Magnetic Interaction in Dinuclear Triphos−Cobalt Complexes with Co···Co Separations of 8 and 10 Å

Abstract

Weak antiferromagnetic exchange interactions are observed in two CoII dimers of the general formula [{(triphos)Co}2(μ‐dicarboxylato)](BF4)2 where the dicarboxylate is the dianion of fumaric acid [3 ·(BF4)2] or terephthalic acid [4 ·(BF4)2] and triphos is the tridentate phosphorus ligand 1,1,1‐tris(diphenylphosphanomethyl)ethane. In these complexes the metal ions are separated by 8 and 10 Å, as determined by X‐ray crystallography. Insight into the interaction pathway is gained through molecular orbital calculations performed on model compounds. The influence of bridging‐ligand distortions and the stereochemistry around the two cobalt centres is discussed.

Tuning the Energy of the NIR Absorption of Dinuclear Triphos-Cobalt-Complexes

“…Recent research has shown that dinuclear complexes based on the triphos-cobalt fragment [triphos = l,l,l-tris(diphenylphosphanomethyl)ethane] as building block exhibit antiferro magnetic exchange interactions between the two d7 low-spin Co(II) centers, e.g. in chloro [2], 1,4,5,8-tetraoxonaphthalino [3] or dicarboxylato bridged triphos-Co(II) complexes [4], The diamagnetic /_i-anilato d6 low-spin Co(III) complexes [(triphos)Co-(C6X20 4 )Co(triphos)]2+ (X = H, Cl, Br, I, N 0 2, Me, /Pr, Ph) [5] absorb stronly in the near infrared re gion (Amax = 1132 -1201 nm; emdX = 17110 -58300 M~1 cm -1) which has been interpreted as being due to a ligand-to-metal charge transfer. For these com plexes the energy of the NIR absorption depends slightly on the substituent X at the bridging arene ligand.…”

“…2,4, To a solution of the triphos ligand (624 mg, 1 mmol) in THF (15 ml) a solution of Co(BF4)2 • 6 H2O (341 mg, 1 mmol) in ethanol (15 ml) was added. Addition of the co-ligand [1 (BF4)2 : 69 mg, 2 (BF4)2: 103 mg, 3 a(BF4)2: 69 mg, 3b(BF4)2: 104 mg, 3 c(BF4)2: 148 mg, 3 d(BF4)2: 195 mg, 4 (BF4)2: 83 mg, 5(BF4)2: 85 mg, 6 (BF4)2: 87 mg, 0.5 mmol] to the orange-red colored solution caused an immediate colour change (22+: green, 42+: violet, else blue).…”

trans-Diaquabis(thiosemicarbazido-κ2N,S)nickel(II) dimaleate dihydrate

“…In the latter methodology, the hydrogen bond can in¯uence the metal coordination geometry and adjust the structure of relative compounds because of the bond's relative strength, directionality,¯exibility and dynamic character (Allen et al, 1999;Russell et al, 1997). The chemistry of metal complexes containing S,N-bidentate ligands has been studied widely because of the structural features and particular properties of these complexes (Fun et al, 1996;West et al, 1993); dicarboxylates are an important class of ligands in the formation of coordination polymers (Heinze et al, 1998;Groeneman et al, 1999). As part of our studies of the synthesis and characterization of potential non-linear optical materials, we report here the crystal structure of the title compound, (I).…”

Complexes of selected transition metal ions with 4-oxo-4-{[3-(trifluoromethyl)phenyl]amino}but-2-enoic acid: Synthesis, structure and magnetic properties

“…They also show a strong antifungal activity [16] or they may act as inhibitors against aldose reductase [17]. The complexes of Tl(I), Sn(IV), Mo(IV) and Co(II) ions with maleinic acid and the compounds of Cu(II) ion with its various amido derivatives were prepared and characterized [18][19][20][21][22][23][24]. The thermodynamics functions for the formation of complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) ions with maleanilic, 4-nitro-and 4-methoxymaleanilic acids were determined [25].…”