The first coordination compounds of OP[NC4H8O]3 phosphoric triamide ligand: structural study and Hirshfeld surface analysis of SnIV and MnII complexes

Article abstract of DOI:10.1080/00958972.2017.1295139

The first X-ray crystal structures of coordination compounds of OP[NC₄H₈O]₃ phosphoric triamide (L) are investigated in Cl₂(CH₃)₂Sn(trans-L)₂ (1) and [Mn(H₂O)₄(trans-L)₂]Cl₂·2H₂O (2) as models of molecular and salt complexes for Hirshfeld surface (HS)-based analysis. The crystal packing of 1 includes weak interactions, while in the salt complex 2, a 2-D aggregate, along the (001) plane, is mediated by normal O–H?Cl and O–H?O hydrogen bonds. In the Hirshfeld study, the crystal cohesions of 1 and 2 are recognized via H?H, O?H/H?O, and Cl?H/H?Cl contacts. Among these interactions, hydrogen bonds O–H?Cl occur in the salt structure of 2, as well as some weaker hydrogen interactions as C–H?O (1 and 2), C–H?Cl (1), and O–H?O (2). The full fingerprint plots have nearly symmetric shapes for two independent molecules of 1, while an asymmetric shape appears for the cationic component of 2. To extract more detailed information on close intermolecular contacts, the molecular surface of the previously reported structure L was also mapped. The structure 2 is the first monomeric octahedral Mn(II)–phosphoric triamide complex reported so far. Furthermore, the HS analysis of 2 is the first such study on a cation–anion complex structure including phosphoric triamide ligand.

Full text of DOI:10.1080/00958972.2017.1295139

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: http://www.tandfonline.com/loi/gcoo20
The first coordination compounds of OP[NC4H8O]3
phosphoric triamide ligand: Structural study
and Hirshfeld surface analysis of SnIV and MnII
complexes
Mehrdad Pourayoubi, Atekeh Tarahhomi, James a. Golen & Arnold l.
Rheingold
To cite this article: Mehrdad Pourayoubi, Atekeh Tarahhomi, James a. Golen & Arnold l.
Rheingold (2017): The first coordination compounds of OP[NC4H8O]3 phosphoric triamide ligand:
Structural study and Hirshfeld surface analysis of SnIV and MnII complexes, Journal of Coordination
Chemistry, DOI: 10.1080/00958972.2017.1295139
To link to this article: http://dx.doi.org/10.1080/00958972.2017.1295139
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Date: 21 February 2017, At: 02:51

Publisher: Taylor & Francis
Journal: Journal of Coordination Chemistry
DOI: http://dx.doi.org/10.1080/00958972.2017.1295139
The first coordination compounds of OP[NC4H8O]3 phosphoric triamide
ligand: Structural study and Hirshfeld surface analysis of
SnIV and MnII complexes
MEHRDAD POURAYOUBI†, ATEKEH TARAHHOMI‡, JAMES A. GOLEN§ and
ARNOLD L. RHEINGOLD§
†Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad 9177948974, Iran
‡Department of Chemistry, Semnan University, Semnan 35351-19111, Iran
§Department of Chemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
The first X-ray crystal structures of coordination compounds of OP[NC4H8O]3 phosphoric
triamide (L) are investigated in Cl2(CH3)2Sn(trans-L)2 (1) and [Mn(H2O)4(trans-L)2]Cl2·2H2O (2)
as models of molecular and salt complexes for Hirshfeld surface-based analysis. The crystal
packing of 1 includes weak interactions, while in the salt complex 2, a two-dimensional
aggregate, along the (001) plane, is mediated by normal O–H…Cl and O–H…O hydrogen bonds.
In the Hirshfeld study, the crystal cohesion of 1 and 2 are recognized via H…H, O…H/H…O
and Cl…H/H…Cl contacts. Among these interactions, hydrogen bonds O–H…Cl occur in the
salt structure of 2, as well as some weaker hydrogen interactions as C–H…O (1 and 2), C–H…Cl
(1) and O–H…O (2). The full fingerprint plots have nearly symmetric shapes for two
independent molecules of 1, while an asymmetric shape appears for the cationic component of 2.
To extract more detailed information on close intermolecular contacts, the molecular surface of
the previously reported structure L was also mapped. The structure 2 is the first monomeric
octahedral Mn(II)-phosphoric triamide complex reported so far. Furthermore, the Hirshfeld
surface analysis of 2 is the first such study on a cation-anion complex structure including
phosphoric triamide ligand.
Keywords: X-ray crystallography; Phosphoric triamide; Hydrogen bond; Symmetry-independent
molecule; Hirshfeld surface analysis
Corresponding author. Email: tarahhomi.at@semnan.ac.ir
1

