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Synteza i właściwości spektroskopowe oraz elektrochemiczne hydrokso(izopropokso)-[tris(3,5-dimetylopirazol-1-ilo)borano]-nitrozylmolibdenu(II)

Romańczyk P., Lubera T., Włodarczyk A.

Czasopismo Techniczne. Chemia

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2010

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R. 107, z. 1-Ch

285-290

PL

W artykule opisano syntezę mieszanego hydrokso(izopropokso) kompleksu [tris(3,5-dimetylopirazol-1-ilo)borano]nitrozylmolibdenu(n), [Mo(NO)(Tp[^Me2])(OH)(OPr[^i])] i przedstawiono jego pełną charakterystykę spektroskopową oraz elektrochemiczną.

EN

The paper presents the synthesis of a mixed hydroxo(isopropoxo) complex of [tris(3,5-dimethylpyrazol-1-yl)borato ]nitrosylmolybdenum(n), [Mo(NO)(Tp[^Me2])(OH)(OPr[^i])], which has been fully characterised spectroscopically and electrochemically.

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Oddziaływania elektronowe w dwucentrowych kompleksach nitrozylowych molibdenu

Włodarczyk A., Romańczyk P.

Wiadomości Chemiczne

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2008

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[Z] 62, 3-4

187-208

EN

Design and synthesis of redox active binuclear complexes in which metal centres are linked via bridging ligands enabling electronic and magnetic interactions between them are crucial for an understanding of key processes in chemistry and biology. In biological systems, such as proteins, electron transfer involves a charge transport over a considerable distance (>10 A*) [8-11,13-19]. On the other hand, long range electronic interactions are central in the development of potential elements for molecular electronics like molecule-sized wires, diodes, light activated switches, transistors (Fig. 1), logic gates etc. [1-7]. This article reviews some of the work performed in the area of bimetallic nitrosyl molybdenum complexes containing tris(3,5-dimethylpyrazol-1-yl)hydroborato ligand (Fig. 4). Numerous examples of mixed-valence species have been described, showing a wide range of behaviour from fully delocalized to valence-trapped systems of which electrochemical (voltammetry, Fig. 3), spectroscopic (EPR (Fig. 5), IR and UV-Vis/NIR spectroscopy) and magnetic susceptibility were studied. These results are summarised in Table 1. Many such complexes show exceptionally strong electrochemical (?Ef) and magnetic exchange interactions (J) between metal centres depending on the features of the bridging ligand such as length, degree of conjugation, dihedral angles between aromatic rings, substitution pattern, and symmetry [28, 41]. For example, in [{Mo(NO)(TpMe2)Cl}2{4,4'-bipy}] (Fig. 9) ?Ef equals 765 mV, being an order of magnitude greater when compared to the {Ru(NH3)5}2+/3+ analogue, and J = -33 cm-1 [43, 68, 69]. Using 3,3'-dimethyl-4,4'-bipy as a bridge forces a twist between the two pyridyl rings and decreases both ?Ef and J down to 380 mV and 3.5 cm-1, respectively [42, 71]. The introduction of a saturated section into the bridge, which breaks the conjugation, e.g. in 1,2-bis(4-pyridyl)ethane ligand, considerably decreases ?Ef (105 mV) but does not exclude electronic and magnetic through-bridge interactions [43]. Recently a series of bimetallic complexes based on {Mo(NO)(TpMe2)}2+ centres comprising n-alkanediolate bridges (Fig. 12) have been prepared. These species exhibited intermediate metal-metal interactions (310 mV in ethane-1,2-diolate) [54, 55] which prompted investigation of electronic interactions through saturated alkyl chains by DFT [64].

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Synteza i właściwości elektrochemiczne biskrezolanowych kompleksów nitrozylowych molibdenu

Włodarczyk A., Romańczyk P., Lubera T.

