ElectrophilicâNucleophilic Dualism of Nickel(II) toward NiÂ·Â·Â·I

Article pubs.acs.org/IC

Cite This: Inorg. Chem. XXXX, XXX, XXX-XXX

Electrophilic−Nucleophilic Dualism of Nickel(II) toward Ni···I Noncovalent Interactions: Semicoordination of Iodine Centers via Electron Belt and Halogen Bonding via σ‑Hole Zarina M. Bikbaeva,† Daniil M. Ivanov,† Alexander S. Novikov,† Ivan V. Ananyev,◊ Nadezhda A. Bokach,*,† and Vadim Yu. Kukushkin*,† †

Saint Petersburg State University, Universitetskaya Nab. 7/9, 199034 Saint Petersburg, Russian Federation A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova St., 28, 119991 Moscow, Russian Federation

◊

S Supporting Information *

ABSTRACT: The nitrosoguanidinate complex [Ni{NHC(NMe2)NN(O)}2] (1) was cocrystallized with I2 and sym-trifluorotriiodobenzene (FIB) to give associates 1·2I2 and 1·2FIB. Structures of these solid species were studied by XRD followed by topological analysis of the electron density distribution within the framework of Bader’s approach (QTAIM) at the M06/DZP-DKH level of theory and Hirshfeld surface analysis. Our results along with inspection of XRD (CCDC) data, accompanied by the theoretical calculations, allowed the identification of three types of Ni···I contacts. The Ni···I semicoordination of the electrophilic nickel(II) center with electron belt of I2 was observed in 1·2I2, the metal-involving halogen bonding between the nucleophilic nickel(II)-dz2 center and σ-hole of iodine center was recognized and confirmed theoretically in the structure of [FeNi(CN)4(IPz)(H2O)]n (IPz = 4-N-coordinated 2-I-pyrazine), whereas the arrangement of FIB in 1·2FIB provides a boundary case between the semicoordination and the halogen Ni···I bondings. In 1·2I2 and 1·2FIB, noncovalent interactions were studied by variable temperature XRD detecting the expansion of noncovalent contacts with preservation of covalent bond lengths upon the temperature increase from 100 to 300 K. The nature and energies of all identified types of the Ni···I noncovalent interactions in the obtained (1·2I2 and 1·2FIB) and in the previously reported ([FeNi(CN)4(IPz)(H2O)]n, [NiL2](I3)2·2I2 (L = o-phenylene-bis(dimethylphosphine), [NiL]I2 (L = 1,4,8,11-tetra-azacyclotetradecane), Ni(en)2]n[AgI2]2n (en = ethylenediamine), and [NiL](ClO4) (L = 4-iodo-2-((2-(2-(2-pyridyl)ethylsulfanyl)ethylimino)methyl)-phenolate)) structures were studied theoretically. The estimated strengths of these Ni···I noncovalent contacts vary from 1.6 to 4.1 kcal/mol and, as expected, become weaker on heating. This work is the first emphasizing electrophilic−nucleophilic dualism of any metal center toward noncovalent interactions.

1. INTRODUCTION The study of noncovalent interactions has undergone impressive growth in the past five years, warranting a special issue of Chemical Reviews (Issue 9, 2016) dedicated exclusively to this subject. Various types of intermolecular contacts such as hydrogen-,1 halogen-,1b,c,2 chalcogen-,1b,c,3 pnictogen-,1b,c and tetrel-bonding,1b,4 tetrel-like σ-hole interactions involving Pb2+,5 π-stacking,6 and lp···π7 interactions are efficiently used as tools in crystal engineering and in design of functional materials. In most reported cases, only typical non-metal atoms bearing lone pairs (e.g., O, N, S) or non-metal atoms exhibiting expressed σ-holes (e.g., heavy halogens) behave as partners in the supramolecular organization. Noncovalent interactions including metal centers (Figure 1) are substantially less studied than non-metal systems, with most work devoted to metallophilic interactions,8 hydrogen bonding,9 anagostic10 and agostic interactions,11 and metal−π interactions.12 Recent applications of metallophilic interactions © XXXX American Chemical Society

include design of smart materials with unique luminescent and conducting properties13 and self-assembly.14 Anagostic and agnostic interactions play an active role in catalysis, and these noncovalent contacts are often used to activate inert C−H bonds and thus facilitate new reactions.15 Other less common types of contacts with metal centers include halogen bonding (for our recent work, see refs 8 and 16, and for discussion, see section 2.2 below) and finally the semicoordination bond17 (Figure 1). Semicoordination bond, the noncovalent analog of the coordination bond, is uncommon but recognized, particularly for metal centers with labile coordination numbers such as copper(II) (for recent works, see ref 18). This phenomenon is incomparably less studied than the typical coordination bond, with only ca. 130 references Received: September 6, 2017

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DOI: 10.1021/acs.inorgchem.7b02224 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry

mixtures of 1 with I2 or FIB, taken in a 1:2 molar ratio, from a CHCl3 solution at RT. In 1·2I2 and 1·2FIB, all corresponding geometrical parameters (Table S1, Supporting Information) of the nitrosoguanidinate complex are similar, within 3σ, with those of free complex 1 depicted in Figure 2. In these two associates, we recognized yet unreported Ni···I contacts. Apart from 1 (Figure 2; R1/R2 = Me/Me), we also employed other (nitrosoguanidinate)NiII complexes as XB acceptors, namely, R1/R2 = Me/Ph and (CH2)5, and on the other hand I2, FIB, 1,2- and 1,4-diiodotetrafluorobenzenes, and tetraiodoethylene as XB donors. In varieties of the obtained associates, we observed some other examples of the unconventional C−I··· N and C−I···O contacts including both terminal and bifurcated XBs (these observations will be published separately), but iodine···nickel(II) intramolecular interactions were found only in 1·2I2 and 1·2FIB, and these two structures will be discussed herein. 2.2. Nickel(II) Center as an Electrophile: Semicoordination Bonds between Ni II and Iodine Centers. 2.2.1. Crystal and Molecular Structures of 1·2I2 at 100 K. In 1·2I2, one molecule of 1 is surrounded by eight molecules of I2, involved in four different pairs of intermolecular contacts (Figures 3 and 4, Tables 1−3). One pair of I2 forms short Figure 1. Types of interactions with metal centers.

returned using the query “semicoordination bond” in CAS SciFinder, compared to 90 000 for “coordination bond”. Owing to our interest in noncovalent interactions (for recent works, see refs 16 and 19) and in particular in metal-involving halogen bonding,16a we studied the association of our recently prepared (nitrosoguanidinate)NiII species20 with various iodine-containing halogen bond (commonly abbreviated as XB) donors. The obtained experimental and theoretical results along with a literature search and CCDC data analysis revealed that nickel(II) centers, depending on the ligand environment and the nature of the iodine donor, may exhibit electrophilic− nucleophilic dualism and either form a semicoordination bond, displaying electrophilic properties, or behave as a halogen bond acceptor via their dz2 orbital, thus displaying nucleophilic nature. All these findings, including the recognition of the cooperative semicoordination−XB effects at nickel(II) centers, are detailed in sections that follow.

Figure 3. Surroundings of complex 1 in 1·2I2.

contacts Ni1···I2S with the metal center and also provides lp(I)···πguanidine interactions (Figure 4a; for a review on lp···π interactions see ref 21). The other two I2 are linked with both nitrosoguanidine ligands via bifurcated C−I···(N−NO) interactions (b). The remaining two I2 form the N3−H3··· I2S hydrogen bond combined with the I2S···O1 contact (c). Finally, C2−H2B···I2S hydrogen bonds were identified. The Ni1···I2S−I1S (3.5130(5) Å) separation (type a) is shorter than the sum of Bondi’s vdW radii (RvdW(Ni) + RvdW(I) = 3.61 Å) and the ∠(Ni1···I2S−I1S) angle is 94.723(11)°. These parameters indicate that the contact between the electron belt of an iodine center and the nickel(II) center can be treated as a semicoordination bond.17 The other iodine atom of the same molecule forms a contact between the electron belt and C atom of the guanidine fragment (I1S··· Cguanidine distance is 3.598(5) vs 3.68 Å for the Bondi’s vdW radii sum, ∠(C1···I1S−I2S) angle is 82.13(6)°) that can be attributed to lp(I)···πguanidine interaction (a). The distances I1S···N2 and I1S···O1 (type b, 3.283(3) and 2.622(3) Å, correspondingly) are substantially shorter than the appropriate sums of Bondi’s vdW radii (RvdW(I) + RvdW(N) = 3.53 and RvdW(I) + RvdW(O) = 3.50 Å); the corresponding angle ∠(I2S−I1S···O1) = 172.81(6)° is close to 180°, and hence, the I2S−I1S···O1 contact can be treated as XB in accord with the IUPAC criteria.23 At the same time, the ∠(I2S−I1S··· N2) angle (145.58(7)°) sufficiently deviates from 180°.

