Reformulation from x-ray crystallography of a dinuclear thiocyanate complex of rhenium. The first observation of solely N-bonded, bridging thiocyanate

Cotton, F. Albert; Davison, Alan; Ilsley, William H.; Trop, Harvey S.

doi:10.1021/ic50200a018

Cited by 37 publications

(21 citation statements)

References 3 publications

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“…These assignments are consistent with Nand S-bound NCSmoieties observed for other transition metal complexes. 30 The CtN stretch observed for the N-bound linkage isomers is in the range observed for other Tc [31][32][33][34][35] and Re [36][37][38][39][40][41][42][43] isothiocyanate complexes.…”

Section: Resultsmentioning

confidence: 58%

Linkage Isomerization of MSCN(CDOH)₂(CDO)BMe to MNCS(CDOH)₂(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)₂(CDO)BMe, ReNCS(CDOH)₂(CDO)BMe, and ReSCN(CDOH)₂(CDO)BMe

et al. 1998

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The 7-coordinate technetium(III) and rhenium(III) monocapped tris(dioxime) complexes [MX(dioxime) 3 BR] have been prepared in which the seventh ligand, X, is thiocyanate or hydroxide (M ) Tc, Re; R ) Me, Et). Both the N-and S-bound thiocyanate linkage isomers are produced during the syntheses, however, the S-bound complex isomerizes to the N-bound analogue. The synthetic routes employed allowed isolation of sufficient quantities of the technetium and rhenium S-bound isomers to be identified; however, full characterization was not possible. The linkage isomerization reaction of TcSCN(CDOH) 2 (CDO)BMe to TcNCS(CDOH) 2 (CDO)BMe was monitored in dichloromethane by UV-visible spectrophotometry, with four isosbestic points observed, consistent with the formation of a single product. The N-bound isomers for both Tc and Re, and the S-bound isomer of Re were characterized by single-crystal X-ray diffraction analysis. The two N-bound complexes were found to be isostructural. TcNCS(CDOH) 2 (CDO)BMe crystallized in the orthorhombic space group P2 1 2 1 2 1 with a ) 15.814-(2) Å, b ) 17.855(3) Å, c ) 17.997(5) Å, Z ) 8, R ) 0.054, and R W ) 0.057. ReNCS(CDOH) 2 (CDO)BMe crystallized in the orthorhombic space group P2 1 2 1 2 1 with a ) 15.795(1) Å, b ) 17.843(2) Å, c ) 18.014(3) Å, Z ) 8, R ) 0.054, and R W ) 0.073. In both cases two independent molecules per unit cell were observed. ReSCN(CDOH) 2 (CDO)BMe crystallized in the monoclinic space group P2 1 /c with a ) 10.0866(6) Å, b ) 26.301-(2) Å, c ) 12.4592(7) Å, β ) 100.5(1) deg, Z ) 4, R ) 0.100, and R W ) 0.141.

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Section: Resultsmentioning

confidence: 58%

Linkage Isomerization of MSCN(CDOH)₂(CDO)BMe to MNCS(CDOH)₂(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)₂(CDO)BMe, ReNCS(CDOH)₂(CDO)BMe, and ReSCN(CDOH)₂(CDO)BMe

et al. 1998

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“…A zero-field splitting of this order is to be expected from a purely dipolar interaction at the likely internuclear distance of 7-8 A for a pair of Cu" ions oriented at an angle of ca. 45-50' to the field direction (considered 90" to the CUN, planes), according to equation (1)' On the basis of D,, = 0.75 g2p2(1 -3 cos2 8)/r,, 3 the structure determination which follows, the values for 8 and r l , from (1) seem to present a reasonable approximation to the geometry in this series of Cu" dimers.…”

Section: Resultsmentioning

confidence: 96%

Dicopper(II) complexes of a 28-membered N8 macrocycle. Evidence for proton transfer from co-ordinated secondary amine to thiocyanate, leading to formation of an lsothiocyanic acid complex

