Bonding Scheme, Hydride Character, and Magnetic Paths of (HPO3)2

Subscriber access provided by NEW MEXICO STATE UNIV

Article

Bonding Scheme, Hydride Character and Magnetic Paths of (HPO) Versus (SeO) Building Units in Solids 3

2–

3

2–

Vadim Mikhailovich Kovrugin, Elijah E Gordon, Emine Esra Kasapbasi, Myung-Hwan Whangbo, Marie Colmont, Oleg Iohannessovich Siidra, Silviu Colis, Sergey Vladimirovich Krivovichev, and Olivier Mentre J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.5b10889 • Publication Date (Web): 05 Jan 2016 Downloaded from http://pubs.acs.org on January 8, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

The Journal of Physical Chemistry C is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

Bonding Scheme, Hydride Character and Magnetic Paths of (HPO3)2– Versus (SeO3)2– Building Units in Solids Vadim M. Kovrugin†,‡, Elijah E. Gordon§, Esra E. Kasapbasi∥, Myung-Hwan Whangbo*,§, Marie Colmont†, Oleg I. Siidra‡, Silviu Colis⊥, Sergey V. Krivovichev‡, and Olivier Mentré*,† †

UCCS, UMR 8181, Université Lille Nord de France, USTL, 59655 Villeneuve d’Ascq, France.

‡

Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg, Russia.

§

Department of Chemistry, North Carolina State University Raleigh, North Carolina 27695-8204, USA.

∥

Biomedical Equipment Technology Program, Istanbul Aydin University, Istanbul, Turkey.

Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 CNRS and Université de Strasbourg and UDS-ECPM, 67034 Cedex 2 Strasbourg, France.

⊥

Supporting Information Placeholder ABSTRACT: The abilities of the (HPO3)2– and (SeO3)2– anions as structure building units and as spin exchange paths between magnetic ions were investigated by preparing and analyzing the isostructural Fe2(SeO3)3 and Fe2(HPO3)3. In both compounds, 2– 2– 2– the face-sharing Fe2O9 dimers are interconnected into chains by the (HPO3) and (SeO3) anions. The (HPO3) is the structural 2– counterpart of the Se electron lone pair of (SeO3) due to the weak hydride character of the terminal hydrogen. However, they differ considerably as spin exchange paths between magnetic cations. Both compounds exhibit an effective magnetic dimer behavior, unexpectedly arising from the inter-dimer Fe–O∙∙∙O–Fe exchange along the chain, but weaker in Fe2(HPO3)3 by a factor of ∼3. It is consistent with the general tendencies of the phosphite anions to act as a weak magnetic mediator, which is caused by 3+ 3+ the through-bond effect of the P ion in the Fe–O∙∙∙P ∙∙∙O–Fe exchange path, much weaker than in the selenite phase in absence 3+ are also discussed. of P d contribution. Reasons for stronger exchanges through phosphates or sulfates

INTRODUCTION Since the recent reports of unexpected P∙∙∙H–O hydrogen 1 3+ 2+ 2 bonds in gas phases and direct As ∙∙∙Co bond in oxide, the 3+ 3+ 4+ bonding possibilities of lone pair cation P , As and Se have generated renewed interests. The phosphite anion 2– (HPO3) is commonly encountered as a tridentate tetrahedral ligand in solids, and can be regarded as resulting from phosphonic acid HPO(OH)2 upon deprotonation. Although 2– the (HPO3) anion in solution has been the subject of spec3 troscopic studies, there has been no clear characterization of its P–H bond in crystalline solids except for the bond valence 4 2– parameter proposed for its P–O bond. The (SeO3) anion has a tetrahedral shape (including its Se electronic lone pair) 2– as does (HPO3) , both acting as tridentate ligands in solids. 2– Thus, though not commonly observed, the (SeO3) and 2– (HPO3) anions can constitute similar building units for solids, as found for inorganic phases they form with trivalent 3+ 5–8 transition-metal M such as M2(SeO3)3 and M2(HPO3)3. This implies that the Se lone pair and the P–H bond can replace each other, which suggest that the H atom of the P– H bond might possess a small negative charge and hence weak hydride character. In terms of the relative electronegativities of H and P, this view is supported by the Allen’s 9 10 (2.300 vs. 2. 253) and by Pauling’s (2.20 vs. 2.19) scales, but 11 not supported by Allred’s (2.1 vs. 2.2) scale. It is of interest therefore to examine the effective polarization of the P–H