2. RESULTS AND DISCUSSION 2.1. Synthesis of Two Associates Featuring Ni···I Interactions. The nitrosoguanidinate complex [Ni{NH C(NMe2)NN(O)}2] (1; Figure 2) was synthesized by the reaction between MeC(NOH)NH2, NCNMe2, and NiCl2 in MeOH as we described earlier.20 Associates 1·2I2 and 1·2FIB (FIB is sym-trifluorotriiodobenzene, C6F3I3) were obtained by the slow crystallization of

Figure 2. Molecular structure and graphical representation (R1/R2 = Me/Me) of free 1 employed for this work as XB acceptor. B


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Inorganic Chemistry

Figure 4. Types of short contacts in 1·2I2. The color scheme is taken from Politzer’s work.22

Table 1. Parameters of the R−I···X (X = N, O) XBs in 1·2I2 and 1·2FIB at 100 K structure 1·2I2

1·2FIB

a

R−I···X

d(I···X), Å

R

∠(R−I···X), deg

Eintb

Eintc

I2S−I1S···O1 I1S−I2S···O1 I2S−I1S···N2 C1S−I1S···O1 C1S−I1S···N2 comparisona

2.622(3) 3.361(3) 3.283(3) 3.003(3) 3.286(4) 3.50 (I···O) 3.53 (I···N)

0.75 0.96 0.93 0.86 0.93 1.00

172.81(6) 160.44(5) 145.58(7) 170.80(15) 148.91(15) 180

8.8 1.3 2.5 3.5 2.2

7.3 1.6 2.4 3.5 2.2

Comparison between the sum of Bondi’s27 vdW radii and conventional halogen bond angle. bEint = −V(r)/2.28 cEint = 0.429G(r).29

Table 2. Parameters of the Ni···I−R (R = I, CAr) Interactions in 1·2I2 and 1·2FIB at 100 K

a

structure

Ni···I−R

d(Ni···I), Å

R

∠(Ni···I−R), deg

Eintb

Eintc

1·2I2 1·2FIB

Ni1···I2S−I1S Ni1···I3S−C5S comparisona

3.5130(5) 3.3886(5) 3.61 (Ni···I)

0.97 0.94 1.00

94.723(11) 142.51(14) 90

2.2 2.5

2.2 2.2


Table 3. Parameters of the C···I−R (R = I, CAr) (lp(I)···π) Interactions in 1·2I2 and 1·2FIB at 100 K

a

structure

C···I−R

d(C···I), Å

R

∠(Ni···I−R), deg

Eintb

Eintc

1·2I2 1·2FIB

C1···I1S−I2S C6···I2S−C3S comparisona

3.598(5) 3.598(5) 3.68 (C···I)

0.98 0.98 1.00

82.13(6) 73.73(16) 90

1.3 1.3

1.3 1.3


However, diiodine demonstrates a relatively large σ-hole,24 so the I2S−I1S···N2 interaction still may belong to XB. Indeed, the bifurcation of the I−I···(N−NO) interaction was confirmed theoretically (see section 2.3) and DFT calculations suggest that the contribution of the I···O interaction into XB is sufficiently stronger than that of the I···N. To the best of our knowledge, it is the shortest I−I···O XB involving I2 so far reported. A literature search for the bifurcated XB between any iodine centers and oxygen and nitrogen centers revealed no I··· (N{spacer}O) moieties (Figure 5). However, interactions of an iodine atom with two oxygen2,25 and two nitrogen2a,c,26 centers are known. One iodine atom of I2 molecule (type c) simultaneously forms a XB with the O1 atom of 1 with I2S···O1 distance 3.361(3) Å (RvdW(O) + RvdW(I) = 3.50 Å) and the ∠(I1S− I2S···O1) angle 160.44(5)° and a HB with the H atom of the NH group of 1; the N3···I2S distance is 3.926(3) Å. Although we considered separately these three types of weak interactions, in fact, each I2 molecule in the crystal structure is involved in all a−c type contacts (Figure 4): one I center exhibits both a and c type contacts, whereas the other I center is

Figure 5. Types of bifurcated XBs of an iodine center with O and N atoms.

involved in b type contacts (Figure 4). The crystal structure of 1·2I2 is composed of alternate wavelike layers of the complex and iodine molecules (view along a axis; Figure 6), or if viewed along b axis (Figure 7), it is comprised of 2D-layers formed by the planar nickel(II) complexes and iodine molecules, which are almost coplanar to these complexes. All molecules within one layer form the I1S−I2S···O1 contact, the I2S−I1S···(N2− N1O1) bifurcated contact, and the N−H···I hydrogen bond, whereas contacts between neighboring layers are represented by the Ni1···I2S−I1S and lp(I)···πguanidine interactions. 2.2.2. Variable Temperature XRD Study of 1·2I2. These studies were carried out for a crystal of 1·2I2 in order to C


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Figure 6. View along a axis of 1·2I2 (100).

Figure 7. View along b axis of 1·2I2 (010).

The structural analysis of the obtained data (Tables S4−S7) indicates that the heating leads only to linear and reversible changes of the intermolecular distances, whereas the covalent bond lengths and interaction angles, including those for intermolecular contacts, remain almost the same. In 1·2I2, the most significant variation was observed for the lp(I)···π contact (by 0.11 Å upon temperature increase from 100 to 300 K); the I1S···C1 distance exceeds the Bondi’s vdW radii sum for corresponding atoms above 250 K (3.6854(3) Å

establish temperature dependence of the intermolecular interactions and to get a deeper insight into dynamic features of the crystal packing. The thermally induced transformation of supramolecular bonding was especially interesting taking into account that this kind of bonding dynamics has been recently observed for bifurcated metal-involving XBs.16a For this purpose, VTXRD experiments for the same single-crystal of 1·2I2 were performed at 100, 150, 200, 250, and 300 K. D


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2.2.3. Theoretical Study on Identification of the Semicoordination Bond. In order to confirm or disprove the hypothesis on the existence of the discussed above noncovalent interactions in 1·2I2 and to quantify their energies from a theoretical viewpoint, in addition to the structural study, we carried out a detailed computational study at the M06/DZPDKH level of theory and performed topological analysis of the electron density distribution within the framework of Bader’s theory (QTAIM method)30 for model supramolecular cluster (Table S9). This approach has already been successfully used by us for studies of different noncovalent interactions (e.g., hydrogen, halogen, and chalcogen bonding, metallophilic interactions, stacking) and properties of coordination bonds in various transition metal complexes.16a,19b−f,31 Results are summarized in Table 4, the contour line diagrams of the Laplacian distribution ∇2ρ(r), bond paths, and selected zeroflux surfaces are shown in Figure 9. To visualize the studied noncovalent interactions, reduced density gradient (RDG) analysis32 was carried out, and RDG isosurfaces were plotted. The QTAIM analysis demonstrates the presence of appropriate bond critical points (BCPs) (3, −1) for all noncovalent interactions in 1·2I2 listed in Table 4. The low magnitude of the electron density (0.002−0.033 hartree), positive values of the Laplacian (0.010−0.100 hartree), and close to zero (−0.002 to 0.001 hartree) energy density in these BCPs are typical for noncovalent interactions. We have defined energies for these contacts according to the procedures proposed by Espinosa et al.28 and Vener et al.29 (Table 4), and one can state that all studied noncovalent interactions, except I···O (bifurcate), are relatively weak (0.3−2.5 kcal/mol), whereas the I···O (bifurcate) contact is rather strong (7.3−8.8 kcal/mol). As can be inferred from analysis of these values, the I−I···O XB is the strongest among all noncovalent interactions detected in this associate, and these contacts may play a crucial role in the definition of I2 position around the complex. The C···I (lp···π) interactions are approximately two times weaker than the Ni···I contacts. The balance between the Lagrangian kinetic energy, G(r), and potential energy density, V(r), at the BCPs (3, −1) reveals the nature of these interactions: if the ratio −G(r)/V(r) > 1 is satisfied, then the nature of the

vs RvdW(I) + RvdW(C) = 3.68 Å). Notably this change of the I1S···C1 distance is also reversible. The only geometry criteria, however, cannot serve as undoubted evidence of the thermally induced transformation of these intermolecular interactions. The performed calculations supported the preservation of each type of the noncovalent interactions in 1·2I2 upon temperature increase from 100 to 300 K. An anomalous, albeit small, change was established for the I2S···O1 XB in 1·2I2 upon heating from 100 to 300 K, when the corresponding distance shortens 0.03 Å; the shortening of this distance can be explained by an effect of its environment (Figure 8). According to the comparison of intermolecular

Figure 8. Environment of the I2S···O1 XB in 1·2I2.

distance and estimations of bonding energies (see below), the I2S···O1 interaction is the weakest one among all three I···O XBs in 1·2I2 and 1·2FIB (see section 2.4.1 for discussion of its crystal packing). In turn, the O1 atom participates in the stronger I1S···O1 XB (weakens significantly upon heating, see above), whereas the I2S atom forms a HB with the NH fragment (the N···I distance lengthens on 0.03 Å on heating from 100 to 300 K). Accordingly, the joint contribution of these interactions can overcome the forces linking the I2S and O1 atoms together.

