Synthesis, X-ray Structures and Hirshfeld Analysis of Two Novel Thiocyanate-Bridged Ag(I) Coordination Polymers

: Two novel silver(I) coordination polymers, [Ag( 4BP )(SCN)] n ( 1 ) and {( 4BP H) + [Ag(SCN) 2 ] − } n ( 2 ) ( 4BP = 4-benzoyl pyridine), have been synthesized. The two complexes were prepared using almost the same reagents, which were AgNO 3 , 4BP and NH 4 SCN. The only difference was the presence of 1:1 ( v/v ) HNO 3 in the synthesis of 2 . In the two complexes, the Ag(I) has distorted tetrahedral coordination geometry. The structure of both complexes and the involvement of the thiocyanate anion as a linker between the Ag(I) centers were confirmed using single-crystal X-ray diffraction. 4BP participated as a monodentate ligand in the coordination sphere of complex 1 , while in 2 it is found protonated ( 4BP -H) + and acts as a counter ion, which balances the charge of the anionic [Ag(SCN) 2 ] − moiety. The thiocyanate anion shows different coordination modes in the two complexes. In complex 1 , the thiocyanate anion exhibits a µ 1,1,3 bridging mode, which binds three Ag(I) ions to build a boat-like ten-membered ring structure leading to a two-dimensional coordination polymer. In 2 , there are mixed µ 1,1 and µ 1,3 bridging thiocyanate groups, which form the one-dimensional polymeric chain running in the a -direction. Several interactions affected the stability of the crystal structure of the two complexes. These interactions were examined using Hirshfeld surface analysis. The coordination interactions (Ag-S and Ag-N) have a great impact on the stability of the polymeric structure of the two complexes. Additionally, the hydrogen-bonding interactions are crucial in the assembly of these coordination polymers. The O. . .H (10.7%) and C. . .H (34.2%) contacts in 1 as well as the N ··· H (15.3%) and S ··· H (14.9%) contacts in 2 are the most significant. Moreover, the argentophilic interaction (Ag. . .Ag = 3.378 Å) and π - π stacking play an important role in the assembly of complex 2 .

Pyridine derivatives are among the most often used nitrogen-containing heterocyclic ligands.Due to the variety of ligand design and the ability to form labile and reversible bonds, the metal-pyridine coordination bond is among the most ideal systems for the self-assembly of well-organized CPs [53][54][55][56].Various factors should be taken into consideration for the successful preparation of these polymeric materials, including the reaction conditions [57], the ratio of silver to ligand [58], silver ion stereochemistry coupled with the functionality of the ligands [59] and the characteristics of counter-anions [60].Recently, our research groups reported the synthesis and X-ray structure analysis combined with Hirshfeld and antimicrobial studies of polymeric [Ag(3-cyanopyridine) 2 (CF 3 COO)] n and the dinuclear [Ag(4-benzoylpyridine) 2 ] 2 (CF 3 COO) 2 complexes [61].In addition, the X-ray structure of [Ag(4-benzoylpyridine) 2 ](NO 3 ).H 2 O revealed the monomeric structure of this complex [62].
In this regard, thiocyanate (SCN − ) is frequently used as a bridging ligand for creating new silver clusters because of the strong Ag-S bond and the high ability of silver to form relatively stable coordination compounds with nitrogen a as donor atom [63][64][65][66][67], in addition to its various coordination modes (Figure 1) [68][69][70][71][72][73][74][75].The crystal structure of the simple silver(I) thiocyanate salt has been reported by Zhu and coworkers.Its X-ray structure revealed a 3D network via Ag-S bonds and weak Ag. ..Ag interactions where each Ag-atom has a T-shaped coordination environment [65].Also, the X-ray structure of the AgSCN adducts with pyridine and other heterocyclic ligands was reported in the literature to have an oligo-nuclear structure [67], i.e., 1-, 2-and 3D polymeric networks that use AgSCN fragments as their building blocks [65,73,74].
In the light of the interesting structural and supramolecular structure properties of Ag(I) thiocyanato complexes, we report herein the synthesis of two new Ag(I)-CPs with 4-benzoyl pyridine (4BP) (Figure 2), using thiocyanate as a linker.The structure of the synthesized complexes was verified using single-crystal X-ray diffraction analysis.In addition, Hirshfeld calculations were used to investigate the supramolecular architectures of the studied complexes.In the light of the interesting structural and supramolecular structure properties of Ag(I) thiocyanato complexes, we report herein the synthesis of two new Ag(I)-CPs with 4-benzoyl pyridine (4BP) (Figure 2), using thiocyanate as a linker.The structure of the synthesized complexes was verified using single-crystal X-ray diffraction analysis.In addition, Hirshfeld calculations were used to investigate the supramolecular architectures of the studied complexes.