Drew¹,

Murphy²,

Nelson³

et al. 1987

J. Chem. Soc., Dalton Trans.

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Schiff-base template condensation of 2,6-diacetylpyridine with the diamine 3,3'-diaminodipropylamine on Ag+, Pb2+, Ca2+, or Sr2+ led to binuclear Ag+ and Pb2+ and mononuclear Ca2+ and Sr2+ complexes of the 28-membered ligand H,L. A series of binuclear C u t ' complexes of this macrocycle, including [Cu,( H,L) (NCS),], were prepared by transmetallation in acetonitrile solution. A complex of formula Cu2(HL)(BPh,),*2MeCN was prepared from [Sr(H,L)] [BPh,], and Cu(O,CMe), in the presence of excess NaBPh,. This cation was characterised by e.s.r. as a dicopper(i1) complex of the singly deprotonated ligand H L-. The complex [Cu,( L) ( H NCS),] [BPh4],.l.5MeCN was prepared, which showed Vasym( NCS) at 1 992 cm-', characteristic of bridging thiocyanate. A single-crystal X-ray structure determination was carried out. Crystals were triclinic, space group P i with a = 14.695( 11), b = 1 4 . 0 5 1 ( 1 1 ) , c = 2 0 . 7 2 1 ( 1 1 ) ~, a = 111.5(1),p=98.8(1),y= 100.3(1)",andZ= 2 . 3 9 6 9 Independent reflections above background have been measured on a diffractometer and the structure refined to R = 0.089. The unit cell contains t w o independent cations both with imposed 7 symmetry, four BPh,-anions and solvent molecules. In both cations the Cu Cu distance is 7.25 A. Each copper atom is bonded to four nitrogen atoms of the macrocycle and nitrogen of a terminal thiocyanate. The Cu-N-C(S) angles were unusually small at lOO(2) and 109(2)". We believe that the explanation for the correlated phenomenon of small CU-N-C angle and a low value for the Vasym( NCS) absorption is that proton transfer has occurred from the co-ordinated NH group to the NCS ion, making this a complex of thiocyanic acid with the macrocyclic ligand being in the doubly deprotonated form L2-.Recently we have investigated' a number of binuclear Cu" complexes where, because of proximity of the paramagnetic centres or intermediacy of a bridging ligand, strong interaction exists between the Cu" centres. This present work describes binuclear Cu" complexes with the macrocycle H,L (and deprotonated forms) and the hydrogenated ligand L' (H,L + 8 H), where the internuclear distance is long and bridging ligands are absent (Figure 1).Intriguingly, in one instance preliminary i.r. spectroscopic data implied the existence of a single-atom thiocyanate bridge, but X-ray crystallographic structural investigations did not confirm this, suggesting instead formation of an isothiocyanic acid complex.Isothiocyanic acid (HCNS), being a strong acid of pK, ca. -1.8, is not expected to co-ordinate to metal ions as the neutral (unionised) acid, although protonation of N-co-ordinated NCSin Co"' complexes in highly acidic media has been suggested.2 The thiocyanate ion (NCS)-, on the other hand, is a well known ambidentate ligand capable of co-ordinating in the variety of modes, (a)--(e). A distinctive property of bridging mode (e) is the occurrence of the thiocyanate asymmetric stretch, v,,,,(NCS), below 2000 cm-' in the i.r. When a presumed dithiocyanato complex of the ligand under study ...

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“…The IR spectrum of [Re 2 (NCS) 10 ] 3- consists of two bands at 2078 and 2058 cm -1 , assigned to ν CN of terminal NCS - , and two others at 1922 and 1885 cm -1 , assigned to ν CN of the solely N-bound bridging NCS - . On oxidation the ν CN bands moved to lower wavenumber and on reduction to higher wavenumber …”

Section: Resultsmentioning

confidence: 99%

Redox Behavior of Edge-Shared Bioctahedral [Re₂(μ-NCS)₂(NCS)₈]³^-and Its Relationship to the Direct Metal−Metal-Bonded Ion [Re₂(NCS)₈]²^-: A Spectroelectrochemical Study

Clark

Humphrey

1996

Inorg. Chem.

