The preparation and properties of a new pentacyanomanganesenitric oxide anion, [Mn(CN)5NO]2−, and some observations on other pentacyanonitrosyl complexes

Cotton, F. Albert; Monchamp, R. R.; Henry, R.J.M.; Young, Ralph C.

doi:10.1016/0022-1902(59)80183-4

Cited by 84 publications

(7 citation statements)

References 8 publications

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“…In the case of {Mn−NO} 6 nitrosyls, an almost linear Mn−N−O bond and ν NO in the range 1700−1750 cm -1 are considered as strong evidence for a {low-spin Mn(I)−NO + } formulation. This formulation has its origin in the organometallic species [Mn(CN) 5 (NO)] 3- , which exhibits ν NO at 1725 cm -1 . What is ignored here is the fact that organometallic species such as [Mn(PR 3 )X 2 (NO)] (X = Cl - , Br - ) exhibit ν NO in the range 1595−1607 cm -1 and have been assigned a {Mn(III)−NO - } formulation .…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, the Mn−N−O angles in all these species are within the narrow range of 174−180°, and hence, assignment of NO + over NO • or NO - on the basis of the Mn−N−O bond angle is not very convincing. On the other hand, the N−O stretching frequency (ν NO ) appears to be quite sensitive to the assignment since [Mn(NO)(TC-5,5)] exhibits ν NO at 1662 cm -1 while [Mn(TPP)(NO)] and [Mn(5-CH 3 SALDPT)(NO)] (SALDPT = dianionic pentadentate Schiff base) display ν NO at 1735 and 1715 cm -1 , respectively. 10b,13a, The latter ν NO values are close to that of [Mn(CN) 5 (NO)] 3- (1725 cm -1 ), an organometallic species with an effectively Mn(I) center . Although this argument favors the {Mn(I)−NO + } formulation for the diamagnetic complexes such as [Mn(TPP)(NO)], controversy still exists in the case of complexes derived from ligands such as the Schiff bases 13 that are usually not very supportive of metals in low oxidation states.…”

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confidence: 95%

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Reactions of NO with Mn(II) and Mn(III) Centers Coordinated to Carboxamido Nitrogen: Synthesis of a Manganese Nitrosyl with Photolabile NO

et al. 2004

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The Mn(II) and Mn(III) complexes of the pentadentate ligand N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide (PaPy3H; H is the dissociable carboxamide H), namely, [Mn(PaPy3)(H2O)]ClO4 (1) and [Mn(PaPy3)(Cl)]ClO4 (2), with bound carboxamido nitrogen have been isolated and characterized. The high-spin Mn(II) center in 1 is very sensitive to dioxygen, and this complex is rapidly converted into 2 upon reaction with Cl- in air. The bound carboxamido nitrogen in 1 is responsible for this sensitivity toward oxidation since the analogous Schiff base complex [Mn(SBPy3)Cl]ClO4 (4) is very resistant to oxidation. Reaction of NO with 1 affords the diamagnetic [Mn-NO]6 nitrosyl [Mn(PaPy3)(NO)]ClO4 (5). Complexes with no bound carboxamido nitrogen such as 4 and [Mn(PaPy3H)(Cl)2] (3) do not react with NO. No reaction with NO is observed with the Mn(III) complexes 2 and [Mn(PaPy3)(MeCN)]2+ either. Collectively these reactions indicate that NO reacts only with the Mn(II) center ligated to at least one carboxamido nitrogen. Both the carbonyl and N-O stretching frequencies (nu(CO) and nu(NO)) of the present and related complexes strongly suggest a [low-spin Mn(II)-NO*] formulation for 5. The alternative description [low-spin Mn(I)-NO+] is not supported by the spectroscopic and redox behavior of 5. Complex 5 is the first example of a [Mn-NO]6 nitrosyl that exhibits photolability of NO upon illumination with low-intensity tungsten lamps in solvents such as MeCN and H2O. The rapid NO loss from 5 leads to the formation of the corresponding solvato species [Mn(PaPy3)(MeCN)]2+ under aerobic conditions. Oxidation of 5 with (NH4)2[Ce(NO3)6] in MeCN affords the highly reactive paramagnetic (S = 1/2) [MnNO]5 nitrosyl [Mn(PaPy3)(NO)](NO3)2 (6) in high yield. Spectroscopic and magnetic studies confirm a [low-spin Mn(II)-NO+] formulation for 6. The N-O stretching frequencies (nu(NO)) of 5, 6, and analogous nitrosyls reported by other groups collectively suggest that nu(NO) is a better indicator of the oxidation state of NO (NO+, NO*, or NO-) in non-heme iron and other transition-metal complexes with bound NO.