Synthesis and Characterizations
The X-ray structures of the Ag(I) complexes with 4-benzoylpyridine with different anions such as CF3COO − and NO3 − were previously reported in the literature [61,62].The former complex [Ag(4BP)2]2(CF3COO)2 is dinuclear through a strong argentophilic interaction connecting the two [Ag(4BP)2] cationic units [61] while the latter [Ag(4BP)2](NO3).H2O is monomeric [62].In both cases, the 4-benzoylpyridine molecule is acting as a monodentate ligand via its pyridine N-atom, and no close contacts were found between the Ag(I) ion and the carbonyl group.For [Ag(4BP)2]2(CF3COO)2, the nonpolar C•••H (26.2%) and the polar O•••H (15.6%) interactions were found to be the most important in the molecular packing.In this work, we present the synthesis of two new Ag(I) complexes with 4-benzoylpyridine (4BP) in the presence of thiocyanate (SCN − ) as a bridging  In the light of the interesting structural and supramolecular structure properties of Ag(I) thiocyanato complexes, we report herein the synthesis of two new Ag(I)-CPs with 4-benzoyl pyridine (4BP) (Figure 2), using thiocyanate as a linker.The structure of the synthesized complexes was verified using single-crystal X-ray diffraction analysis.In addition, Hirshfeld calculations were used to investigate the supramolecular architectures of the studied complexes.

Synthesis and Characterizations
The X-ray structures of the Ag(I) complexes with 4-benzoylpyridine with different anions such as CF3COO − and NO3 − were previously reported in the literature [61,62].The former complex [Ag(4BP)2]2(CF3COO)2 is dinuclear through a strong argentophilic interaction connecting the two [Ag(4BP)2] cationic units [61] while the latter [Ag(4BP)2](NO3).H2O is monomeric [62].In both cases, the 4-benzoylpyridine molecule is acting as a monodentate ligand via its pyridine N-atom, and no close contacts were found between the Ag(I) ion and the carbonyl group.For [Ag(4BP)2]2(CF3COO)2, the nonpolar C•••H (26.2%) and the polar O•••H (15.6%) interactions were found to be the most important in the molecular packing.In this work, we present the synthesis of two new Ag(I) complexes with 4-benzoylpyridine (4BP) in the presence of thiocyanate (SCN − ) as a bridging

Synthesis and Characterizations
The X-ray structures of the Ag(I) complexes with 4-benzoylpyridine with different anions such as CF 3 COO − and NO 3 − were previously reported in the literature [61,62].The former complex [Ag(4BP) 2 ] 2 (CF 3 COO) 2 is dinuclear through a strong argentophilic interaction connecting the two [Ag(4BP) 2 ] cationic units [61] while the latter [Ag(4BP) 2 ](NO 3 ).H 2 O is monomeric [62].In both cases, the 4-benzoylpyridine molecule is acting as a monodentate ligand via its pyridine N-atom, and no close contacts were found between the Ag(I) ion and the carbonyl group.For [Ag(4BP) 2 ] 2 (CF 3 COO) 2 , the nonpolar C•••H (26.2%) and the polar O•••H (15.6%) interactions were found to be the most important in the molecular packing.In this work, we present the synthesis of two new Ag(I) complexes with 4-benzoylpyridine (4BP) in the presence of thiocyanate (SCN − ) as a bridging ligand.Schematic illustration for the synthesis of the two complexes is shown in Scheme 1.The two complexes were prepared using almost the same reagents, which are AgNO 3 , 4BP and NH 4 SCN.The only difference is the addition of 1:1 (v/v) HNO 3 in the synthesis of 2. After mixing, the resulting clear solutions were left for slow evaporation at room temperature.After a few days, both complexes were formed in crystalline forms, which are suitable for single-crystal X-ray diffraction analysis.Based on the CIF data, the Hirshfeld calculations were used to investigate the intermolecular interactions of the studied complexes.
1.The two complexes were prepared using almost the same reagents, which are AgNO3, 4BP and NH4SCN.The only difference is the addition of 1:1 (v/v) HNO3 in the synthesis of 2. After mixing, the resulting clear solutions were left for slow evaporation at room temperature.After a few days, both complexes were formed in crystalline forms, which are suitable for single-crystal X-ray diffraction analysis.Based on the CIF data, the Hirshfeld calculations were used to investigate the intermolecular interactions of the studied complexes.
Scheme 1. Synthesis of the two complexes, 1 and 2.