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Electrochemical and spectroelectrochemical studies have shown that the edge-shared bioctahedral [Re2(μ-NCS)2(NCS)8]3- anion can be reversibly oxidized and reduced (in one-electron steps) with retention of structure to give the even electron species [Re2(μ-NCS)2(NCS)8]2- and [Re2(μ-NCS)2(NCS)8]4-. A second oxidation of [Re2(μ-NCS)2(NCS)8]3- is however only partially reversible, the [Re2(μ-NCS)2(NCS)8]1- ion being of limited stability. Further irreversible oxidation of this latter species can be achieved in what appears to be a ligand-based process yielding cyanide-containing species. An irreversible two-electron reduction of [Re2(μ-NCS)2(NCS)8]4- culminates in structural rearrangement to the direct metal−metal-bonded ion [Re2(NCS)8(NCS)2]6-, as shown by voltammetric and spectroelectrochemical measurements. Re-oxidation of [Re2(NCS)8(NCS)2]6- results in the quantitative re-formation of the edge-shared structure [Re2(μ-NCS)2(NCS)8]4-. This reversible structural interconversion occurs in both noncoordinating and coordinating solvents, as well as in the presence of a high concentration of free Cl-. The redox behavior of [Re2(NCS)8]2- has also been reinvestigated, and the relationship between the direct metal−metal-bonded and edge-shared bioctahedral structures established. Oxidation of [Re2(NCS)8]2- at room temperature results in the formation of [Re2(μ-NCS)2(NCS)8]2- and NCS--depleted products. [Re2(NCS)8]2- reacts immediately with 2 mol equiv of NCS- to give [Re2(μ-NCS)2(NCS)8]4-, which is susceptible to aerial oxidation. At low temperature, however, the one-electron oxidation and reduction of [Re2(NCS)8]2- become reversible on the time scale of the IR spectroelectrochemical experiment, such that [Re2(NCS)8]1- and [Re2(NCS)8]3- have been characterized in situ. Further reduction of [Re2(NCS)8]3- to [Re2(NCS)8]4- is partially reversible under these conditions thus permitting characterization of the latter species.

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Reformulation from x-ray crystallography of a dinuclear thiocyanate complex of rhenium. The first observation of solely N-bonded, bridging thiocyanate

Cited by 37 publications

References 3 publications

Linkage Isomerization of MSCN(CDOH)₂(CDO)BMe to MNCS(CDOH)₂(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)₂(CDO)BMe, ReNCS(CDOH)₂(CDO)BMe, and ReSCN(CDOH)₂(CDO)BMe

Linkage Isomerization of MSCN(CDOH)₂(CDO)BMe to MNCS(CDOH)₂(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)₂(CDO)BMe, ReNCS(CDOH)₂(CDO)BMe, and ReSCN(CDOH)₂(CDO)BMe

Dicopper(II) complexes of a 28-membered N8 macrocycle. Evidence for proton transfer from co-ordinated secondary amine to thiocyanate, leading to formation of an lsothiocyanic acid complex

Redox Behavior of Edge-Shared Bioctahedral [Re₂(μ-NCS)₂(NCS)₈]³^-and Its Relationship to the Direct Metal−Metal-Bonded Ion [Re₂(NCS)₈]²^-: A Spectroelectrochemical Study

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Reformulation from x-ray crystallography of a dinuclear thiocyanate complex of rhenium. The first observation of solely N-bonded, bridging thiocyanate

Cited by 37 publications

References 3 publications

Linkage Isomerization of MSCN(CDOH)2(CDO)BMe to MNCS(CDOH)2(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)2(CDO)BMe, ReNCS(CDOH)2(CDO)BMe, and ReSCN(CDOH)2(CDO)BMe

Linkage Isomerization of MSCN(CDOH)2(CDO)BMe to MNCS(CDOH)2(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)2(CDO)BMe, ReNCS(CDOH)2(CDO)BMe, and ReSCN(CDOH)2(CDO)BMe

Dicopper(II) complexes of a 28-membered N8 macrocycle. Evidence for proton transfer from co-ordinated secondary amine to thiocyanate, leading to formation of an lsothiocyanic acid complex

Redox Behavior of Edge-Shared Bioctahedral [Re2(μ-NCS)2(NCS)8]3-and Its Relationship to the Direct Metal−Metal-Bonded Ion [Re2(NCS)8]2-: A Spectroelectrochemical Study

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Linkage Isomerization of MSCN(CDOH)₂(CDO)BMe to MNCS(CDOH)₂(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)₂(CDO)BMe, ReNCS(CDOH)₂(CDO)BMe, and ReSCN(CDOH)₂(CDO)BMe

Linkage Isomerization of MSCN(CDOH)₂(CDO)BMe to MNCS(CDOH)₂(CDO)BMe (M = Tc, Re). Crystal Structures of TcNCS(CDOH)₂(CDO)BMe, ReNCS(CDOH)₂(CDO)BMe, and ReSCN(CDOH)₂(CDO)BMe

Redox Behavior of Edge-Shared Bioctahedral [Re₂(μ-NCS)₂(NCS)₈]³^-and Its Relationship to the Direct Metal−Metal-Bonded Ion [Re₂(NCS)₈]²^-: A Spectroelectrochemical Study