bond in inorganic solids. Concerning the magnetic proper2– ties, the (SeO3) anion (including the Se lone pair) is larger 2– than the (HPO3) anion (Se–O ca. 1.7 Å, P–O ca. 1.5 Å) lead3+ 2– ing to magnetic ions M further separated by (SeO3) than 2– by (HPO3) . Therefore, one might speculate weaker spin exchanges for M2(SeO3)3 with respect to M2(HPO3)3 by considering the through-space (TS) interactions although most magnetic inorganic phosphites show weak magnetic exchanges compared to other oxo-anion ligands. However, it is known that M–O∙∙∙X∙∙∙O–M spin exchanges are also affected by through-bond (TB) interactions, which can dominate over 12 the TS interactions. In the present work we probe the 2– aforementioned questions concerning the apparent (SeO3) 2– and (HPO3) analogy by preparing the novel Fe2(SeO3)3 5 phase and the previously reported Fe2(HPO3)3, characterizing their structural and magnetic properties, and investigating their spin exchanges on the basis of density functional theory (DFT) calculations.

RESULTS AND DISCUSSION Synthesis and Structure analysis Single crystals of Fe2(SeO3)3 and Fe2(HPO3)3 were prepared by hydrothermal reaction between 160 and 200°C using SeO2 or H3PO3 and FeCl3. (For details of synthetic procedures, see S1 of the Supporting Information (SI). The as-prepared products are nearly single phases. Single crystals are yellow for

ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Fe2(SeO3)3 and colorless for Fe2(HPO3)3 (Figure 1a,b). They crystallize in the P63/m space group with the following lattice parameters and final agreement factors: a = 8.0195(2) Å, b = 7.3700(2) Å, R1 = 1.54 % for Fe2(HPO3)3; a = 7.8720(9) Å, b = 7.3258(10) Å, R1 = 1.57 % for Fe2(SeO3)3. For details of the crystallographic data, see S2 of the SI. The main interatomic distances are given in Table 1. The experimental and theoretical powder XRD patterns are in good agreement (see S3 of the SI). In Fe2(HPO3)3 the presence of the typical P–H bond was verified by infrared spectrum, which shows the ν(P–H) –1 vibrational band at 2445 cm (Figure 1c), as found in other 13,14 2– compounds containing the (HPO3) anion (see S4 of the SI). The new phase Fe2(SeO3)3 is isostructural with the previ6 5 7 8 ously reported Sc2(SeO3)3 and M2(HPO3)3 (M = Fe, Sc, Al, 8 Ga ) phases by regarding the H−P bond pair as identical to the Se lone pair in shape.

Page 2 of 8 2–

lone pairs (LPs) of (SeO3) ions, which is in support of the analogy between the P-H and the Se LP. For further discussion of the LP localization and the Se–LP dipole moment, based on the Verbaere method implemented in the program 15 16,17 Hybrid, see S5 of the SI. Using the Henry’s method (see S5 of the SI), we calculate the charge densities on the atoms 5 6,7 of M2(SeO3)3 and M2(HPO3)3 (M = Fe, Sc ), as summarized in Table 2. A slightly negative charge of -0.024 is found for Fe2(HPO3)3, and -0.068 for Sc2(HPO3)3, for the H atoms. This is consistent with Allen’s and Pauling’s electronegativity + – scales (χH>χP). A similarly weak Pδ -Hδ polarization is systematically found for various inorganic compounds contain2– ing (HPO3) anions (see Table S5.a of the SI). To verify the slight hydride character of the H atom, we carried out DFT calculations on a hypothetical isolated complex Fe2(HPO3)3 with C3v symmetry (see S6 of the SI) using the B3LYP func18,19 20 tional and the 6-31 g(d) basis set, and evaluated the 21 natural bond orbital (NBO) charge densities on the atoms. Our calculations show a small negative charge on the H atom (i.e., –0.07), consistent with the above observation.

Table 1. Selected interatomic distances (Å) for Fe2(HPO3)3 and Fe2(SeO3)3 Distance

Fe2(HPO3)3 T=P

Figure 1. Optical microscope images of (a) Fe2(SeO3)3 and (b) Fe2(HPO3)3. (c) IR spectra of Fe2(SeO3)3 and Fe2(HPO3)3. The crystal structure of Fe2(TO3)3 (T = Se, HP) consists of Fe2O9 dimer chains running along the c-direction. Each Fe2O9 dimer is made up of two face-sharing FeO6 octahedra (Figure 2b). The terminal six oxygen atoms of every two 2– adjacent Fe2O9 dimers are bridged by three anions, (SeO3) 2– in Fe2(SeO3)3 and (HPO3) in Fe2(HPO3)3, to form chains parallel to the c-direction. In one chain, the bridging oxygen atoms of the Fe2O9 dimers are corner-shared with the anions of its three adjacent chains, forming hexagonal tunnels along the c-direction (Figure 2a,c). The average Fe–O bond lengths of Fe2(SeO3)3 and Fe2(HPO3)3 are nearly the same (2.015 Å and 2.007 Å, respectively), and so are the Fe∙∙∙Fe distances (2.987 Å and 2.980 Å, respectively) in their Fe2O9 dimers. The Se–O bonds (1.676–1.722 Å) are longer than the P–O bonds (1.513–1.540 Å) leading to narrower tunnels in the 2– selenite. The shortest H∙∙∙H contacts between two (HPO3) anions in Fe2(HPO3)3 are 2.484 Å, which is close to the van der Waals radii sum (2.4 Å). 2–