X-ray Crystal Structure Description of [Ag(4BP)(SCN)]n (1)
The structure of complex 1 has been revealed using single-crystal X-ray crystallography to be [Ag(4BP)(SCN)]n.It crystallizes in the orthorhombic system with the Pna21 space group and Z = 4.The unit cell parameters are a = 27.2079(9)Å, b = 6.0833(2)Å and c = 7.5732(2) Å while the unit cell volume equals 1253.47(7)Å 3 .The asymmetric unit consists of one [Ag4BP(SCN)] unit (Figure 3a).The structure of the title complex is approved to have a 2D polymeric structure via the Ag-N and Ag-S interactions between the Ag(I) and the bridged SCN − group.

X-ray Crystal Structure Description of [Ag(4BP)(SCN)] n (1)
The structure of complex 1 has been revealed using single-crystal X-ray crystallography to be [Ag(4BP)(SCN)] n .It crystallizes in the orthorhombic system with the Pna2 1 space group and Z = 4.The unit cell parameters are a = 27.2079(9)Å, b = 6.0833(2)Å and c = 7.5732(2) Å while the unit cell volume equals 1253.47(7)Å 3 .The asymmetric unit consists of one [Ag4BP(SCN)] unit (Figure 3a).The structure of the title complex is approved to have a 2D polymeric structure via the Ag-N and Ag-S interactions between the Ag(I) and the bridged SCN − group.
temperature.After a few days, both complexes were formed in crystalline forms, which are suitable for single-crystal X-ray diffraction analysis.Based on the CIF data, the Hirshfeld calculations were used to investigate the intermolecular interactions of the studied complexes.
Scheme 1. Synthesis of the two complexes, 1 and 2.
Each thiocyanate anion exhibits a µ 1,1,3 -(S,S,N-) bridging mode, which binds three Ag(I) centers leading to a boat-like ten-membered ring.These repeating units are fused together to generate a 2D wavy-like structure extended along the ac plane (Figure 4a).As a result, each sulfur atom connects two silver atoms, one from its own unit and the other from another adjacent unit, leading to zig-zag chains extended along the c-direction, where the Ag-S-Ag angle is 155.04(4)• .These polymeric chains are further connected by the coordination interaction between the Ag(I) ion and N-atom from the third thiocyanate group, which extends the coordination polymer along the b-direction leading to the 2D polymeric structure shown in Figure 4b.The angles of the thiocyanate groups are nearly linear (179.7(4)• and 158.2(3) • for S1-C1-N1 and C1 ## -N1 ## -Ag1, respectively) while the Ag1-S1-C1 acquires bent conformation, with angles 96.34 (12) • for Ag1-S1-C1 and 94.97 (11) • for Ag1-S1 # -C1 # .These results are consistent with the mesomeric structure of the thiocyanate group [69,75].The 4BP organic ligand acts as a terminal monodentate ligand via the pyridine N-atom and thus is not included in the polymer expansion but is found located above and below the polymeric zig-zag chains (Figure 5).

X-ray Crystal Structure Description of {(4BP-H) + [Ag(SCN)2] − }n (2)
The crystal structure of complex 2 consists of the anionic complex [Ag(SCN)2] − , which forms a one-dimensional polymeric structure, in addition to the protonated 4BP cation (4BP-H) + as an outer sphere.The compound crystallizes in the triclinic system with the space group P-1 and Z = 2.The unit cell parameters are a = 6.0975(2)Å, b = 8.7626(4) Å, c = 14.6204(6)Å, α = 95.010(2)° and β = 100.1270(10)°while the unit cell volume is 765.80(5)Å 3 .The asymmetric unit and the coordination geometry of the Ag(I) together with the numbering scheme are shown in Figure 6.The asymmetric unit is composed of one 4BP-H + and one [Ag(SCN)2] − anion.In this complex, the N-atom (N3) from the 4BP is found protonated and is not involved in any coordination interaction with the Ag(I) ion.