Czasopismo Techniczne. Chemia

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2008

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R. 105, z. 1-Ch

165-170

PL

Otrzymano i scharakteryzowano spektroskopowo i elektrochemicznie nowe biskrezolanowe kompleksy nitrozylowe molibdenu [Mo(NO){HB(3,5-Me[2]C[3]N[2]H)[3]}(OR)[2]] (R = C[6]H[4]Me-m lub C[6]H[4]Me-p). W woltamogramach obserwowano jeden odwracalny (izomer para) lub quasi-odwracalny (izomer meta) proces jednoelektronowej redukcji przy E[1/2] [równe w przybliżeniu] -1,32 V vs Fc. Badane kompleksy ulegają redukcji trudniej (przesunięcie katodowe ponad 100 mV) w porównaniu z [Mo(NO){HB(3,5-Me[2]C[3]N[2]H)[3]}(OPh)[2]], co odzwierciedla wpływ aktywacji pierścieni fenylowych przez grupy metylowe.

EN

New biscresolato molybdenum nitrosyl complexes Me[2]C[3]N[2]H)[3]}(OR)[2]] (R = C[6]H[4]Me-m or C[6]H[4]Me-p) have been synthesised and characterised spectroscopically and electrochemically. In their voltammograms one reversible (isomer para) or quasi-reversible (isomer meta) one-electron processes at E[1/2] [is approximately equal to] -1.32 V vs Fc were observed. The investigated complexes are harder to reduce (cathodic shift greater than 100 mV) than [Mo(NO){HB(3,5-Me[2]C[3]N[2]H)[3]}(OPh)[2]], which reflects the influence of activation of phenyl rings by methyl groups. @eng

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Elektrochemiczne właściwości nitrozylowych kompleksów molibdenu zawierających ligandy propoksylanowe. Struktura krystaliczna [Mo(NO){HB(3,5-Me[2]C[3]N[2]H)[3]}Cl(OPr[^i])]

Włodarczyk A., Romańczyk P., Lubera T., Nitek W.

Czasopismo Techniczne. Chemia

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2008

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R. 105, z. 1-Ch

155-164

PL

Otrzymano i scharakteryzowano elektrochemicznie nitrozylowe kompleksy molibdenu zawierające ligandy propoksylanowe [Mo(NO){HB(3,5-Me[2]C[3]N[2]H)[3]}X(Y)] (X = Cl, Y = OPr[^i] (1); X = Y = OPr[^i] (2) lub OPr[^n] (3)). Związek 1 ulega redukcji odwracalnie (E[1/2] = -1,32 V vs Fc), 3 - quasi-odwracalnie (E[1/2] = -1,92 V), natomiast 2 nieodwracalnie (E[1/2] = -2,22 V). Dla symetrycznie podstawionych kompleksów obserwowano także quasi-odwracalne procesy anodowe. Wyznaczono strukturę molekularną kompleksu [Mo(NO){HB(3,5-Me[2]C[3]N[2]H)[3]}Cl(OPr[^i])]. Związek ten krystalizuje w układzie trójskośnym, w grupie przestrzennej P-1 (a = 10,038(5) A, b = 10,144(5) A, c = 13,964(5) A, [alfa] = 71,997(5)[stopni], [beta] = 86,033(5)[stopni], [gamma] = 62,273(5)[stopni], Z = 2).

EN

Molybdenum nitrosyl complexes incorporating propoxylate ligands [Mo(NO){HB(3,5- -Me[2]C[3]N[2]H)[3]}X(Y)] (X = Cl, Y = OPr[^i] (1); X = Y = OPr[^i] (2) or OPrn (3)) have been synthesised and characterised electrochemically. Compound 1 undergoes reversible reduction (E[1/2] = -1.32 V vs Fc), 3 - quasi-reversible reduction (E[1/2] = -1.92 V), whereas 2 is reduced irreversibly (E[1/2] = -2.22 V). In the case of symmetrically substituted species quasi-reversible anodic processes were also observed. The molecular structure of [Mo(NO){HB(3,5-Me[2]C[3]N[2]H)[3]}Cl(OPr[^i])] has been determined. The compound crystallises in the triclinic system, space group P-1 (a = 10.038(5) A, b = 10.144(5) A, c = 13.964(5) A, [alfa] = 71.997(5)[degrees], [beta] = 86.033(5)[degrees], [gamma] = 62.273(5)[degrees], Z = 2).