2-) is cleaved by heating in donor solvents, and by treatment with H(2), to give largely [H(2)Re(6)C(CO)(18)](2-). In contrast, [Re(6)C(CO)(18)Ru(CO)(3)](2-) shows no tendency to react under similar conditions.     

Mn(III)(tetra-biphenyl-porphyrin)-TCNE single-chain magnet via suppression of the interchain interactions

A single-chain magnet (SCM) of [Mn(TBPP)(TCNE)]·4m-PhCl(2) (1), where TBPP(2-) = meso-tetra(4-biphenyl)porphyrinate; TCNE(?-) = tetracyanoethenide radical anion; m-PhCl(2) = meta-dichlorobenzene, was prepared via suppression of interchain interactions. 1 has a one-dimensional alternating Mn(III)(porphrin)-TCNE(?-)chain structure similar to those of a family of complexes reported by Miller and co-workers. From a comparison of the static magnetic properties of 1 with other Mn(III)(porphyrin)-TCNE(?-) chains, a magneto-structural correlation between the intrachain magnetic exchange and both the dihedral angle between the mean plane on [Mn(TBPP)(TCNE)] and Mn-N≡C was observed. The ac magnetic susceptibility data of 1 could be fit with the Arrhenius law, indicating that slow magnetic relaxation and ruling out three-dimensional long-range ordering and spin-glass-like behavior. The Cole-Cole plot for 1 was semicircular, verifying that it is an SCM. Therefore, 1 is an ideal single-chain magnet with significantly strong intrachain magnetic exchange interactions beyond the Ising limit.     

Dinuclear [Co(II)(NCMe)5Co(II)(NCS)4] possessing octahedral and tetrahedral Co(II) sites

The structural and magnetic properties of dinuclear [Co(II)(NCMe)(5)Co(II)(NCS)(4)]·MeCN have been investigated. The structure consists of an octahedral Co(II)(NCMe)(5) center connected to a tetrahedral Co(II)(NCS)(4) center bridged by a μ(1,3)-NCS(-) ligand. The bridging NCS(-) weakly couples the pair of S = (3)/(2) Co(II) spin sites, as evidenced by the magnetic data being best fit by the Curie-Weiss expression with θ = -15.5 K.