X-ray Crystal Structure Description of {(4BP-H
The crystal structure of complex 2 consists of the anionic complex [Ag(SCN) 2 ] − , which forms a one-dimensional polymeric structure, in addition to the protonated 4BP cation (4BP-H) + as an outer sphere.The compound crystallizes in the triclinic system with the space group P-1 and Z = 2.The unit cell parameters are a = 6.0975(2)Å, b = 8.7626(4) Å, c = 14.6204(6)Å, α = 95.010(2)• and β = 100.1270(10) • while the unit cell volume is 765.80(5)Å 3 .The asymmetric unit and the coordination geometry of the Ag(I) together with the numbering scheme are shown in Figure 6.The asymmetric unit is composed of one 4BP-H + and one [Ag(SCN) 2 ] − anion.In this complex, the N-atom (N3) from the 4BP is found protonated and is not involved in any coordination interaction with the Ag(I) ion.
In the anionic part of this complex, the crystallographically unique Ag1 center is tetracoordinated by four thiocyanate groups via the three S-atoms S1, S1 # and S2 in addition to the N-atom N2 ## .The S(1)C( 1)N(1) − exhibit a µ 1,1 -mode while the S(2)C( 2)N(2) − exhibit a µ 1,3 -mode.The main geometrical parameters of the [Ag(SCN) 2 ] − anion are depicted in Table 2.The Ag-S distances range from 2.5747(6) to 2.6788(7) Å while the Ag-N bond distance is 2.213(2) Å.The angles around the silver atom are in the range from 99.980 (19) • to 132.38(8) • , revealing a distorted tetrahedral coordination geometry.As a result of the end-to-end (µ 1,3 -) bonding mode of the S(2)C( 2)N(2) − , the anionic part of the complex formed a one-dimensional polymeric chain running along the a-direction while the two thiocyanate groups with the (µ 1,1 -) bonding mode bi-bridge two Ag(I) centers (Figure 7).As a result, the anionic chain can more easily be considered as a lengthwise stacking of the [(Ag) 2 (SCN) 2 ] − dinuclear units.The Ag. ..Ag separation in the dinuclear unit is 3.379(4) Å, which is a little bit shorter than the sum of the van der Waals radii of two silver atoms (3.44 Å) [23], indicating weak argentophilic interactions, unlike the [Ag(4BP) 2 ] 2 (CF 3 COO) 2 complex in which the Ag-Ag distance is short 3.0740(2) Å, indicating a strong argentophilic interaction, which leads to the dinuclear complex.In the anionic part of this complex, the crystallographically unique Ag1 center is tetra-coordinated by four thiocyanate groups via the three S-atoms S1, S1 # and S2 in addition to the N-atom N2 ## .The S(1)C( 1 2)N(2) − , the anionic part of the complex formed a one-dimensional polymeric chain running along the a-direction while the two thiocyanate groups with the (µ1,1-) bonding mode bi-bridge two Ag(I) centers (Figure 7).As a result, the anionic chain can more easily be considered as a lengthwise stacking of the [(Ag)2(SCN)2] − dinuclear units.The Ag…Ag separation in the dinuclear unit is 3.379(4) Ǻ, which is a little bit shorter than the sum of the van der Waals radii of two silver atoms (3.44 Ǻ) [23], indicating weak argentophilic interactions, unlike the [Ag(4BP)2]2(CF3COO)2 complex in which the Ag-Ag distance is short 3.0740(2) Ǻ, indicating a strong argentophilic interaction, which leads to the dinuclear complex.
The cationic part (4BP-H) + of complex 2 acts as the templating agent that fills the space between the 1D anionic polymer.On the other hand, the 2D supramolecular framework of the complex is constructed mainly via the C-H. ..S interactions.These interactions occur between the carbon atom (C7) of the pyridine moiety in the (4BP-H) + as the hydrogen bond donor and the µ 1,1 -thiocyanato S-atom (S1) as the hydrogen bond acceptor and between the C12-H12 from the phenyl moiety of the (4BP-H) + cation and S2 of the µ 1,3 -thiocyanato group (Figure 8).The C7. ..S1 and C12. ..S2 contact distances are 3.692 Å and 3.639 Å, respectively, while the H7. ..S1 and H12. ..S2 distances are 2.900 Å and 2.908 Å, respectively.Moreover, there is a significant N3-H3. ..N1 hydrogen-bonding interaction between the protonated N-atom (N3) of the (4BP-H) + as the hydrogen bond donor and the freely uncoordinated N-atom (N1) from the µ 1,1 -thiocyanate group as the hydrogen bond acceptor (Figure 8).The H3. ..N1 and N3. ..N1 distances are 1.880 Å and 2.723 (3) Å, respectively.The cationic part (4BP-H) + of complex 2 acts as the templating agent that fills the space between the 1D anionic polymer.On the other hand, the 2D supramolecular framework of the complex is constructed mainly via the C-H…S interactions.These interactions occur between the carbon atom (C7) of the pyridine moiety in the (4BP-H) + as the hydrogen bond donor and the µ1,1-thiocyanato S-atom (S1) as the hydrogen bond acceptor and between the C12-H12 from the phenyl moiety of the (4BP-H) + cation and S2 of the µ1,3thiocyanato group (Figure 8).The C7…S1 and C12…S2 contact distances are 3.692 Å and 3.639 Å, respectively, while the H7…S1 and H12…S2 distances are 2.900 Å and 2.908 Å, respectively.Moreover, there is a significant N3-H3…N1 hydrogen-bonding interaction between the protonated N-atom (N3) of the (4BP-H) + as the hydrogen bond donor and the freely uncoordinated N-atom (N1) from the µ1,1-thiocyanate group as the hydrogen bond acceptor (Figure 8).The H3…N1 and N3…N1 distances are 1.880 Å and 2.723 (3) Å, respectively.