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Section: Resultsmentioning

confidence: 99%

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confidence: 95%

Reactions of NO with Mn(II) and Mn(III) Centers Coordinated to Carboxamido Nitrogen: Synthesis of a Manganese Nitrosyl with Photolabile NO

et al. 2004

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“…Upon evaporation, these carbonylated solutions yielded spectroscopically pure 5 , indicating that the CO is kinetically labile. It has been known for some years that [Fe(CN) 6 ] 4- can be carbonylated at high pressures to give [Fe(CN) 5 (CO)] 3- …”

Section: Resultsmentioning

confidence: 99%

Binding of π-Acceptor Ligands to (Triamine)iron(II) Complexes

Moreland

Rauchfuss

2000

Inorg. Chem.

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A series of (Me3TACN)FeII derivatives with soft coligands have been investigated, where Me3TACN is N,N',N"-trimethyl-1,4,7-triazacyclononane. Treatment of Me3TACN with FeCl2 afforded a compound with the empirical formula (Me3TACN)FeCl2 (1). Compound 1, which is a versatile precursor reagent, was shown by single-crystal X-ray diffraction to be the salt [(Me3TACN)2Fe2Cl3][(Me3TACN)FeCl3], containing isolated [(Me3TACN)2Fe2Cl3]+ and [(Me3TACN)FeCl3]- subunits. Treatment of 1 with NaBPh4 gave the known [(Me3TACN)2Fe2Cl3]BPh4, while the addition of Me3TACN to FeCl4(2-) gave [(Me3TACN)FeCl3]-. Oxygenation of 1 afforded [(Me3TACN)FeCl2]2(mu-O), which was shown crystallographically to be centrosymmetric with a pair of distorted octahedral Fe centers. The Fe-N bond trans to the Fe-O bond is elongated by 02 A relative to the other Fe-N distances. Solutions of 1 and thiolates absorb CO to give [(Me3TACN)Fe(SPh)(CO)2]BPh4 and (Me3TACN)Fe(S2C2H4)(CO) (nu CO = 1896 cm-1). Treatment of 1 with excess CN- afforded [(Me3TACN)Fe(CN)3]-, isolated as its PPh4+ salt 5. Crystallographic and spectroscopic studies show that 5 is low spin with a C3v structure; its Fe-N distances contracted by 023 A relative to those in [(Me3TACN)FeCl3]-. Aqueous solutions of 1 bind CO upon the addition of CN- to produce (Me3TACN)Fe(CN)2(CO) (6) Analogous to 6 is (Me3TACN)Fe(CN)2(CNMe), prepared by methylation of 5. The metastable dicarbonyl [(Me3TACN)FeI(CO)2]I was prepared by treatment of FeI2(CO)4 with Me3TACN and was crystallographically characterized as its BPh4- salt. Values of E1/2 for [(Me3TACN)FeCl3]-, 5, and 6 are -0409, -0640, and 0533 V vs Fc/Fc+, respectively.

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“…In these very few examples of LS Mn(II) complexes, the metal is surrounded by a N-rich chromophore with N atoms mainly arising from cyano or oxime groups. Examples of chromophores include N3O3 [33], N4S2 [34], N4O2 [35] and N6 [36][37][38][39], including six -CN groups [40,41]. The assignation of the LS centers to the anionic chain (where Mn1 is surrounded by four -CN groups from four tcnopr3OH´ligands) is straightforward, since the ligand field of these -CN groups is expected to be much larger than the one created by the four water molecules coordinated to Mn2 in the cationic chain.…”

Section: Magnetic Propertiesmentioning

confidence: 99%