Table 4. Values of the Density of All Electrons [ρ(r)], Laplacian of Electron Density [∇2ρ(r)], Energy Density [Hb], Potential Energy Density [V(r)], and Lagrangian Kinetic Energy [G(r)] (hartree) at the Bond Critical Points (3, −1), Corresponding to Different Noncovalent Interactions in 1·2I2 and 1·2FIB, and Bond Lengths [l (Å)] as well as Energies for These Contacts [Eint (kcal/mol)], Defined by Two Approaches contact

ρ(r)

∇2ρ(r)

Hb

V(r)

G(r)

Einta

Eintb

l

−0.028 −0.008 −0.004 −0.004 −0.001 −0.004 −0.007

0.027 0.009 0.006 0.005 0.002 0.005 0.008

8.8 2.5 1.3 1.3 0.3 1.3 2.2

7.3 2.4 1.6 1.3 0.5 1.3 2.2

2.62 3.28 3.36 3.05 4.42 3.60 3.51

−0.011 −0.007 −0.005 −0.004 −0.008

0.013 0.008 0.006 0.005 0.008

3.5 2.2 1.6 1.3 2.5

3.5 2.2 1.6 1.3 2.2

3.00 3.29 3.82 3.60 3.39

1·2I2 I···O (bifurcate) I···N (bifurcate) I···O H···I I···I C···I (lp···π) Ni···I

0.033 0.011 0.007 0.007 0.002 0.007 0.011

0.100 0.041 0.029 0.023 0.010 0.027 0.032

−0.002 0.001 0.001 0.001 0.001 0.001 0.001

I···O (bifurcate) I···N (bifurcate) C−I···I C···I (lp···π) I···Ni

0.016 0.011 0.008 0.007 0.012

0.055 0.039 0.029 0.025 0.033

0.001 0.001 0.001 0.001 0.000

1·2FIB

a

Eint = −V(r)/2.28 bEint = 0.429G(r).29 E


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Figure 9. Contour line diagrams of the Laplacian distribution ∇2ρ(r), bond paths, and selected zero-flux surfaces (top) and RDG isosurfaces (bottom) referring to different noncovalent interactions in 1·2I2. Bond critical points (3, −1) are shown in blue, nuclear critical points (3, −3) in pale brown, and ring critical points (3, +1) in orange. Length units in Å, RDG isosurface values are given in hartree.

Table 5. Values of the Density of All Electrons [ρ(r)], Laplacian of Electron Density [∇2ρ(r)], Energy Density [Hb], Potential Energy Density [V(r)], and Lagrangian Kinetic Energy [G(r)] (hartree) at the Bond Critical Points (3, −1), corresponding to Ni···I, I···Ni, and lp···π Interactions in 1·2I2 and 1·2FIB at the Different Temperatures, and bond lengths [l (Å)] as well as Energies for these Contacts [Eint (kcal/mol)], defined by Two Approaches temp (K)

a

ρ(r)

∇2ρ(r)

Hb

100 150 200 250 300

0.011 0.011 0.011 0.010 0.010

0.033 0.032 0.031 0.031 0.030

0.001 0.001 0.001 0.001 0.001

100 150 200 250 300

0.007 0.007 0.007 0.006 0.006

0.027 0.026 0.025 0.024 0.023

0.001 0.001 0.001 0.001 0.001

100 150 200 250 300

0.012 0.012 0.011 0.011 0.011

0.033 0.033 0.032 0.031 0.030

0.000 0.000 0.000 0.000 0.001

V(r) 1·2I2 Ni···I −0.007 −0.007 −0.007 −0.006 −0.006 lp···π −0.004 −0.004 −0.003 −0.003 −0.003 1·2FIB I···Ni −0.008 −0.008 −0.007 −0.007 −0.006

G(r)

Einta

Eintb

0.008 0.007 0.007 0.007 0.007

2.2 2.2 2.2 1.9 1.9

2.2 1.9 1.9 1.9 1.9

3.51 3.52 3.54 3.55 3.57

0.005 0.005 0.005 0.005 0.004

1.3 1.3 0.9 0.9 0.9

1.3 1.3 1.3 1.3 1.1

3.60 3.63 3.66 3.69 3.71

0.008 0.008 0.008 0.007 0.007

2.5 2.5 2.2 2.2 1.9

2.2 2.2 2.2 1.9 1.9

3.39 3.41 3.43 3.45 3.47

l

(C···I), (C···I), (C···I), (C···I), (C···I),

3.67 3.69 3.71 3.73 3.76

(N···I) (N···I) (N···I) (N···I) (N···I)

Eint = −V(r)/2.28 bEint = 0.429G(r).29

interaction is purely noncovalent; in the case of −G(r)/V(r) < 1, some covalent component is involved.33 Based on this criterion, one can state that covalent contribution is absent in all above discussed contacts, except I···O (bifurcate).

The analysis of the results of DFT calculations and topological analysis of the electron density distribution within the formalism of Bader’s theory (QTAIM method) for the Xray structures of 1·2I2 at different temperatures gives the idea F


3.3416(2) 3.3052(12) 3.5316(11) 3.406(3) and 3.423(3) 3.5506(17) 3.453(2) and 3.2937(17) 3.0135(8), 3.0656(9), and 3.176(2) 3.4915(15)

3.5644(18) 3.4702(17) 3.5130(5) 3.3886(5)

Ni···(I−) Ni···(I−) Ni···(I−) Ni···(I−) Ni···(I−) Ni···(I−) Ni···(I−) Ni···(I−I−I−) Ni···(I−[Ag]) Ni···(I−CAr) Ni···(I−CAr) Ni···(I−I) Ni···(I−CAr)

[NiL]I2·EtOH·H2O (L = 1,4,8,11-tetra-azacyclotetradecane)

[NiL]I2 (L = 1,4,8,11-tetra-azacyclotetradecane)

[NiL]I2 (L = (C-meso-5,5,7,12,12,14-hexamethylcyclotetradecane)

[Ni(HL1)](I3)2(I)·H2O (L1 = 6,6-bis(4-amino-2-azabutyl)-l,4-diazacycloheptane)

[Ni2L(H2O)2]I2 (L = 10,22-dimethyl-3,6,14,18-tetra-azatricyclo(18.3.1.18,12)pentacosa-1(24),8,10,12(25),20,22-hexaen-24,25-diolate) [Ni2L]I4·3H2O (L = (μ2-7,7′-(propane-1,3-diyl)bis(3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene) KI·[NiL] (H2L = N,N′-(3-methoxysalicylidene)propane-1,3-diamine)

[NiL2](I3)2·2I2 (L = o-phenylene-bis(dimethylphosphine))

[Ni(en)2]n[AgI2]2n (en = ethylenediamine)

[NiL](ClO4) (L = 4-iodo-2-((2-(2-(2-pyridyl)ethylsulfanyl)ethylimino)methyl)phenolate) [FeNi(CN)4(IPz)(H2O)]n (IPz = 4-N-coordinated 2-I-pyrazine)

1·2I2

1·2FIB

E3

E4

E5

E6

E7

E10

E11

E12

E13

E14

E15

G

142.51(14)

94.723(11)

177.8(4)

94.19(14)

95.87(9) and 161.41(3)

118.44(4)

∠(Ni···I−X), deg 1269566/ TETFUT 1283555/ VIGBIW 1119027/ CAFHUM 1187804/ JIZTUH 1233884/ PIMHAU 1186603/ JIMNIC 1231443/ PETCOG 601872/ CEQVEA 144970/ XEDCIS 1129505/ CONRUS 1219657/ NIENIA 198418/ UNAVEK 1480684/ AMIJAJ

CCDC no./ CSD RefCode

A

A

B

B

B

B

A

A

B

A

B

A

B

commentsa

ref

this work this work

49

48

47

46

45

44

43

42

41

40

39

38

37

a A indicates that in the original work, the short Ni···I contact was not found and it was verified upon our processing of the XRD(CCDC) data. B indicates that in the original work, the short Ni···I contacts were recognized but were not attributed to semicoordination bond and were denoted as “weak interactions”, “negligible binding”, “coordinative bonding” etc.

E9

3.508(3)

3.557(3)

Ni···(I−)

[Ni(N,N′,S,S′)-L]I2 (L = 1,5-bis(methylthioethyl)-1,5-diazacyclo-octane)

E2

E8

3.542(2)

Ni···(I−)

[Ni(N,N′,S,S′)-L]I2 (L = (N,N′-bis(5-hydroxy-3-thiopentyl)-1,5-diazacyclo-octane))

d(Ni−I), Å

E1

contact Ni···I

structure

entries

Table 6. Ni···I Contacts Verified upon Our Processing of CCDC Data

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Inorganic Chemistry

Figure 10. Structures of model supramolecular clusters CONRUS, JIZTUH, NIENIA, and UNAVEK.

Table 7. Values of the Density of All Electrons [ρ(r)], Laplacian of Electron Density [∇2ρ(r)], Energy Density [Hb], Potential Energy Density [V(r)], and Lagrangian Kinetic Energy [G(r)] (Hartree) at the Bond Critical Points (3, −1), Corresponding to Ni···I Semicoordination Bonds in CONRUS, JIZTUH, NIENIA, and UNAVEK, and Bond Lengths [l (Å)] as well as Energies for These Contacts [Eint (kcal/mol)], Defined by Two Approaches

a

model structure

ρ(r)

∇2ρ(r)

Hb

V(r)

G(r)