3+

Fe2(SeO3)3 T = Se

4+

Fe1–O1

3× 1.9188(10)

3× 1.9208(13)

Fe1–O2

3× 2.0953(10)

3× 2.1090(13)

2.0071

2.0149

Fe1–Fe1

2.9800(4)

2.9873(7)

T1–O1

2× 1.5127(10)

2× 1.6763(1)

T1–O2

1× 1.5398(14)

1× 1.7220(18)

1.5217

1.6915

P1–H1

1.31(2)

Se1–E

a

0.2599

a

lone electron pair has been localized using the Verbaere method implemented in the program Hybrid (see S5 in the SI)

It should be pointed out that the hexagonal tunnels in both M2(HPO3)3 and M2(SeO3)3 are decorated by weak but significant electron density, giving the possibility of cationic intercalation. Similar tunnel structures based on P–H or Se lone pairs can be found in the isomorph frameworks of 2+ 2+ 2+ 2+ 2+ 2+ 22–25 M11⧠1(HPO3)8(OH)6 (M = Zn , Co , Ni , Fe , Mn ) 2+ 2+ 2+ – – 26 and M12X2(SeO3)8(OH)6 (M = Co , Ni ; X = OH , F ). This 2– 2– reinforces our conclusion that the (HPO3) and (SeO3) anions are very similar building units of solids (Figure 2d,e).

2–

In both (HPO3) and (SeO3) , the O atom is a stronger donor to a transition-metal cation than are P–H and Se, leaving the P–H and the Se lone pair unused. The P–H bonds are pointed toward the axis of the empty tunnel as do the Se


Page 3 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 2. Calculated partial charges using WinPACHA16,17 on the atoms of isomorphous M2(HPO3)3 and M2(SeO3)3 (M = Fe, Sc) Formula

Fe–Fe or Sc–Sc a Tunnel Ø

P–P or Se–Se b Tunnel Ø

Partial charges

Fe2(HPO3)3

9.26 Å

5.35 Å

–0.024

Fe2(SeO3)3

9.08 Å

4.54 Å

Sc2(HPO3)3

9.60 Å

5.53 Å

Sc2(SeO3)3

9.42 Å

4.65 Å

H

P or Se

–0.068

O

Fe or Sc

Ref.

+0.170

–0.382 (×2), –0.293

+0.529

*,

+0.056

–0.353 (×2), –0.280

+0.577

*

+0.304

–0.602 (×2), –0.695

+1.061

7

+0.088

–0.558 (×2), –0.661

+1.131

6

5

a

diameter measured as the shortest distance between two Fe or Sc atoms; diameter measured as the shortest distance between two P or Se atoms; * this work

b

Figure 2. Projection of the crystal structures of (a) Fe2(HPO3)3, (c) Fe2(SeO3)3 along the c-direction. (b) View of the dimer chains growing along the b-direction. Views of the crystal structures of (d) M11⧠1(HPO3)8(OH)6 and (e) M12X2(SeO3)8(OH)6 along the cdirection. E denote the electron lonepairs. Finally dealing with the phosphite system, a number of 3+ hydrated phases are reported with conservation of the Fe 27 28 state, i.e. Fe2(SeO3)3∙H2O, Fe2(SeO3)3∙3H2O, 29 Fe2(SeO3)3∙6H2O. Their crystal structures is discussed in the supplementary Materials (S9). They are out of the scope of our study due to the loss of the dimeric units common between the phosphite and selenite analogs. In addition, no magnetic properties were reported for any of these compounds so far.

Magnetic susceptibilities 2–

Compared to other tetrahedral anion such as (SeO3) or 3– 2– (PO4) , the phosphite (HPO3) anion seems exaggeratedly ineffective in mediating antiferromagnetic (AFM) spin exchanges between adjacent magnetic transition-metal centers.