Analysis of Molecular Packing
The crystalline polymeric silver complexes 1 and 2 have a well-ordered arrangement that maintains the stability of the crystal through a set of interactions.These interactions involve primary bonds (covalent bonds) and secondary bonds (van der Waals, hydrogen bonds, Ag•••Ag interactions, π-π stacking, etc.).A leading method for finding and analyz-

Analysis of Molecular Packing
The crystalline polymeric silver complexes 1 and 2 have a well-ordered arrangement that maintains the stability of the crystal through a set of interactions.These interactions involve primary bonds (covalent bonds) and secondary bonds (van der Waals, hydrogen bonds, Ag•••Ag interactions, π-π stacking, etc.).A leading method for finding and analyzing all potential interactions that affect a crystal structure's stability is Hirshfeld topology analysis.Figure 9 shows the Hirshfeld surface mapped with the d norm properties along with the neighboring molecules involved in the closest contacts.The red and blue areas in the d norm map represent contacts shorter and longer than the sum of the van der Waals radii of the contacting atoms.Figure 10 illustrates the 2D fingerprint (FP) plots of the important interactions in the [Ag(4BP)(SCN)] n complex (1).The polymeric Ag-S (5.1%) and Ag-N (5.7%) interactions appear as intense red spots in the dnorm map (Figure 9) and as two distinct sharp spikes in the FP plot (Figure 10), indicating that these coordination interactions have great significance for the extension of the polymeric chain structure and in the stability of complex 1 as well.Additionally, other contacts such as C…H and O…H are important for the crystal stability of complex 1.These interactions represent 34.2% and 10.7% of the total Hirshfeld surface area for this complex.These interactions occur between the adjacent organic ligand (4BP) moieties.The C2…H9 and O1…H5 are the shortest interactions, where their corresponding distances are 2.741 Å and 2.592 Å, respectively.The polymeric Ag-S (5.1%) and Ag-N (5.7%) interactions appear as intense red spots in the dnorm map (Figure 9) and as two distinct sharp spikes in the FP plot (Figure 10), indicating that these coordination interactions have great significance for the extension of the polymeric chain structure and in the stability of complex 1 as well.Additionally, other contacts such as C…H and O…H are important for the crystal stability of complex 1.These interactions represent 34.2% and 10.7% of the total Hirshfeld surface area for this complex.These interactions occur between the adjacent organic ligand (4BP) moieties.The C2…H9 and O1…H5 are the shortest interactions, where their corresponding distances are 2.741 Å and 2.592 Å, respectively.Also, the supramolecular structure of the [Ag(4BP)(SCN)]n complex is affected by other numerous weak interactions.Figure 11 displays a summary of all contacts and their contributions to the molecular packing of this complex.The significant C…H (34.2%), hydrogenic H…H (16.4%) and N…H (12.5%) interactions are the most frequent interactions.The polymeric Ag-S (5.1%) and Ag-N (5.7%) interactions appear as intense red spots in the d norm map (Figure 9) and as two distinct sharp spikes in the FP plot (Figure 10), indicating that these coordination interactions have great significance for the extension of the polymeric chain structure and in the stability of complex 1 as well.Additionally, other contacts such as C. ..H and O. ..H are important for the crystal stability of complex 1.These interactions represent 34.2% and 10.7% of the total Hirshfeld surface area for this complex.These interactions occur between the adjacent organic ligand (4BP) moieties.The C2. ..H9 and O1. ..H5 are the shortest interactions, where their corresponding distances are 2.741 Å and 2.592 Å, respectively.Also, the supramolecular structure of the [Ag(4BP)(SCN)] n complex is affected by other numerous weak interactions.Figure 11  For the compound {(4BP-H) + [Ag(SCN)2] − }n (2), the dnorm map and the 2D fingerprint plots are presented in Figures 12 and 13, respectively.As in 1, the polymeric Ag-S and Ag-N interactions appear as intense red spots in the dnorm map and as two distinct sharp spikes in the FP plot.Their respective contributions are 3.5% and 5.3%, respectively.It revealed the polymeric nature of this compound through coordination interactions between the Ag(I) ion and the thiocyanato sulfur and nitrogen atoms, which form the 1D polymeric chain of this complex.As shown in Figure 12, the dnorm map shows other red spots related to the N…H, S…H, C…O and Ag…Ag contacts, which are also important for the crystal stability of complex 2. As shown in Figure 12, there are two large and intense red spots corresponding to the N…H interactions that also appear as sharp spikes in the FP plot (15.3%) (Figure 13), revealing the importance of this interaction in the crystal stability of 2. The N…H interaction occurs between the uncoordinated N-atom (N1) of the µ1,1-thiocyanato group in the 1D polymeric chain of [Ag(SCN)2] − anion and the hydrogen atom (H3) of the protonated For the compound {(4BP-H) + [Ag(SCN) 2 ] − } n (2), the d norm map and the 2D fingerprint plots are presented in Figures 12 and 13, respectively.As in 1, the polymeric Ag-S and Ag-N interactions appear as intense red spots in the d norm map and as two distinct sharp spikes in the FP plot.Their respective contributions are 3.5% and 5.3%, respectively.It revealed the polymeric nature of this compound through coordination interactions between the Ag(I) ion and the thiocyanato sulfur and nitrogen atoms, which form the 1D polymeric chain of this complex.As shown in Figure 12 For the compound {(4BP-H) + [Ag(SCN)2] − }n (2), the dnorm map and the 2D fingerprint plots are presented in Figures 12 and 13, respectively.As in 1, the polymeric Ag-S and Ag-N interactions appear as intense red spots in the dnorm map and as two distinct sharp spikes in the FP plot.Their respective contributions are 3.5% and 5.3%, respectively.It revealed the polymeric nature of this compound through coordination interactions between the Ag(I) ion and the thiocyanato sulfur and nitrogen atoms, which form the 1D polymeric chain of this complex.As shown in Figure 12, the dnorm map shows other red spots related to the N…H, S…H, C…O and Ag…Ag contacts, which are also important for the crystal stability of complex 2. As shown in Figure 12, there are two large and intense red spots corresponding to the N…H interactions that also appear as sharp spikes in the FP plot (15.3%) (Figure 13), revealing the importance of this interaction in the crystal stability of 2. The N…H interaction occurs between the uncoordinated N-atom (N1) of the µ1,1-thiocyanato group in the 1D polymeric chain of [Ag(SCN)2] − anion and the hydrogen atom (H3) of the protonated  The S…H interaction appeared in the FP as wings and contributed to the crystal structure packing by 14.9%, indicating the importance of the interactions between the hydrogen atoms from the (4BP-H) + cation and the S-atoms of the µ1,1-(S1…H7 = 2.778 Å) and µ1,3-thiocyanato (S2…H12 = 2.798 Å) groups from the anionic complex part, leading to the extended 2D supramolecular framework.Moreover, the C…O interaction occurred between the adjacent (4BP-H) + cations where the C7…O2 distance is 2.916 Å.In addition, the argentophilic (Ag…Ag) interaction occurred in complex 2 (Ag1…Ag1 = 3.378 Å).On the other hand, the contribution of the C…C contact by 5.4% in the FP plot (Figure 13), along with the red/blue triangles and green flat area in the shape index (SI) and curvedness maps, respectively, confirm the existence of π-π stacking interactions between the parallel phenyl rings of the (4BP-H) + cation (Figure 14).The C11…C13 (3.712 Å) and C12…C12 (3.714 Å) are the shortest distances between the stacked phenyl rings.These distances are longer than twice the van der Waals radii (3.40 Å) of the carbon atoms, indicating rather weak π-π stacking interactions.As shown in Figure 12, there are two large and intense red spots corresponding to the N. ..H interactions that also appear as sharp spikes in the FP plot (15.3%) (Figure 13), revealing the importance of this interaction in the crystal stability of 2. The N. ..H interaction occurs between the uncoordinated N-atom (N1) of the µ 1,1 -thiocyanato group in the 1D polymeric chain of [Ag(SCN) 2 ] − anion and the hydrogen atom (H3) of the protonated 4BP in (4BP-H) + cation where the N1. ..H3 distance is 1.734Å.
The S. ..H interaction appeared in the FP as wings and contributed to the crystal structure packing by 14.9%, indicating the importance of the interactions between the hydrogen atoms from the (4BP-H) + cation and the S-atoms of the µ 1,1 -(S1. ..H7 = 2.778 Å) and µ 1,3 -thiocyanato (S2. ..H12 = 2.798 Å) groups from the anionic complex part, leading to the extended 2D supramolecular framework.Moreover, the C. ..O interaction occurred between the adjacent (4BP-H) + cations where the C7. ..O2 distance is 2.916 Å.In addition, the argentophilic (Ag. ..Ag) interaction occurred in complex 2 (Ag1. ..Ag1 = 3.378 Å).On the other hand, the contribution of the C. ..C contact by 5.4% in the FP plot (Figure 13), along with the red/blue triangles and green flat area in the shape index (SI) and curvedness maps, respectively, confirm the existence of π-π stacking interactions between the parallel phenyl rings of the (4BP-H) + cation (Figure 14).The other weak non-covalent interactions that occurred in complex 2 are shown in Figure 15.The hydrogenic H…H (21.9%),N…H (15.3%),S…H (14.9%) and C…H (14.8%) contacts were the most frequent interactions.