Einta

Eintb

l

CONRUS JIZTUH NIENIA UNAVEK

0.013 0.018 0.012 0.011

0.032 0.037 0.028 0.030

0.000 −0.002 0.000 0.001

−0.008 −0.013 −0.007 −0.006

0.008 0.011 0.007 0.007

2.5 4.1 2.2 1.9

2.2 3.0 1.9 1.9

3.491 3.305 3.508 3.564

Eint = −V(r)/2.28 bEint = 0.429G(r).29

that the thermal expansion has little effect on the electron density properties and strengths of the Ni···I and lp(I)···π contacts, namely, appropriately estimated noncovalent interaction energies range from 2.2 to 1.9 kcal/mol and from 1.3 to 0.9 kcal/mol, respectively. The only significant point is that upon the increase of temperature, the bond path for lp(I)···π interactions changes from C···I to N···I (Table 5 and MP4 files are given in Supporting Information). 2.2.4. Overlooked Ni···I Semicoordination Bonds. As indicated in the Introduction, only one example34 of a nickelinvolving semicoordination bond, Ni···Cl, was described in the literature. Another work35 reports that the solid heterodinuclear complexes [NiLLnIII(NO3)3] [H2L = N,N′-ethylenebis(3ethoxysalicylaldiimine); Ln = Ce, Nd, Eu, Tb, Er] exhibit semicoordination NiII···(ONO2) bonds that fall in the 3.382− 3.424 Å range. These values are substantially larger than the Bondi’s (RvdW(Ni) + RvdW(O) = 3.15 Å) sum and these simple comparisons make the identification of semicoordination uncertain. Our inspection of the relevant literature and processing of available CCDC data indicate that the phenomenon of semicoordination in general and the semicoordination of iodine to nickel(II) centers might be substantially more common. We inspected the CCDC database for availability of these overlooked contacts. Our inspection verified more than 50 structures featuring Ni···X (X = halide, O, N) contacts that can be attributed to semicoordination bonds. Focusing, in particular, on Ni···I interactions where the distance between atoms is less than the sum of Bondi’s van der Waals radii (3.61 Å)27 and greater than the normal Ni−I bond (2.67(15) Å),36

we found in CCDC several structures that fall into this interval (Table 6). In the original works E1, E3, E5, and E8−E11, the short Ni···I contacts were recognized, but they were not attributed to semicoordination bonds and only denoted as “weak interactions”, “negligible binding”, “loosely bound centers”, etc. In the other cases (E2, E4, E6, E7, E12, and E13), short Ni···I contacts were not found, and they were verified upon our inspection of the XRD (CCDC) data. For four representative examples of the overlooked Ni···I semicoordination bonds (in JIZTUH [Ni···(I−)], CONRUS [Ni···(I−I−I−)], NIENIA [Ni···(I−[Ag])], and UNAVEK [Ni···(I−CAr)]) (Figure 10), we carried out detailed computational study at the M06/DZP-DKH level of theory and performed topological analysis of the electron density distribution within the formalism of Bader’s theory (QTAIM method).30 Appropriate structures of model supramolecular clusters CONRUS, JIZTUH, NIENIA, and UNAVEK are given in Figure 10 and Table S9 (Supporting Information). Results are presented in Table 7 and Figure 11. The QTAIM analysis demonstrates the presence of BCPs for the Ni···I semicoordination bonds in all four model clusters. The values of electron density (0.011−0.018 hartree), Laplacian of electron density (0.028−0.037 hartree), and energy density (−0.002 to 0.001 hartree) in these BCPs are typical for noncovalent interactions. The contacts Ni···I in JIZTUH have some covalent component, whereas in CONRUS, NIENIA, and UNAVEK, they are purely noncovalent. The estimated strengths of Ni···I semicoordination bonds in CONRUS, JIZTUH, NIENIA, and UNAVEK are 2.2−2.5, 3.0−4.1, 1.9− H


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Inorganic Chemistry

Figure 11. Contour line diagrams of the Laplacian distribution ∇2ρ(r), bond paths, and selected zero-flux surfaces (left) and RDG isosurfaces (right) referring to Ni···I semicoordination bonds in CONRUS, JIZTUH, NIENIA, and UNAVEK (from top to bottom). Bond critical points (3, −1) are shown in blue, nuclear critical points (3, −3) in pale brown, ring critical points (3, +1) in orange, and cage critical points (3, +3) in light green. Length units in Å, RDG isosurface values are given in hartree.

2.2, and 1.9 kcal/mol, respectively. Thus, one can conclude that the Ni···I semicoordination bonding is not unusual, albeit overlooked, phenomenon in the coordination chemistry of nickel(II).50 2.3. Nickel(II) Center as a Nucleophile: Halogen Bonding of Iodine Center via Its σ-Hole. After the identification of the Ni···I semicoordination bond and observation of the intermediate interaction between semicoordination and halogen bonding (see section 2.4 later), we attempted to identify a pure halogen bond between the nickel(II) center and iodine, and we analyzed available CCDC

structures taking into account the known IUPAC criteria for XB.51 According to the IUPAC definition, XB51 is the real R−X···Y (X = halogen) contact, when, first, the interatomic distance between X and an appropriate nucleophilic atom of Y (e.g., Y is iodine) is less than the sum of their vdW radii and, second, the R−X···Y angle is close to 180° (exceptions from linearity have been reviewed by Rissanen52 and also analyzed in our previous work16a). 2.3.1. Identification of Halogen Bonding in the Structure of AMIJAJ. Upon our inspection of CCDC under the angle of I


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Inorganic Chemistry

Our examination of the literature revealed few experimental studies devoted to XBs with metal centers, either which were not considered as XBs or of which the geometrical parameters fulfill only one of the two aforementioned structural IUPAC criteria for XB. In only a few cases, the identification of XB with metal centers was supported by both IUPAC criteria,51 and thus, weak contacts were observed between some d8-metal systems such as platinum(II)53 (for our work, see ref 16a) and rhodium(I)54 and iodine centers. Our processing of the available XRD data for AMIJAJ allowed the recognition of the first XB that involves a nickel(II) center. Moreover, we analyzed the geometrical parameters of the analogous palladium(II)-containing MOF AMIJIR from the same report49 [d(I1···Pd1) = 3.4978(3) Å vs RvdW(Pd) + RvdW(I) = 3.61 Å;27 ∠(C−I···Ni) = 177.57(7)°) and concluded that d8-palladium(II) systems might also behave as nucleophilic XB accepting centers. 2.3.2. Theoretical Verification of the Halogen Bonding in AMIJAJ. We confirmed theoretically the formation of both interactions, I···Ni halogen and Ni···N semicoordination bonds (Table 8, Figures 13 and 14), and the estimated strengths for these contacts are 1.6 (I···Ni) and 5.7−7.5 (Ni···N) kcal/mol. 2.4. Electrophilic−Nucleophilic Dualism of Nickel(II) Centers: A Boundary Case. 2.4.1. Crystal and Molecular Structures of 1·2FIB at 100 K. The crystal structure of 1·2FIB (Figure 15) is composed of 2D-layers of the complex that alternate with 2D-layers of FIB. In these layers, FIBs are connected to each other via the C−I···I XB contacts (Table 1) (the I2S···I1S distance is 3.8234(6) Å, the ∠(C3S−I2S···I1S) angle is 171.88(12)°, and the ∠(I2S···I1S−C1S) angle is 111.50(14)°) (Table S2) and also by π-stacking (the distance between two parallel arene planes is 3.423(3) Å; the distance of 3.5 Å is usually used for identification of π-stacking55), and lp···π interaction (the distance C6S···I2S between two adjacent arenes is 3.598(5) Å, less than RvdW(C) + RvdW(I) = 3.68 Å; Figure 16, Table 3). The complexes are linked through the C3−H3C···N2 contacts between the H atoms of the methyl groups and the N2 atom of the nitrosoguanidinate ligand. Several types of noncovalent interactions between 1 and FIB were identified (Figure 17). Each complex 1 is surrounded by four C6F3I3, and two of these arenes form short Ni1···I3S contacts with the metal center, and the other two are linked via the bifurcated C1S−I1S···(N2−N1O1) contacts with nitrosoguanidinate ligands. The most intriguing feature of the structure is the presence of the Ni1···I3S−C5S (3.3886(5) Å) contact (Table 2), which is significantly shorter than the sum of Bondi’s vdW radii (RvdW(Ni) + RvdW(I) = 3.61 Å) and exhibits the ∠(Ni1···I3S− C5S) angle of 142.51(14)°. This Ni···I−CAr contact could not be unequivocally attributed either to semicoordination bond Ni···I or to metal−iodine XB. Although FIB has already been used for cocrystallization with other nickel(II) complexes, all so far obtained complexes are octahedral, and logically, no metalinvolved interactions were observed.56 The distances I1S···N2 and I1S···O1 (3.286(4) and 3.003(3) Å, correspondingly) are significantly shorter than the sums of Bondi’s vdW radii (RvdW(I) + RvdW(N) = 3.53 and RvdW(I) + RvdW(O) = 3.50 Å) and ∠(C1S−I1S···N2) and ∠(C1S−I1S··· O1) angles are 148.91(15) and 170.80(15)°, respectively. These parameters favor the existence of the bifurcated XB between the iodine of the arene and the N and O atoms of the nitrosoguanidinate ligand.

the IUPAC definition for XB, we verified structure AMIJAJ, namely, Fe(2-iodopyrazine)(H2O)Ni(CN)4, featuring unusual C−I···Ni contacts (Figure 12); the study that first describes this

Figure 12. Fragment of the structure of AMIJAJ featuring the C−I···Ni XB.

structure49 was devoted exclusively to magnetic properties of Fe(2-iodopyrazine)(H2O)Ni(CN)4 based MOFs, and these contacts were out of scope of that study. In the molecular structure of AMIJAJ, the distance I1···Ni1 is significantly less than the Bondi’s vdW sum (3.4702(17) vs 3.61 Å)27 and the ∠(C−I···Ni) angle (177.8(4)°) is very close to 180°. Consideration of these parameters indicate that the iodine atom turned to the nickel center by its σ-hole. In addition, rather strong Ni1···N2 semicoordination (2.627(12) vs 3.18 Å)27 was detected upon our processing of the available27 crystallographic data. It is believed that AMIJAJ features a push−pull system, where the N2 atom exhibits a push effect on the nickel(II) dz2 orbital of the [Ni(CN)4]2− plane, whereas the iodine center provides a symbiotic pull effect on this orbital (Figure 13).