It mostly leads to extended Curie-Weiss (CW) thermal regimes with no long-range magnetic ordering. For instance, I III the behaviors reported for the A [M (HPO3)2] (A = K, NH4, 13 Rb and M = V, Fe) show a slight deviation from the CW law. So far, a long-range antiferromagnetic ordering was observed 3+ only for Fe (S = 5/2) at a very low Néel temperature (TN = 9 K). It was concluded in a recent work dealing with magnetic properties of hybrid inorganic-organic cobalt (II) phos30 phites, that “phosphite ligands are not particularly effective at mediating antiferromagnetic couplings”. The magnetic susceptibilities χ(T) of Fe2(SeO3)3 and Fe2(HPO3)3 are given in Figure 3a. The χ(T) variations recorded for Fe2(SeO3)3 and Fe2(HPO3)3 show a broad maximum at ∼50 K and a sharper one at ∼25 K, respectively. For Fe2(HPO3) a prior study clearly shows at lower temperature



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(TN=19.7 K) the setting of a 3D magnetic ordering by both 31 specific heat and Mössbauer spectroscopy. For Fe2(SeO3)3 the d(χ)/d(T) plot versus T shows a peak at T =24 K that may aso correspond to 3D ordering in this compound. By fitting the linear regions of the 1/χ(T) vs. T plots (Figure 3b) using the Curie-Weiss law, we obtain the Curie-Weiss temperature θCW of –197.6 K for Fe2(SeO3)3 and –56.5 K for Fe2(HPO3)3. 31 This latter value is close to the value fitted previously, θCW = -36K and the difference could stem from the small number of 31 experimental points in the original report. Although in both compounds, the dominant spin exchange is AFM, it is stronger for Fe2(SeO3)3 than for Fe2(HPO3)3 by a factor of ∼3. As already discussed, both compounds consist of Fe2O9 dimers with similar Fe∙∙∙Fe distances and ∠Fe–O–Fe angles. Thus, as a simple spin-lattice model for simulating their magnetic susceptibilities χ(T), one might consider an isolated S = 5/2 dimer model. Our simulations using this model lead to abnormally low g values (i.e., about 1.75).

Page 4 of 8

where x = J/kBT and µ0, NA, µB and kB have their usual meanings. To take into account the inter-dimer interactions, we 33,34 used a mean field-type approximation in which a dimer interacts with eight surrounding dimers with inter-dimer exchanges Jinter; two apical, above and below a given dimer within a chain as well as six dimers from the six adjacent chains. Then we obtain: χ%&

'()* +()* ,,,

. /)0123 '()* +()* ,,,

4 5 6

-

7 8 ,

(2)

After fitting the high temperature region (above the bump, i.e. above TN for Fe2(HPO3)3), the resulting Jdim and Jinter exchanges are both AFM, and are significantly stronger for Fe2(SeO3)3 [Jdim/kB = –20.18(2) K and Jinter/kB = –4.2(1) K, g = -5 1.993(8), χ0 = 95(12)×10 emu/Oe∙mol] than for Fe2(HPO3)3 [Jdim/kB = –7.71(2) K and Jinter/kB = –0.82(4) K, g = 2.054(5), χ0 -5 = 290(10)×10 emu/Oe∙mol]. We now examine the possible reasons why the spin exchanges are weaker for Fe2(HPO3)3 than for Fe2(SeO3)3. We consider the spin exchanges J1 and J2 within a chain as well as J3 and J4 between adjacent chains. J1 is a Fe–O–Fe exchange, 12,35 and J2 – J4 are Fe–O∙∙∙O–Fe spin exchanges. The geometrical parameters associated with these exchange paths, summarized in Figure 4, show that the exchange paths J1 of Fe2(SeO3)3 and Fe2(HPO3)3 are very similar in the ∠Fe–O–Fe angle and the Fe∙∙∙Fe distance, so that J1 cannot be responsible for the large difference in the Jdim values.

Figure 3. (a) χ(T) vs. T and (b) 1/χ(T) vs. T plots obtained for Fe2(SeO3)3 and Fe2(HPO3)3 at 0.02 T in blue and black respectively. The red curves represent (a) the curie-Weiss fit and (b) the simulation using a dimer model with inter-dimer interactions included (see the text). * – shows the Morin transition of the minor amount of α-Fe2O3 present in the selenite compound. For more realistic results, the interaction between dimers was integrated in the model. In terms of the partition func32 tion method, the susceptibility χdim(T) of a dimer made up of two S = 5/2 ions is written as (the red curves in Figure 3a): χ T

" #

!

!

,

(1)

Figure 4. Geometrical parameters associated with the exchange paths J1 – J4 of Fe2(SeO3)3 and Fe2(HPO3)3 and values of the exchanges (in kBK) obtained from DFT+U calculations


Page 5 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


a

b ets

ets

ets/tb

ets/tb

c

n+

Figure 5. Effects of the TS and TB interactions in an M–O∙∙∙A ∙∙∙O–M exchange path. (a) A consequence of strong TS and weak n+ TB interactions in (a) and that of weak TS and strong TB interactions in (b). (c) Interaction of the dπ orbital of A with the 2p orbitals of the oxygen atoms present in the magnetic orbitals of M. The Fe–O∙∙∙O–Fe exchanges J2 along the chain show a substantial difference in the O∙∙∙O distances, 2.627 Å in Fe2(SeO3)3 and 2.536 Å in Fe2(HPO3)3. In general, a spin exchange of the M–O∙∙∙O–M type, where M is a transition metal 35 ion, depends sensitively on the O∙∙∙O contact distance but suggests an expected stronger Jdim for Fe2(HPO3)3 than for Fe2(SeO3)3 due to O∙∙∙O distance in Fe2(HPO3)3. The same puzzle arises from the consideration of the Fe–O∙∙∙O–Fe exchanges J3 and J4. To resolve this conceptual difficulty, we evaluate the values of the exchanges J1 – J4 quantitatively as will be discussed in the next section.