Material and Instrumentation
All chemicals were obtained from Sigma-Aldrich Company and used as received.A Perkin Elmer 2400 Elemental Analyzer (PerkinElmer, New York, NY, USA) was used to perform the CHN analyses.Additionally, the amount of Ag was determined using a Shimadzu atomic absorption spectrophotometer (AA-7000 series, Shimadzu, Ltd., Kyoto, Japan).

Synthesis of [Ag(4BP)(SCN)]n Complex (1)
An aqueous solution of silver(I) nitrate (170 mg, 1 mmol) in 10 mL was mixed with a saturated solution of ammonium thiocyanate followed by the addition of an ethanolic solution (10 mL) of 4BP (183.2 mg, 1 mmol).This mixture was left at room temperature and allowed to evaporate slowly.The other weak non-covalent interactions that occurred in complex 2 are shown in Figure 15.The hydrogenic H…H (21.9%),N…H (15.3%),S…H (14.9%) and C…H (14.8%) contacts were the most frequent interactions.

Material and Instrumentation
All chemicals were obtained from Sigma-Aldrich Company and used as received.A Perkin Elmer 2400 Elemental Analyzer (PerkinElmer, New York, NY, USA) was used to perform the CHN analyses.Additionally, the amount of Ag was determined using a Shimadzu atomic absorption spectrophotometer (AA-7000 series, Shimadzu, Ltd., Kyoto, Japan).

Synthesis of [Ag(4BP)(SCN)]n Complex (1)
An aqueous solution of silver(I) nitrate (170 mg, 1 mmol) in 10 mL was mixed with a saturated solution of ammonium thiocyanate followed by the addition of an ethanolic solution (10 mL) of 4BP (183.2 mg, 1 mmol).This mixture was left at room temperature and allowed to evaporate slowly.