Figure 13. Push−pull effect in AMIJAJ (right) in comparison with the nickel(II) center having the symmetrical environment (left). J


Article

Inorganic Chemistry

Table 8. Values of the Density of All Electrons [ρ(r)], Laplacian of Electron Density [∇2ρ(r)], Energy Density [Hb], Potential Energy Density [V(r)], and Lagrangian Kinetic Energy [G(r)] (Hartree) at the Bond Critical Points (3, −1), Corresponding to I···Ni and Ni···N Noncovalent Interactions in AMIJAJ, and bond length [l (Å)] as well as Energies for This Contact [Eint (kcal/ mol)], Defined by Two Approaches

a

model structure

ρ(r)

∇2ρ(r)

Hb

V(r)

G(r)

Einta

Eintb

l

AMIJAJ (I···Ni) AMIJAJ (Ni···N)

0.010 0.024

0.027 0.074

0.001 −0.003

−0.005 −0.024

0.006 0.021

1.6 7.5

1.6 5.7

3.470 2.627

Eint = −V(r)/2.28 bEint = 0.429G(r).29

Figure 14. Contour line diagram of the Laplacian distribution ∇2ρ(r), bond paths, and selected zero-flux surfaces (left) and RDG isosurface (right) referring to I···Ni and Ni···N noncovalent interactions in AMIJAJ. Bond critical points (3, −1) are shown in blue, nuclear critical points (3, −3) in pale brown, and ring critical points (3, +1) in orange. Length units in Å, RDG isosurface values are given in hartree.

Figure 15. Views along a axis of 1·2FIB (100).

K


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Inorganic Chemistry

1·2I2). It is in line with the difference in the ∠(Ni···I−X) valence angles observed at 100 K (X = I2S and C5S for 1·2I2 and 1·2FIB, respectively; Tables S4−S7) and serves as an additional indication of the different nature of the Ni···I interactions in the studied associates. In 1·2I2 and 1·2FIB, the inverse relation between the intermolecular distance and its thermally induced change was also observed upon the comparison of the temperature dependences of the bifurcated C−I···(N−NO) XBs. Although the I1S···N2 distance changes only slightly in crystals of both associates (less than 0.02 Å within the studied temperature range), the lengthening of the I1S···O1 separation upon heating is two-times larger in 1· 2I2 (0.10 Å vs 0.05 Å in 1·2FIB), whereas in 1·2I2, the I1S···O1 contact is always shorter than that in 1·2FIB. Since there is no evidence of any pronounced change of interaction angles from the VTXRD data (the maximal change is less than 4°; Tables S5 and S7), without theoretical computations it is difficult to assume the presence of thermally induced transformations of these Ni-involving interactions, for which the geometry data cannot be attributed unambiguously (the interaction angle of about 140° for ∠(Ni1···I3S−C5S) in 1·2FIB and ∠(I2S−I1S··· N2) in both structures). The thermally induced changes of contacts within the layers of FIB molecules in 1·2FIB were found to be close to each other, and upon heating from 100 to 300 K the I···I distance of the C−I···I XB lengthens 0.07 Å, the interplane distance corresponding to π-stacking increases 0.08 Å, and the C6S···I2S contact corresponding to the lp(I)···π interaction increases 0.05 Å. Similar compliance of all these interactions agrees well with the layered-type crystal structure of 1·2FIB. Notably, the total thermally induced change, calculated as sum of changes observed for all established shortened contacts (including the I1S···C1 one in 1·2I2) within the 100−300 K temperature range, is nearly the same in crystals of both

Figure 16. Short contacts between FIBs in 1·2FIB. Molecules of 1 were omitted for simplicity.

Figure 17. Surroundings of complex 1 in 1·2FIB.

2.4.2. Variable Temperature XRD Studies of 1·2FIB and Comparison of VTXRD Data for 1·2I2 and 1·2FIB. The comparison of the temperature dependence of the Ni···I distance in crystals of the two associates revealed that the Ni···I contact in 1·2FIB, which is always shorter than that in 1·2I2, changes more significantly upon heating (by 0.08 Å vs 0.06 Å in

Figure 18. Contour line diagrams of the Laplacian distribution ∇2ρ(r), bond paths, and selected zero-flux surfaces (left) and RDG isosurfaces (right) referring to different noncovalent interactions in 1·2FIB. Bond critical points (3, −1) are shown in blue, nuclear critical points (3, −3) in pale brown, ring critical points (3, +1) in orange, and cage critical points (3, +3) in light green. Length units in Å, RDG isosurface values are given in hartree. L


Article

Inorganic Chemistry Table 9. Results of the Hirshfeld Surface Analysis for X-ray Structures of 1·2I2 and 1·2FIB Obtained at 100 K

a

X-ray structure

contributions of different intermolecular contacts to the molecular Hirshfeld surfacea

1·2I2 1·2FIB

I−H 26.2%, H−H 23.7%, O−H 16.1%, N−H 15.4%, I−N 7.3%, I−O 4.8%, I−C 2.8%, I−Ni 2.6% F−H 26.2%, H−H 15.9%, N−H 15.7%, I−H 10.8%, I−O 7.1%, I−N 6.4%, C−H 4.9%, O−H 4.7%, O−C 3.1%, I−Ni 2.6%, F−N 1.4%

The contributions of all other intermolecular contacts do not exceed 1%.

surfaces of 1·2I2 and 1·2FIB. In these Hirshfeld surfaces, the regions of shortest intermolecular contacts are visualized by red circle areas. The main partial contributions of different intermolecular contacts to the molecular Hirshfeld surfaces are I−H 26.2%, H−H 23.7%, O−H 16.1%, N−H 15.4%, and I−N 7.3% in case of 1·2I2 and F−H 26.2%, H−H 15.9%, N−H 15.7%, I−H 10.8%, I−O 7.1%, and I−N 6.4% in case of 1·2FIB. Thus, the Hirshfeld surface analysis for the obtained X-ray structures of 1·2I2 and 1·2FIB at 100 K reveals that in both cases crystal packing is determined primarily by intermolecular contacts with the hydrogen and iodine atoms.

associates (0.35 and 0.34 Å for 1·2I2 and 1·2FIB, respectively). Moreover, the relative increase in volume of the independent part of the unit cell is about 3% for both structures. It indicates similar temperature dependences of crystal lattice energies for both structures and is in concordance with close density values calculated from the XRD data (at 100 K densities are 2.792 and 2.831 g·cm−3 for 1·2I2 and 1·2FIB, respectively) (Tables S4− S7). 2.4.3. Theoretical Study Supporting Identification of the Boundary Noncovalent Interactions in 1·2FIB. For the X-ray structure of 1·2FIB at 100 K, we conducted the same computational study as described in section 2.2.3 of the nature and energies of different existing noncovalent interactions. Results are summarized in Tables 4 and 5, the contour line diagrams of the Laplacian distribution ∇2ρ(r), bond paths, selected zero-flux surfaces, and RDG isosurfaces are shown in Figure 18. The QTAIM analysis also demonstrates the presence of appropriate bond critical points (BCPs) (3, −1) for all listed in Table 4 noncovalent interactions in 1·2FIB. The low magnitude of the electron density (0.007−0.016 hartree), positive values of the Laplacian (0.025−0.055 hartree), and close to zero (0.000− 0.001 hartree) energy density in these BCPs are typical for noncovalent interactions and comparable to these parameters for 1·2I2. The estimated energies for these contacts are 1.3−3.5 kcal/mol. The ratio −G(r)/V(r) > 1 for all contacts; thus their nature is purely noncovalent. The analysis of the results of DFT calculations and topological analysis of the electron density distribution within the framework of Bader’s theory (QTAIM method) for the X-ray structures of 1·2FIB at the different temperatures also reveals that thermal expansion has a little effect on the electron density properties and strengths of the Ni···I contacts; appropriate estimated noncovalent interaction energies range from 2.5 to 1.9 kcal/mol. 2.4.4. Hirshfeld Surface Analysis for the X-ray Structures of 1·2I2 and 1·2FIB. The molecular Hirshfeld surface represents an area where molecules come into contact, and its analysis gives the possibility of additional insight into the nature of intermolecular interactions in the crystal state. We carried out the Hirshfeld surface analysis for X-ray structures of 1·2I2 and 1·2FIB obtained at 100 K (Table 9) to understand what kind of intermolecular contact gives the largest contributions in crystal packing. For the visualization, we have used a mapping of the normalized contact distance (dnorm); its negative value enables identification of molecular regions of substantial importance for detection of short contacts. Figure 19 depicts the Hirshfeld

3. CONCLUSIONS The results of this work can be considered from the following perspectives. First, we observed that the electron belt of molecular iodine forms noncovalent contacts with the nickel(II) center to give a NiII···I−I semicoordination bond (97% from the sum of Bondi’s vdW radii for Ni and I; estimated strength is 2.2 kcal/mol at the M06/DZP-DKH level of theory within the framework of QTAIM approach). Although I2 quite rarely behaves as a ligand, binding through its electron belt to AgI,57 PbII,58 and RhII59 centers and the relevant ability to serve as a hydrogen60 and halogen61 bond acceptor have been reported, and our observation is the first example of electron belt semicoordination of I2 to a nickel(II) center. The finding of Ni···I−I semicoordination stimulated our interest in this type of weak interactions and our processing of the available XRD (CCDC) data accompanied with the theoretical analysis of four representative structures allowed verification of some additional examples of Ni···I semicoordination (Table 6) with very little or no contribution of a covalent component. The vast majority of these cases, as expected, include weak binding (or, in other words, semicoordination) of anionic ligands to the positive area of nickel centers in cationic complexes, whereas the linkage including neutral iodine species or neutral nickel complexes is still uncommon. Moreover, semicoordination of other nucleophilic centers, namely, the reported Ni···Cl34 and the Ni···N semicoordination detected in this work (section 2.3.1), led us to the conclusion that semicoordination is not an unusual, albeit predominantly overlooked, phenomenon in the coordination chemistry, and already available CCDC data should be again considered under this angle. In a broader sense, one more issue relevant to semicoordination needs further attention. Despite some examples of “semicoordination bond” being reported, especially those for copper(II) centers,18 this phenomenon is incomparably less common than that of the “coordination bond”. Although initial reports on semicoordination appeared in the 1960s,17a clear definition of this bonding has not yet been formulated, and only various epithets such as “weak interactions”, “negligible binding”, “loosely bound centers”, etc. were applied to describe this kind of linkage. The “coordination bond” is usually considered as a 2-center/2-electron covalent bond, in which two electrons derive from the same atom. It seems that the “semicoordination bond” can be treated as a 2-center/2-