Analysis of spin exchanges We extract the values of J1 – J4 on the basis of the energy12 mapping analysis by using the five ordered spin states of Fe2(SeO3)3 and Fe2(HPO3)3 depicted in Figure S7.a of the SI 36 on the basis of DFT+U calculations and the spin Hamiltonian defined below: : − ∑>D? J>? S:A ∙ S:C , H (3) where Jij = J1 – J4 (see S7 of the SI for details). The values of J1 – J4 determined by the mapping analysis are summarized Figure 4, which shows that: (a) all spin exchanges J1 – J4 are AFM in both Fe2(SeO3)3 and Fe2(HPO3)3; (b) the intra-dimer exchange J1 is weakly AFM, which can be related to the fact that the ∠Fe–O–Fe angles very close to 90°; (c) the inter-dimer exchange J2 dominates over other exchanges in each compound;

(d) the J2 of Fe2(SeO3)3 is stronger than that of Fe2(HPO3)3 by a factor of ∼3. These results are in a very good agreement with the susceptibility fits, and J2 is identified as the exchange corresponding to Jdim, however our puzzle still remains; the Fe– O∙∙∙O–Fe exchange J2 is more strongly AFM for Fe2(SeO3)3 despite that the O∙∙∙O distance is longer for Fe2(SeO3)3. This arose from the fact that we considered only the through3+ space (TS) interactions between Fe ions. In general, an M– O∙∙∙O–M exchange is accompanied by an intervening cation n+ 4+ 3+ n+ A (i.e., Se or P here) to form the path M–O∙∙∙A ∙∙∙O–M. In this path, the magnetic orbitals of the two magnetic ions M interact to give the in-phase and out-of-phase combinations, Ψ+ and Ψ−, respectively. Given the energy split ∆e between Ψ+ and Ψ−, the associated AFM exchange JAF is pro2 2 12,35 portional to (∆e) , JAF ∝ -(∆e) . The magnitude of ∆e is governed by the TS interaction as well as by the throughbond (TB) interaction associated with the empty dπ-orbitals n+ of the A cation (Figure 5a,b). The energy split ∆ets from the TS interaction increases with decreasing the O∙∙∙O distance. The energy of Ψ− is lowered by its TB interaction with dπ (Figure 5c), so the overall energy split between Ψ+ and Ψ− changes to ∆ets/tb (i.e., ∆e). The J2 exchange path has a shorter O∙∙∙O distance in Fe2(HPO3)3 than in Fe2(SeO3)3, so that ∆ets is larger for Fe2(HPO3)3 (Figure 5a,b). Since J2 is much stronger for Fe2(SeO3)3 than for Fe2(HPO3)3 despite that the ∆ets is smaller for Fe2(SeO3)3, the TB effect must be much stronger for Fe2(SeO3)3 than for Fe2(HPO3)3, eventually leading to a greater ∆e for Fe2(SeO3)3. This is expected because 4+ the empty 4d-orbitals of Se lie lower in energy than the 3+ empty 3d-orbitals of P so that the lowering of Ψ− by the dπ-



