Magnetic properties of anhydrous and hydrated dimethylphosphinates of manganese(II). The crystal and molecular structure of poly-bis(μ-dimethylphosphinato)diaquomanganese(II)

Abstract

Can. J. Chem. 63, 1055 (1985. The dimethylphosphinate of manganese(ll), Mn[(CH3)zP02]2, and its dihydrate have been prepared and studied using magnetic susceptibility, differential scanning calorimetry, and electronic and vibrational spectroscopic methods. The dihydrate was obtained in crystalline form and a single crystal X-ray diffraction study revealed a polymeric structure.Crystals of~poly-bis(p-dimethylphosphinato)diaquomanganese(l1) are monoclinic, o = 20.722(3), b = 4.8652(2), c = 11.0689(14) A, P = 102.209(7)", Z = 4, space group C2/c. The structure was solved by conventional heavy-atom methods and was refined by full-matrix least-squares procedures to R = 0.030 and R,,. = 0.033 for 983 reflections with I 2 3u(I). The structure consists of infinite centrosymmetric chains of Mn(ll) atoms linked by double phosphinate bridges and extending along the crystallographic b axis. The water molecu!es are involved in both interchain and bifurcated intrachain hydrogen bonding (0.--0 = 2.734(2), 2.899(3) and 3.120(3) A). The coordination about Mn is slightly distorteG octahedral with librationcorrected bond lengths Mn-O(phosphinato) = 2.156(2) and 2.212(2), Mn-OH2 = 2.247(2) A. Magnetic susceptibility studies on the dihydrate from 300 to 4.2 K reveal a magnetic moment of -5.9 BM over most of the range and give no evidence for significant magnetic exchange. The anhydrous compound, which is considered on the basis of indirect evidence to retain the double phosphinate bridged structure exhibited by the dihydrate, shows relatively strong antiferromagnetic behaviour. The data have been analyzed according to two theoretical models both of which employ the isotropic Heinsenberg Hamiltonian. The scaling model of Wagner and Friedberg gives J = -2.94 cm-' and g = 2.02 and the interpolation scheme of Weng gives J = -2.69 cm-' and g = 2.01. The magnitude of the exchange coupling is considered in relation to that observed in related manganese compounds and possible reasons for the observed damping of the exchange on hydration are discussed. Les etudes de susceptibiliti magnttique, rCalisCes avec I'hydrate double ii des temperatures allant de 300 a 4,2 K, rtvklent la presence d'un moment magnttique de 5.9 BM environ sur presque tout I'intervalle considtrk. Le compose anhydre, qui, d'aprts des preuves indirectes, conserverait la structure pontCe double phosphinate qui existe dans le dihydrate, exhibe un comportement antiferromagnktique relativement fort. On a analysC les donntes selon deux modtles thkoriques qui utilisent I'Hamiltonien isotrope de Heinsenberg. Le modble proportionnt de Wagner et Friedberg permet de prtdire des valeurs de J = -2,94 cm-' et g = 2,02 alors que le schema d'interpolation de Weng conduit a des valeurs de J = -2,69 cm-' et g = 2,01. On considkre I'amplitude du couplage d'echange en rapport avec celui observe avec des composes apparentes du mangankse et on discute des raisons qui pourraient expliquer le fait que I'tchange accompagnant I'hydratation est amoindri.[Traduit par le journal] Introduction The po...

A binuclear manganese(II) complex, decaaqua(μ-1,2,4,5-benzenetetracarboxylato-O1:O4)dimanganese(II) hydrate

“…There is no signi®cant difference in the coordination distance between carboxyl and water O atoms. Most of the coordination bond distances in the present complex range from 2.1516 (14) to 2.216 (2) A Ê and are comparable to those reported previously, for example, 2.181 (1) in [Mn(H 2 O) 6 ] 2+ ÁZnBr 2À (Villella et al, 1986), 2.221 (6) in [Mn(HC 4 et al, 1995) and 2.247 (3) A Ê in [Mn II (Me 2 PO 2 ) 2 ]Á2H 2 O (Cicha et al, 1985). It is notable that the Mn1ÐO19 distance of 2.2922 (13) A Ê in the present Mn II complex is signi®cantly longer than the Mn II ÐO water distances reported so far for Mn II complexes and very close to the MnÐ O water distances of 2.319 (3) (Horwitz et al, 1995) and 2.287 (5) A Ê (Li et al, 2000) found in the axial direction of two Mn III complexes, both of which showed signi®cant Jahn±Teller distortion.…”

Structure and magnetic properties of monophenylphosphinate bridged chain polymers of manganese(II), [MnL2(HPhPO2)2]x (where L = HPhPO2H, CH3CONH2, H2O, HCONH(CH3), and C5H5N)

“…As discussed above, there is infrared evidence for unsymmetrical 0-P-0 units in this compound and this too may contribute to weakening the exchange. The aquo complex, 5, should exhibit both intrachain and interchain hydrogen bonding as has, in fact, been observed previously for the dimethylphosphinate analogue (8). This would be expected to give symmetrical 0-P-0 bridges in 5, a result supported by the infrared spectral studies described above.…”

“…Compounds of composition ML2(R2P02), in which metal ions are linked in chains by double phosphinate bridges forming square planar MO, chromophores with axially coordinated L groups are also known (8,9). The three atom 0-P-0 bridges in these polymeric materials have been shown to be capable of '~u t h o r to whom correspondence should be addressed.…”

Dimethylphosphinato and Dimethylarsinato Complexes of Palladium(II), [Pd(Me2PO2)2]3 and Pd(Me2AsO2)2, and their Adducts

“…The oxygen analogue of Me 2 PS 2 H, dimethylphosphinic acid Me 2 P(O)OH ( 1 ) reacts with metal cations to give “metal‐phosphinate‐bridged coordination polymers”, e.g. with Be II 5, Cr III 6, Mn II 7, Cu II 8. It coordinates to metal carbonyls (to yield e.g.…”