Figure 19. Hirshfeld surfaces of 1·2I2 and 1·2FIB. M


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Inorganic Chemistry electron (from one atom) noncovalent linkage. Accordingly, M···X is real semicoordination, when the interatomic distance between M and an appropriate nucleophilic atom of X is less than the sum of their vdW radii but significantly larger than an average value of the corresponding M−X coordination bond. The noncovalent character of the M···X linkage should be determined based upon the developed theoretical approaches. To summarize this part of the article, a semicoordination bond (SCB) occurs when there is evidence of a net attractive noncovalent interaction between an electrophilic region associated with metal center in a molecular entity and a nucleophilic region associated with a nonmetal atom in another or in the same molecular entity. In a typical M···X semicoordination, (i) the M···X distance is smaller than van der Waals radii sum, (ii) the angles around M···X contact relative to other ligands tend to 90°, and (iii) the forces involved in the formation of the semicoordination bond are primarily electrostatic, but polarization, charge transfer, and dispersion contributions all play an important role. The relative roles of the different forces may vary from one case to the other; (iv) the analysis of the electron density topology usually shows a bond path (“bond path” and “bond critical point” are defined as the following: “Within the topological electron distribution theory, the line resulting from the addition of two gradient paths of the electron density function emanating from the bond critical point located between each of two neighboring atomic basins” and “Within the topological electron distribution theory, a (3, −1) critical point (the point of the gradient field of the electron density within a given neutral configuration in which ∇ρ(r,q) = 0) which is a local maximum in two directions and is a local minimum in the third, that is, a saddle point in the three directions”) connecting M and X and a bond critical point between M and X. Second, upon the inspection of various Ni···I noncovalent binding modes, we found that the nickel(II) center in AMIJAJ49 is linked via its dz2 orbital to the σ-hole of the iodine center of 2iodopyrazine. We also identified the same type of halogen bonding in the palladium(II) congener (structure AMIJIR49). All these data, along with our previous observation of halogen bonding between a platinum(II) center and halomethanes,16a indicate that all metal(II) centers of the platinum triad could exhibit a nucleophilic character providing their dz2 orbitals for halogen bonding. It is of note that the cooperative semicoordination−XB effects (found in both AMIJAJ and AMIJIR) between push effect of the N semicoordination and pull effect of iodine XB (Figure 13) deserve further investigation. Third, as can be inferred from consideration of all our results, nickel(II) centers, depending on ligand environment and the nature of the iodine donor, might exhibit electrophilic− nucleophilic dualism (Figure 20) and either form semicoordination bond demonstrating the electrophilic character or behave as a halogen bond acceptor via its dz2 orbital thus displaying nucleophilic nature. Some boundary cases are also possible; namely, in 1·2FIB, the NiII···I−CAr noncovalent interactions (94% from the sum of Bondi’s vdW radii for Ni and I; estimated strength is 2.2−2.5 kcal/mol) may be either semicoordination or metal-involving halogen bonding. To the best of our knowledge, this work is the first emphasizing electrophilic−nucleophilic dualism of any metal center toward noncovalent interactions. We believe that some other metal centers could also exhibit the same behavior. Indeed, previously we reported on XB between a nucleophilic PtII center and halomethanes.16a On the other hand, an example

Figure 20. Schematic representation of electrophilic−nucleophilic dualism of NiII centers.

of PtII···I semicoordination62 (in the original paper, this linkage was treated as a conventional coordination) indicates that platinum(II) centers may exhibit electrophilic nature thus favoring semicoordination.

4. EXPERIMENTAL SECTION 4.1. Syntheses of 1, 1·2I2, and 1·2FIB. Complex 1 was synthesized following the previously published procedure.20 For preparation of associates 1·2I2 and 1·2FIB, complex 1 (10 mg, 0.035 mmol) was added to a solution of I2 (17.6 mg, 0.07 mmol) or FIB (27.8 mg, 0.07 mmol), correspondingly, in CHCl3 (10 mL), placed in a 20 mL round-bottomed flask. Each the reaction mixture was stirred in an ultrasonic bath at RT and then left for slow evaporation at RT. Dark red crystals of 1·2I2 and 1·2FIB were formed after 7−9 d. 4.2. X-ray Diffraction and VTXRD Studies. VTXRD experiments were performed for suitable crystals of 1·2I2 and 1·2FIB using the Bruker APEX II Duo diffractometer (graphite monochromated Mo Kα radiation, λ = 0.71073 Å, ω-scans) and the Oxford Cobra lowtemperature device. After heating crystals from 100 to 300 K, two additional experiments were performed for each associate at lower temperature (100 K) to check the reversible character of all changes established upon heating. For these two experiments, the geometry data was found to be nearly the same with the preheating data obtained at 100 K; the mean-square difference was less than 0.0002 Å2. Before the variable temperature series, the low-temperature device was adjusted (the position of its jet nozzle and the level of gas flow) using 2-methyl-2-nitropropane crystals. To avoid problems of comparison of several data sets collected at different crystal position, for each studied associate, the single crystal was one-time mounted on the sample holder using two-pack glue before the experiment. Absorption effects for the X-ray diffraction data on the 1·2I2 and 1·2FIB crystals are accounted for by empirical corrections based on measurements of equivalent reflections. The structures of 1·2I2 and 1·2FIB were solved by direct methods and refined by the full-matrix least-squares against F2 in anisotropic approximation for non-hydrogen atoms. The positions of hydrogen atoms were localized from the difference Fourier synthesis of residual electron density; the hydrogen atoms were refined in riding model in isotropic approximation. Crystallography data and refinement details are listed in Tables S1 and S2 (Supporting Information). All calculations were performed using Bruker APEX3,63 ShelXS,64 and ShelXL65 software packages. CCDC 1556681−1556685 and 1556686−1556690 contain all additional information on structures. 4.3. Computational Details. The single point calculations based on the experimental X-ray geometries (crystallographic coordinates; the position of H atoms were not optimized) have been carried out at the DFT level of theory using the M06 functional66 (this functional was specifically developed to describe weak dispersion forces and noncovalent interactions) with the help of Gaussian 0967 program package. The Douglas−Kroll−Hess second order scalar relativistic calculations for requested relativistic core Hamiltonian were carried out using DZP-DKH basis sets68 for all atoms. The topological analysis of the electron density distribution with the help of the atoms in molecules (QTAIM) method developed by Bader30 has been performed by using the Multiwfn program (version 3.3.8).69 The N