Page 6 of 8

n+

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

orbitals of A is much stronger for Fe2(SeO3)3. This argument implies that the resulting occupied bands of Fe2(SeO3) will have contributions of the Se dπ-orbitals due to their mixing with Ψ−. We confirm this reasoning by calculating the projected density of states (PDOS) plot for the Se 4d orbitals in Fe2(SeO3)3 and that for the P 3d orbitals in Fe2(HPO3)3. As presented in Figure S8 of the SI, the PDOS plot for Fe2(SeO3)3 has Se 4d contributions below the Fermi level, while that for Fe2(HPO3)3 does not have P 3d contributions below the Fermi level. Finally, it is of interest to note that the phosphite anion 2– (HPO3) provides a much weaker spin exchange path than most of tetrahedral oxo-anions including the commonly 3– found phosphate (PO4) ligands despite that their P–O bond lengths and ∠P–O–P angles are similar. For instance, α-and β-Li3Fe2(PO4)3 orders antiferromagnetically below TN = 30.0 37,38 and 27 K, respectively, while all Fe∙∙∙Fe distances are long3+ er (> 4.5 Å) than in Fe2(HPO3)3. The TN values of other Fe + 13 phosphite salts A [Fe(HPO3)2] (A = K, NH4, Rb) are lower than 9 K and comfort the weak magnetic connectivity through phosphites. This would be a consequence of the fact 3– that the (PO4) anion has higher-lying oxygen lone pairs, 3+ and hence are closer in energy to the Fe d-orbitals, than 2– 3– does the (HPO3) anion. The latter makes the (PO4) anion 3+ interact more strongly with Fe ions and become a more 2– efficient spin exchange path than the (HPO3) anion. In 2– terms of the negative charge, the sulfate anion (SO4) is 2– similar to the (HPO3) anion. However, in terms of group 2– electronegativity, the (SO4) anion is more electronegative 2– than the (HPO3) anion. This makes the empty levels of 2– 2– (SO4) lie lower in energy than those of (HPO3) . As a re2– sult, (SO4) would be a more efficient spin exchange path 2– than (HPO3) . In agreement with expectation, Fe2(SO4)3 is 39 found to order at 29 K. Finally, the poor penchant of phosphite groups for transmission of magnetic exchanges make this anion a very attractive candidate for efficient spacers in the frame of Low-D magnetic materials.

ACKNOWLEDGMENT This work was carried out under the framework of the Multi-InMaDe project supported by the ANR (Grant ANR 2011-JS-08 00301). The Fonds Européen de Développement Régional (FEDER), CNRS, Région Nord Pas-de-Calais, and Ministère de l’Education Nationale de l’Enseignement Supérieur et de la Recherche are acknowledged for funding the X-ray diffractometers. V.M.K. thanks l’Ambassade de France en Russie and l’Agence Campus France (Contract Nos. 768231K, 779116K, 794852B, 808399A, 808400J, and 838014G) for the partial support of this work. S.V.K. and O.I.S. acknowledge financial support from St. Petersburg State University (Internal Grant 3.38.136.2014). M.H.W thanks the NERSC Center and the HPC Center at NCSU for their generous computing resources.

ASSOCIATED CONTENT Supporting Information Detailed synthetic procedures, details of single crystal and powder X-ray diffraction analyses, IR spectroscopy, partial charge calculations, procedure of lone electron pairs localization, Ab initio MO calculations of charge density, computational details of spin exchange evaluation, PDOS plots of Fe2(SeO3)3 and Fe2(SeO3)3. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Authors ,†

* [email protected] ,§ * [email protected]

Notes The authors declare no competing financial interests.

CONCLUSION As structural building units with metal cations, the 2– 2– (HPO3) and (SeO3) anions are similar giving the keys for the design of new “selenite inspired” phosphite compounds. This is due to the oxygen lone pairs making a stronger bonding with the cation orbitals than do both the terminal H–P bond pair and Se electron lone pair. The H atom of the H–P 2– bond in (HPO3) has a very small negative charge resulting in a weak hydride character, as the electronegativity of H is slightly larger than that of P. In the isostructural Fe2(SeO3)3 and Fe2(HPO3)3 compounds, it involves the Se LPs and P–H terminal bonds directed toward empty tunnels. Their magnetic susceptibilities are well simulated by an effective dimer model. Nevertheless, the dominant spin exchange is not the Fe–O–Fe exchange J1 of the structural dimer Fe2O9, but the inter-dimer Fe–O∙∙∙O–Fe exchange J2 along the dimer chain. 2– As reported in the literature, the (HPO3) group is generally inefficient AFM spin exchange mediator, as verified here by the J2 value of Fe2(SeO3)3 found more strongly AFM than that of Fe2(HPO3)3 by a factor of ∼3 despite that the O∙∙∙O contact is longer for Fe2(SeO3)3. This is explained on the basis of the 3+ 3+ Through Bond (TB) effect of the P ion in the Fe–O∙∙∙P ∙∙∙O– 4+ Fe exchange path is much weaker than that of the Se ion in 4+ 39 the Fe–O∙∙∙Se ∙∙∙O–Fe exchange path.

REFERENCES

(1)

Hansen, A. S.; Du, L.; Kjaergaard, H. G. Positively Charged Phosphorus as a Hydrogen Bond Acceptor. J. Phys. Chem. Lett. 2014, 5, 4225–4231.

(2)

David, R.; Kabbour, H.; Pautrat, A.; Touati, N.; Whangbo, M.-H.; Mentré, O. Two-Orbital Three-Electron Stabilizing Interaction for Direct Co2+-As3+ Bonds Involving SquarePlanar CoO4 in BaCoAs2O5. Angew. Chem. Int. Ed. 2014, 53, 3111–3114.

(3)

Loub, J. Crystal Chemistry of Inorganic Phosphites. Acta Crystallogr. 1991, B47, 468–473.