Material and Instrumentation
All chemicals were obtained from Sigma-Aldrich Company and used as received.A Perkin Elmer 2400 Elemental Analyzer (PerkinElmer, New York, NY, USA) was used to perform the CHN analyses.Additionally, the amount of Ag was determined using a Shimadzu atomic absorption spectrophotometer (AA-7000 series, Shimadzu, Ltd., Kyoto, Japan).An aqueous solution of silver(I) nitrate (170 mg, 1 mmol) in 10 mL was mixed with a saturated solution of ammonium thiocyanate followed by the addition of an ethanolic solution (10 mL) of 4BP (183.2 mg, 1 mmol).This mixture was left at room temperature and allowed to evaporate slowly.Complex 1 was obtained as pale-yellow block crystals after 10 days.[Ag(4BP)(SCN)] n (1) An aqueous solution of silver(I) nitrate (170 mg, 1 mmol) in 10 mL was mixed with a saturated solution of ammonium thiocyanate followed by the addition of an ethanolic solution (10 mL) of 4BP (183.2 mg, 1 mmol).To the resulting mixture, 2 mL of 1:1 (v/v) aqueous solution of nitric acid was added.Complex 2 was obtained as colorless needle crystals after 6 days.{(4BP-H) +

X-ray Crystallography
The crystal structure of the two complexes was measured with the aid of Bruker APEX II machine employing graphite monochromator and MoKα radiation.Absorption corrections were performed using SADABS while all steps performed to solve the structure were executed using the SHELXTL program package [76].Table S1 (Supplementary Data) provides a summary of the crystallographic results.

Hirshfeld Surface Analysis
The program Crystal Explorer 17.5 [77] was used to analyze the various intermolecular interactions in the investigated silver complexes.

Conclusions
The supramolecular structures of the 2D [Ag(4BP)(SCN)] n (1) and 1D {(4BP-H) + [Ag(SC N) 2 ] − } n (2) coordination polymers are presented.Both complexes were prepared from the reaction of 4-benzoyl pyridine (4BP) with AgNO 3 in the presence of thiocyanate as a linker.As shown from the X-ray structure analysis of both complexes, the 4BP does not participate in expanding the polymeric structure.In complex 1, it acts as a N-donor monodentate ligand while in 2 it does not participate in coordination and was found monoprotonated (4BP-H) + .The thiocyanate anion displays different coordination modes in complexes 1 and 2, which affects the interconnection of the (AgSCN) n fragments and the propagation of the network structure in the different dimensions.In the case of complex 1, the SCN − exhibits a µ 1,13 -bonding mode, while in 2 there are two types of bonding modes, which are the µ 1,1and µ 1,3 -types.As a result, 2D and 1D polymeric structures are obtained for complexes 1 and 2, respectively.The supramolecular structure aspects of both complexes were analyzed quantitatively using Hirshfeld analysis.The non-covalent C. ..H and O. ..H interactions are the most significant contacts in 1 where the percentages of these interactions are 34.2% and 10.7%, respectively.In 2, the N. ..H (15.3%), S. ..H (14.9%) and C. ..O (3.2%) contacts are the most significant.Additionally, the hydrogenic H. ..H interactions largely contributed to the packing of complexes 1 (16.4%) and 2 (21.9%).

Figure 4 .
Figure 4.The zigzag-like (a) showing the two-dimensional polymeric structure (b) of complex 1 formed by the µ1,1,3-thiocyanate bridging ligand, viewed along two different axes.The 4BP and Hatoms are omitted for clarity.

Figure 4 .
Figure 4.The zigzag-like (a) showing the two-dimensional polymeric structure (b) of complex 1 formed by the µ 1,1,3 -thiocyanate bridging ligand, viewed along two different axes.The 4BP and H-atoms are omitted for clarity.

Figure 5 .
Figure 5.The monodentate 4BP ligand units are found above and below the zig-zag chains of the 2D polymer.

Figure 5 .
Figure 5.The monodentate 4BP ligand units are found above and below the zig-zag chains of the 2D polymer.

Figure 6 .
Figure 6.The asymmetric unit (a) and the coordination geometries of the silver (I) ion (b) in the polymeric structure of compound 2. Symmetry codes: # 2 − x, −y, −z and ## −1 + x, y, z.

Figure 10 .
Figure 10.Hirshfeld 2D fingerprint plots for the most significant (Ag-N, Ag-S, O…H and C…H) interactions and other contacts (H…H and N…H), which have a high percentage in complex 1.

Figure 13 .
Figure 13.Hirshfeld 2D fingerprint plots of the most significant (Ag-N, Ag-S, N…H, S…H, C…O and Ag…Ag) interactions and other contacts (H…H, C…H, O…H and C…C) that contribute with a high percentage to the stability of complex 2.

18 Figure 14 .
Figure 14.Full SI (a) and curvedness (b) maps for complex 2 showing the presence of the π-π interaction.