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Inorganic Chemistry

Cryst. Growth Des. 2014, 14 (6), 2697−2702. (c) Mahmudov, K. T.; Kopylovich, M. N.; Guedes da Silva, M. F. C.; Pombeiro, A. J. L. Coord. Chem. Rev. 2017, 345, 54−72. (2) (a) Cavallo, G.; Metrangolo, P.; Milani, R.; Pilati, T.; Priimagi, A.; Resnati, G.; Terraneo, G. Chem. Rev. 2016, 116 (4), 2478−2601. (b) Cavallo, G.; Metrangolo, P.; Pilati, T.; Resnati, G.; Sansotera, M.; Terraneo, G. Chem. Soc. Rev. 2010, 39 (10), 3772−3783. (c) Gilday, L. C.; Robinson, S. W.; Barendt, T. A.; Langton, M. J.; Mullaney, B. R.; Beer, P. D. Chem. Rev. 2015, 115 (15), 7118−7195. (3) Wang, W. Z.; Ji, B. M.; Zhang, Y. J. Phys. Chem. A 2009, 113 (28), 8132−8135. (4) Bauzá, A.; Mooibroek, T. J.; Frontera, A. Angew. Chem., Int. Ed. 2013, 52 (47), 12317−12321. (5) (a) Mahmoudi, G.; Bauza, A.; Amini, M.; Molins, E.; Mague, J. T.; Frontera, A. Dalton Trans. 2016, 45 (26), 10708−10716. (b) Mahmoudi, G.; Bauza, A.; Frontera, A.; Garczarek, P.; Stilinovic, V.; Kirillov, A. M.; Kennedy, A.; Ruiz-Perez, C. CrystEngComm 2016, 18 (28), 5375−5385. (c) Mahmoudi, G.; Bauza, A.; Frontera, A. Dalton Trans. 2016, 45 (12), 4965−4969. (d) Servati Gargari, M.; Stilinović, V.; Bauzá, A.; Frontera, A.; McArdle, P.; Van Derveer, D.; Ng, S. W.; Mahmoudi, G. Chem. - Eur. J. 2015, 21 (49), 17951−17958. (6) Hunter, C. A.; Lawson, K. R.; Perkins, J.; Urch, C. J. J. Chem. Soc., Perkin Trans. 2 2001, 2 (5), 651−669. (7) Wang, H.; Wang, W. Z.; Jin, W. J. Chem. Rev. 2016, 116 (9), 5072−5104. (8) Chernyshev, A. N.; Chernysheva, M. V.; Hirva, P.; Kukushkin, V. Y.; Haukka, M. Dalton Trans. 2015, 44 (32), 14523−14531. (9) Bolotin, D. S.; Burianova, V. K.; Novikov, A. S.; Demakova, M. Y.; Pretorius, C.; Mokolokolo, P. P.; Roodt, A.; Bokach, N. A.; Suslonov, V. V.; Zhdanov, A. P.; Zhizhin, K. Y.; Kuznetsov, N. T.; Kukushkin, V. Y. Organometallics 2016, 35 (20), 3612−3623. (10) (a) Huynh, H. V.; Wong, L. R.; Ng, P. S. Organometallics 2008, 27 (10), 2231−2237. (b) de Oliveira, A. B.; Beck, J.; Mellone, S. E. B. S.; Daniels, J. Acta Cryst. Sect. E 2017, 73 (6), 859−863. (c) Yadav, M. K.; Rajput, G.; Prasad, L. B.; Drew, M. G. B.; Singh, N. New J. Chem. 2015, 39 (7), 5493−5499. (11) Mikhaylov, V. N.; Sorokoumov, V. N.; Korvinson, K. A.; Novikov, A. S.; Balova, I. A. Organometallics 2016, 35 (11), 1684− 1697. (12) Tiekink, E. R. T. Coord. Chem. Rev. 2017, 345, 209−228. (13) Erbas-Cakmak, S.; Leigh, D. A.; McTernan, C. T.; Nussbaumer, A. L. Chem. Rev. 2015, 115 (18), 10081−10206. (14) Campbell, M. G.; Powers, D. C.; Raynaud, J.; Graham, M. J.; Xie, P.; Lee, E.; Ritter, T. Nat. Chem. 2011, 3 (12), 949−953. (15) Cao, H.-J.; Zhao, Q.; Zhang, Q.-F.; Li, J.; Hamilton, E. J. M.; Zhang, J.; Wang, L.-S.; Chen, X. Dalton Trans. 2016, 45 (25), 10194− 10199. (16) (a) Ivanov, D. M.; Novikov, A. S.; Ananyev, I. V.; Kirina, Y. V.; Kukushkin, V. Y. Chem. Commun. 2016, 52 (32), 5565−5568. (b) Kolari, K.; Sahamies, J.; Kalenius, E.; Novikov, A. S.; Kukushkin, V. Y.; Haukka, M. Solid State Sci. 2016, 60, 92−98. (17) (a) Brown, D. S.; Lee, J. D.; Melsom, B. G. A.; Hathaway, B. J.; Procter, I. M.; Tomlinson, A. A. G. Chem. Commun. 1967, 369−371. (b) Valach, F. Polyhedron 1999, 18 (5), 699−706. (18) (a) Awwadi, F.; Willett, R. D.; Twamley, B. Cryst. Growth Des. 2011, 11 (12), 5316−5323. (b) Drahos, B.; Herchel, R.; Travnicek, Z. Inorg. Chem. 2015, 54 (7), 3352−3369. (c) Massoud, S. S.; Louka, F. R.; Xu, W.; Perkins, R. S.; Vicente, R.; Albering, J. H.; Mautner, F. A. Eur. J. Inorg. Chem. 2011, 2011 (23), 3469−3479. (19) (a) Yandanova, E. S.; Ivanov, D. M.; Kuznetsov, M. L.; Starikov, A. G.; Starova, G. L.; Kukushkin, V. Y. Cryst. Growth Des. 2016, 16 (5), 2979−2987. (b) Ivanov, D. M.; Novikov, A. S.; Starova, G. L.; Haukka, M.; Kukushkin, V. Y. CrystEngComm 2016, 18 (28), 5278−5286. (c) Mikherdov, A. S.; Kinzhalov, M. A.; Novikov, A. S.; Boyarskiy, V. P.; Boyarskaya, I. A.; Dar’in, D. V.; Starova, G. L.; Kukushkin, V. Y. J. Am. Chem. Soc. 2016, 138 (42), 14129−14137. (d) Serebryanskaya, T. V.; Novikov, A. S.; Gushchin, P. V.; Haukka, M.; Asfin, R. E.; Tolstoy, P. M.; Kukushkin, V. Y. Phys. Chem. Chem. Phys. 2016, 18 (20), 14104−14112. (e) Anisimova, T. B.; Kinzhalov, M. A.; Guedes da

Cartesian atomic coordinates of model supramolecular clusters are presented in Table S9. The Hirshfeld molecular surfaces were generated by CrystalExplorer 3.1 program70 based on the results of the X-ray study. The normalized contact distances, dnorm,71 based on Bondi’s van der Waals radii,27 were mapped into the Hirshfeld surface. In the color scale, negative values of dnorm are visualized by the red color indicating contacts shorter than the sum of van der Waals radii. The white color denotes intermolecular distances close to van der Waals contacts with dnorm equal to zero. In turn, contacts longer than the sum of van der Waals radii with positive dnorm values are colored with blue.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b02224. Crystallographic data and refinement details for 1·2I2 and 1·2FIB, select bond lengths and angles for 1, 1·2I2, and 1· 2FIB, variation of distances, unit cell volumes and interaction angles from VTXRD for 1·2I2 and 1·2FIB, parameters of HBs in 1·2I2 and 1·2FIB under 100 K, and Cartesian coordinates of model clusters (PDF) Video of temperature variation effects on 1·2FIB I···Ni interaction (MP4) Video of temperature variation effects on 1·2I2 lp−π interaction (MP4) Video of temperature variation effects on 1·2I2 Ni···I interaction (MP4) Accession Codes

CCDC 1556681−1556690 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

ORCID

Zarina M. Bikbaeva: 0000-0001-5495-5695 Daniil M. Ivanov: 0000-0002-0855-2251 Alexander S. Novikov: 0000-0001-9913-5324 Ivan V. Ananyev: 0000-0001-6867-7534 Nadezhda A. Bokach: 0000-0001-8692-9627 Vadim Yu. Kukushkin: 0000-0002-2253-085X Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS Synthetic part of this work was supported by the Russian Science Foundation (14-13-00060-P). A.S.N. and I.V.A. thank the Russian Foundation for Basic Research for support of the theoretical (project 16-33-60063) and VTXRD (project 16-3360133) studies, correspondingly. A.S.N. is thankful to Saint Petersburg State University and Santander Bank for the opportunity to conduct a part of this work upon two months sabbatical on leave at Instituto Superior Técnico, Universidade de Lisboa (Lisbon, Portugal).

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REFERENCES

(1) (a) Steiner, T. Angew. Chem., Int. Ed. 2002, 41 (1), 48−76. (b) Cavallo, G.; Metrangolo, P.; Pilati, T.; Resnati, G.; Terraneo, G. O