(4)

Stringfellow, T. C.; Trudeau, J. D.; Farrar, T. C. Experimental and Theoretical Studies of the PhosphorusHydrogen Bond Length and Stretching Mode of the Phosphite Anion. J. Phys. Chem. 1993, 97, 3985–3989.

(5)

Sghyar, M.; Durand, J.; Cot, L.; Rafiq, M. Structure Du Phosphite de Fer: Fe2(PO3H)3. Acta Crystallogr. 1991, C47, 2515–2517.

(6)

Wontcheu,


J.;

Schleid,

T.

Sc2Se3O9:

Scandium(III)

Page 7 of 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry Oxoselenate(IV) According to Sc2[SeO3]3 with a Hexagonal “Lone-Pair” Channel Structure. Z. Anorg. Allg. Chem. 2003, 629, 1463–1465.

(7)

Ewald, B.; Prots, Y.; Kniep, R. Crystal Structure of Discandium Tris-Monohydrogenphosphate (III), Sc2(HPO3)3. Z. Kristallogr. 2003, 218, 377–378.

(8)

Morris, R. E.; Attfield, M. P.; Cheetham, A. K. Synthesis and Structures of Two Isostructural Phosphites, Al2(HPO3)3 and Ga2(HPO3)3. Acta Crystallogr. 1994, C50, 473–476.

(9)

Allen, L. C. Electronegativity Is the Average One-Electron Energy of the Valence-Shell Electrons in Ground-State Free Atoms. J. Am. Chem. Soc. 1989, 111, 9003–9014.

(10)

Pauling, L. The Nature of the Chemical Bond; 3rd ed.; Cornell University Library: Ithaca, United States, 1960.

(11)

Allred, A. L. Electronegativity Values from Thermochemical Data. J. Inorg. Nucl. Chem. 1961, 17, 215–221.

(12)

Xiang, H.; Lee, C.; Koo, H.-J.; Gong, X.; Whangbo, M.-H. Magnetic Properties and Energy-Mapping Analysis. Dalt. Trans. 2013, 42, 823–853.

(13)

Hamchaoui, F.; Alonzo, V.; Venegas-Yazigi, D.; Rebbah, H.; Le Fur, E. Six Novel Transition-Metal Phosphite Compounds, with Structure Related to Yavapaiite: Crystal Structures and Magnetic and Thermal Properties of AI[MIII(HPO3)2] (A=K, NH4, Rb and M=V, Fe). J. Solid State Chem. 2013, 198, 295–302.

(14)

Mandal, S.; Natarajan, S. Synthesis, Structure, and Polymorphism Studies in Amine-Templated OpenFramework Zinc Phosphites. Inorg. Chem. 2008, 47, 5304– 5313.

(15)

Verbaere, A.; Marchand, R.; Tournoux, M. Localisation Du Doublet Solitaire Dans Les Composés Oxygènés Cristallisés Du Thallium I. J. Solid State Chem. 1978, 23, 383–390.

(16)

Henry, M. Nonempirical Quantification of Molecular Interactions in Supramolecular Assemblies. ChemPhysChem 2002, 3, 561–569.

(17)

Henry, M. Non-Covalent Interactions in Solid-State Molecular Tectonics. In Advances in quantum chemical bonding structures; Putz, M. V., Ed.; Transworld Research Network: Kerala, India, 2008; pp. 153–211.

(18)

Becke, A. D. Density-Functional Thermochemistry. III. The Role of Exact Exchange. J. Chem. Phys. 1993, 98, 5648–5652.

(19)

Lee, C.; Yang, W.; Parr, R. G. Development of the ColleSalvetti Correlation-Energy Formula into a Functional of the Electron Density. Phys. Rev. B 1988, 37, 785–789.

(20)

Passos, O.; Fernandes, P. A.; Ramos, M. J. Theoretical Insights into the Catalytic Mechanism of βHexosaminidase. Theor. Chem. Acc. 2011, 129, 119–129.

(21)

Foster, J. P.; Weinhold, F. Natural Hybrid Orbitals. J. Am. Chem. Soc. 1980, 102, 7211–7218.

(22)

Poienar, M.; Maignan, A.; Sfirloaga, P.; Malo, S.; Vlazan, P.; Guesdon, A.; Lainé, F.; Rouquette, J.; Martin, C. Polar Space Group and Complex Magnetism in Ni11□(HPO3)8(OH)6: Towards a New Multiferroic Material? Solid State Sci. 2015, 39, 92–96.