Article

Inorganic Chemistry Silva, M. F. C.; Novikov, A. S.; Kukushkin, V. Y.; Pombeiro, A. J. L.; Luzyanin, K. V. New J. Chem. 2017, 41 (9), 3246−3250. (f) Ivanov, D. M.; Kinzhalov, M. A.; Novikov, A. S.; Ananyev, I. V.; Romanova, A. A.; Boyarskiy, V. P.; Haukka, M.; Kukushkin, V. Y. Cryst. Growth Des. 2017, 17 (3), 1353−1362. (20) Bikbaeva, Z. M.; Novikov, A. S.; Suslonov, V. V.; Bokach, N. A.; Kukushkin, V. Y. Dalton Trans. 2017, 46 (46), 10090−10101. (21) Bauzá, A.; Mooibroek, T. J.; Frontera, A. ChemPhysChem 2015, 16 (12), 2496−2517. (22) Clark, T.; Hennemann, M.; Murray, J. S.; Politzer, P. J. Mol. Model. 2007, 13 (2), 291−296. (23) Desiraju, G. R.; Ho, P. S.; Kloo, L.; Legon, A. C.; Marquardt, R.; Metrangolo, P.; Politzer, P.; Resnati, G.; Rissanen, K. Definition of the halogen bond (IUPAC Recommendations 2013). Pure Appl. Chem. 2013, 85, 1711. (24) Bertolotti, F.; Shishkina, A. V.; Forni, A.; Gervasio, G.; Stash, A. I.; Tsirelson, V. G. Cryst. Growth Des. 2014, 14 (7), 3587−3595. (25) (a) Bennion, J. C.; Vogt, L.; Tuckerman, M. E.; Matzger, A. J. Cryst. Growth Des. 2016, 16 (8), 4688−4693. (b) Goud, N. R.; Bolton, O.; Burgess, E. C.; Matzger, A. J. Cryst. Growth Des. 2016, 16 (3), 1765−1771. (c) Li, X.; Parkin, S.; Lehmler, H.-J. Acta Crystallogr., Sect. E: Struct. Rep. Online 2014, 70 (5), o607. (d) Tothadi, S.; Sanphui, P.; Desiraju, G. R. Cryst. Growth Des. 2014, 14 (10), 5293−5302. (e) Wardell, J. L.; Tiekink, E. R. T. Acta Crystallogr., Sect. E: Struct. Rep. Online 2012, 68 (3), o761. (26) (a) Ji, B. M.; Wang, W. Z.; Deng, D. S.; Zhang, Y. Cryst. Growth Des. 2011, 11 (8), 3622−3628. (b) Syssa-Magale, J. L.; Boubekeur, K.; Palvadeau, P.; Meerschaut, A.; Schollhorn, B. CrystEngComm 2005, 7, 302−308. (c) Ji, B. M.; Wang, W. Z.; Deng, D. S.; Zhang, Y.; Cao, L.; Zhou, L.; Ruan, C. S.; Li, T. S. CrystEngComm 2013, 15 (4), 769−774. (27) Bondi, A. J. Phys. Chem. 1966, 70 (9), 3006−3007. (28) Espinosa, E.; Molins, E.; Lecomte, C. Chem. Phys. Lett. 1998, 285 (3), 170−173. (29) Vener, M. V.; Egorova, A. N.; Churakov, A. V.; Tsirelson, V. G. J. Comput. Chem. 2012, 33 (29), 2303−2309. (30) Bader, R. F. W. Chem. Rev. 1991, 91 (5), 893−928. (31) (a) Ivanov, D. M.; Kirina, Y. V.; Novikov, A. S.; Starova, G. L.; Kukushkin, V. Y. J. Mol. Struct. 2016, 1104, 19−23. (b) Kulish, K. I.; Novikov, A. S.; Tolstoy, P. M.; Bolotin, D. S.; Bokach, N. A.; Zolotarev, A. A.; Kukushkin, V. Y. J. Mol. Struct. 2016, 1111, 142−150. (c) Ding, X.; Tuikka, M. J.; Hirva, P.; Kukushkin, V. Y.; Novikov, A. S.; Haukka, M. CrystEngComm 2016, 18 (11), 1987−1995. (d) Novikov, A. S.; Kuznetsov, M. L.; Pombeiro, A. J. L. Chem. - Eur. J. 2013, 19 (8), 2874−2888. (32) Johnson, E. R.; Keinan, S.; Mori-Sánchez, P.; Contreras-García, J.; Cohen, A. J.; Yang, W. J. Am. Chem. Soc. 2010, 132 (18), 6498− 6506. (33) Espinosa, E.; Alkorta, I.; Elguero, J.; Molins, E. J. Chem. Phys. 2002, 117 (12), 5529−5542. (34) Gerdes, A.; Bond, M. R. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 2009, 65 (10), m398−m400. (35) Koner, R.; Lin, H.-H.; Wei, H.-H.; Mohanta, S. Inorg. Chem. 2005, 44 (10), 3524−3536. (36) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D. G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, 12, S1−S83. (37) Goodman, D. C.; Buonomo, R. M.; Farmer, P. J.; Reibenspies, J. H.; Darensbourg, M. Y. Inorg. Chem. 1996, 35 (13), 4029−4037. (38) Mills, D. K.; Reibenspies, J. H.; Darensbourg, M. Y. Inorg. Chem. 1990, 29 (22), 4364−4366. (39) Prasad, L.; McAuley, A. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1983, 39 (9), 1175−1177. (40) Adam, K. R.; Antolovich, M.; Brigden, L. G.; Leong, A. J.; Lindoy, L. F.; Baillie, P. J.; Uppal, D. K.; McPartlin, M.; Shah, B.; Proserpio, D.; Fabbrizzi, L.; Tasker, P. A. J. Chem. Soc., Dalton Trans. 1991, 10, 2493−2501. (41) Ruiz, R.; Julve, M.; Cano, J.; Soto, J.; Martínez-Máñez, R.; Muñoz, C.; Payá, J. Transition Met. Chem. 1993, 18 (5), 523−527. (42) McAuley, A.; Subramanian, S. Inorg. Chem. 1991, 30 (3), 371− 378.

(43) Nanda, K. K.; Das, R.; Venkatsubramanian, K.; Paul, P.; Nag, K. J. Chem. Soc., Dalton Trans. 1993, 16, 2515−2520. (44) Mochizuki, K.; Kashima, K.; Weyhermüller, T. Inorg. Chem. Commun. 2006, 9 (9), 891−894. (45) Cunningham, D.; McArdle, P.; Mitchell, M.; Ní Chonchubhair, N.; O’Gara, M.; Franceschi, F.; Floriani, C. Inorg. Chem. 2000, 39 (8), 1639−1649. (46) Gray, L. R.; Higgins, S. J.; Levason, W.; Webster, M. J. Chem. Soc., Dalton Trans. 1984, 7, 1433−1439. (47) Stomberg, R. Acta Chem. Scand. 1969, 23, 3498. (48) Daneshvar, N.; Saghatforoush, L. A.; Khandar, A. A.; Entezami, A. A. Acta Chim. Sloven. 2003, 50, 207−222. (49) Kucheriv, O. I.; Shylin, S. I.; Ksenofontov, V.; Dechert, S.; Haukka, M.; Fritsky, I. O.; Gural’skiy, I. A. Inorg. Chem. 2016, 55 (10), 4906−4914. (50) Meyer, F.; Kozlowski, H. 6.3-Nickel. Comprehensive Coordination Chemistry II; Pergamon: Oxford, 2003; pp 247−554. (51) Desiraju, G. R.; Ho, P. S.; Kloo, L.; Legon, A. C.; Marquardt, R.; Metrangolo, P.; Politzer, P.; Resnati, G.; Rissanen, K. Pure Appl. Chem. 2013, 85 (8), 1711−1713. (52) Rissanen, K. CrystEngComm 2008, 10 (9), 1107−1113. (53) Gossage, R. A.; Ryabov, A. D.; Spek, A. L.; Stufkens, D. J.; van Beek, J. A. M.; van Eldik, R.; van Koten, G. J. Am. Chem. Soc. 1999, 121 (11), 2488−2497. (54) Shaffer, D. W.; Ryken, S. A.; Zarkesh, R. A.; Heyduk, A. F. Inorg. Chem. 2012, 51 (22), 12122−12131. (55) Główka, M. L.; Martynowski, D.; Kozłowska, K. J. Mol. Struct. 1999, 474 (1), 81−89. (56) Pfrunder, M. C.; Micallef, A. S.; Rintoul, L.; Arnold, D. P.; McMurtrie, J. Cryst. Growth Des. 2016, 16 (2), 681−695. (57) (a) Cameron, T. S.; Passmore, J.; Wang, X. Angew. Chem., Int. Ed. 2004, 43 (15), 1995−1998. (b) Malinowski, P. J.; Himmel, D.; Krossing, I. Angew. Chem., Int. Ed. 2016, 55 (32), 9262−9266. (c) Malinowski, P. J.; Himmel, D.; Krossing, I. Angew. Chem., Int. Ed. 2016, 55 (32), 9259−9261. (58) Wang, G.-E.; Xu, G.; Liu, B.-W.; Wang, M.-S.; Yao, M.-S.; Guo, G.-C. Angew. Chem., Int. Ed. 2016, 55 (2), 514−518. (59) Cotton, F. A.; Dikarev, E. V.; Petrukhina, M. A. Angew. Chem., Int. Ed. 2000, 39 (13), 2362−2364. (60) (a) Tuikka, M.; Niskanen, M.; Hirva, P.; Rissanen, K.; Valkonen, A.; Haukka, M. Chem. Commun. 2011, 47 (12), 3427−3429. (b) Haukka, M.; Hirva, P.; Rissanen, K., Dihalogens as Halogen Bond Donors. Non-covalent Interactions in the Synthesis and Design of New Compounds; John Wiley & Sons, Inc: 2016; pp 185−197. (61) Bertolotti, F.; Shishkina, A. V.; Forni, A.; Gervasio, G.; Stash, A. I.; Tsirelson, V. G. Cryst. Growth Des. 2014, 14 (7), 3587−3595. (62) Stephenson, N. C. J. Inorg. Nucl. Chem. 1962, 24, 791−795. (63) APEX3; Bruker ASX Inc.: Wisconsin, USA, 2012. (64) Sheldrick, G. Acta Crystallogr., Sect. A: Found. Crystallogr. 2008, 64 (1), 112−122. (65) Sheldrick, G. Acta Crystallogr., Sect. A: Found. Adv. 2015, 71 (1), 3−8. (66) Zhao, Y.; Truhlar, D. G. Theor. Chem. Acc. 2008, 120 (1), 215− 241. (67) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.; P


Article

Inorganic Chemistry Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, revision C.01; Gaussian, Inc.: Wallingford, CT, 2009. (68) (a) Barros, C. L.; de Oliveira, P. J. P.; Jorge, F. E.; Canal Neto, A.; Campos, M. Mol. Phys. 2010, 108 (15), 1965−1972. (b) Canal Neto, A.; Jorge, F. E. Chem. Phys. Lett. 2013, 582, 158−162. (c) de Berrêdo, R. C.; Jorge, F. E. J. Mol. Struct.: THEOCHEM 2010, 961 (1), 107−112. (d) Jorge, F. E.; Neto, A. C.; Camiletti, G. G.; Machado, S. F. J. Chem. Phys. 2009, 130 (6), 064108. (69) Lu, T.; Chen, F. J. Comput. Chem. 2012, 33 (5), 580−592. (70) (a) Wolff, S. K.; Grimwood, D. J.; McKinnon, J. J.; Turner, M. J.; Jayatilaka, D.; Spackman, M. A. CrystalExplorer (Version 3.1); University of Western Australia: 2012. (b) Spackman, M. A.; Jayatilaka, D. CrystEngComm 2009, 11 (1), 19−32. (71) McKinnon, J. J.; Jayatilaka, D.; Spackman, M. A. Chem. Commun. 2007, 37, 3814−3816.

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