(23)

Marcos, M. D.; Amorós, P.; Beltrán-Porter, A.; MartinezManez, R.; Attfield, J. P. Novel Crystalline Microporous Transition-Metal Phosphites M11(HPO3)8(OH)6 (M = Zn, Co, Ni). X-Ray Powder Diffraction Structure Determination of the Cobalt and Nickel Derivatives. Chem. Mater. 1993, 5,

121–128. (24)

Gao, Y.; Zhao, J.; Run, Z.; Zhang, G.; Pang, H. Microporous Ni11(HPO3)8(OH)6 Nanocrystals for High-Performance Flexible Asymmetric All Solid-State Supercapacitors. Dalt. Trans. 2014, 43, 17000–17005.

(25)

Attfield, M. P.; Morris, R. E.; Cheetham, A. K. Synthesis and Structures of Two Isostructural Phosphites, Fe11(HPO3)8(OH)6 and Mn11(HPO3)8(OH)6. Acta Crystallogr. 1994, C50, 981–984.

(26)

Amorós, P.; Marcos, M. D.; Roca, M.; Beltrán-Porter, A.; Beltrán-Porter, D. Synthetic Pathways for New Tubular Transition Metal Hydroxo- and Fluoro-Selenites: Crystal Structures of M12(X)2(SeO3)8(OH)6 (M=Co2+, Ni2+; X=OH−, F−). J. Solid State Chem. 1996, 126, 169–176.

(27)

Giester, G. The Crystal Structure of Fe2(SeO3)3∙H2O. J. Solid State Chem. 1993, 103, 451–457.

(28)

Giester, G.; Pertlik, F. Synthesis and Crystal Structure of iron(III) selenate(IV) Trihydrate, Fe2(SeO3)3∙3H2O. J. Alloys Compd. 1994, 210, 125–128.

(29)

Hawthorne, F. C. The Crystal Structure of Mandarinoite, Fe3+2Se3O9∙6H2O. Can. Mineral. 1984, 22, 475–480.

(30)

Fan, J.; Yee, G. T.; Wang, G.; Hanson, B. E. Syntheses, Structures, and Magnetic Properties of Inorganic−Organic Hybrid Cobalt(II) Phosphites Containing Bifunctional Ligands. Inorg. Chem. 2006, 45, 599–608.

(31)

Ensling, J.; Guetlich, P.; Schmidt, R.; Kniep, R. Ferric Phosphite: Dimers of Face-Sharing FeIIIO6 Octahedra. Crystal Structure Redetermination, Moessbauer Spectra, Magnetic Susceptibility, and Heat Capacity Data. Inorg. Chem. 1994, 33, 3595–3597.

(32)

Kahn, O. Molecular Magnetism; WILEY-VCH Verlag: Weinheim, 1993.

(33)

Hu, S.; Johnsson, M.; Law, J. M.; Bettis, J. L.; Whangbo, M.H.; Kremer, R. K. Crystal Structure and Magnetic Properties of FeSeO3F—alternating Antiferromagnetic S = 5/2 Chains. Inorg. Chem. 2014, 53, 4250–4256.

(34)

Ben Yahia, H.; Gaudin, E.; Darriet, J.; Banks, M.; Kremer, R. K.; Villesuzanne, A.; Whangbo, M.-H. Synthesis, Crystal Structure, Magnetic Properties, and Electronic Structure of the New Ternary Vanadate CuMnVO4. Inorg. Chem. 2005, 44, 3087–3093.

(35)

Whangbo, M.-H.; Koo, H.-J.; Dai, D. Spin Exchange Interactions and Magnetic Structures of Extended Magnetic Solids with Localized Spins: Theoretical Descriptions on Formal, Quantitative and Qualitative Levels. J. Solid State Chem. 2003, 176, 417–481.

(36)

Dudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P. Electron-Energy-Loss Spectra and the Structural Stability of Nickel Oxide: An LSDA+U Study. Phys. Rev. B 1998, 57, 1505–1509.

(37)

Zarestky, J. L.; Vaknin, D.; Chakoumakos, B. C.; Rojo, T.; Goñi, A.; Barberis, G. E. Antiferromagnetism in αLi3Fe2(PO4)3. J. Magn. Magn. Mater. 2001, 234, 401–408.

(38)

Andersson, A. S.; Kalska, B.; Jönsson, P.; Häggström, L.; Nordblad, P.; Tellgren, R.; Thomas, J. O. The Magnetic Structure and Properties of Rhombohedral Li3Fe2(PO4)3. J. Mater. Chem. 2000, 10, 2542–2547.

(39)

Long, G.J. A Mössbauer Effect And Magnetic Study of Fe2(SO4)3 and Fe2(MoO4)3, Two L-Type Ferrimagnets. In



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Chemical Mössbauer Spectroscopy; Herber, R.H., Ed.; Springer US: New-York, 1984; pp. 95–111.

Table of Contents (TOC)


Page 8 of 8

Bonding Scheme, Hydride Character, and Magnetic Paths of (HPO3)2

Recommend Documents