1. Introduction
Phosphoric triamides (PTs) have received attention due to their diverse use as antioxidants [1],
Lewis base catalysts [2] and O-donor ligands [3-5]. Metal complexes of phosphoramide ligands
have diverse structures and importance of some metal complexes, like organotin(IV)-
phosphoramide complexes, in biological sciences as antifouling, antitumor and antimicrobial
agents [6-10]. MnII has almost not been studied in the phosphoric triamide coordination
chemistry, but offers a promising future as there has recently been much interest to the MnII
complexes as polymerization catalysts [11], and also for antibacterial [12] and anticancer
[13, 14] activities.
Intermolecular non-covalent interactions such as hydrogen bonds and weak contacts play
an important role in assembly of molecules/ions in crystals [15]; so that understanding of such
interactions in the crystal structures and controlling of the solid-state behavior of compounds is a
noteworthy goal of crystal engineering [16]. Study on such interactions helps to develop
procedures for preparation of compounds with desired properties and also to predict the
molecular assemblies and structural control of compounds.
Hirshfeld surface (HS) studies offer a resource for visualizing, exploring, analyzing and
quantifying intermolecular interactions in crystals with ease, rapidity and immediacy by
graphical representations based on three-dimensional HSs and related fingerprint plots (FPs)
[17-19]. Although, studying intermolecular interactions may be performed by different methods
or software programs, the HS-based method has gained prominence as a valuable graphical tool
for clarifying the details of crystalline packing.
Up to now, this method has been used to study intermolecular interactions in a few
organotin(IV)-phosphoric triamide complexes [5, 20]. Other metal phosphoric triamide
complexes have not been studied with Hirshfeld surface analysis. Study on organotin(IV)
complexes are limited to (NHC)(NCC)2P(O)-Sn and (NHC)3P(O)-Sn skeletons [5, 20].
In this paper, we present tris(morpholin-4-yl) phosphine oxide (OP[NC4H8O]3 = L) in the
synthesis of Cl2Sn(CH3)2(L)2 (1) and [Mn(H2O)4(L)2]Cl2·2H2O (2), which include six-coordinate
SnIV and MnII centers. We describe the close intermolecular contacts in the structures, and also
for previously reported structure of L, using the HS tool with the goal of enabling quantitative
comparison between intermolecular interactions in the crystal structures. HS analysis of the
2

MnII-phosphoric triamide complex studied here is the first such study on a non-tin metal
phosphoric triamide complex.
Based on the knowledge from the Cambridge Structural Database (CSD, version 5.37,
Feb. 2016 update [21]), 1 and 2 are the first coordination compounds of OP[NC4H8O]3. One
structure of a manganese(II)-phosphoric triamide complex with a Mn–{OP[N(C)(C)]3}2 segment
has been reported with the commercial ligand hexa-methyl phosphoric triamide (HMPA) (CSD
refcode VAYWEY [22]), in which Mn is located in a four-coordinate environment. The structure
of 2, reported here, is the first monomeric octahedral Mn(II)-phosphoric triamide complex.
Apart from HMPA, which were applied in the preparation of 33 organotin(IV) structures
[21], no other (NCC)3P(O)-based phosphoric triamide has been used for preparation of
organotin(IV)-phosphoric triamide structures. Due to extensive application of organotin(IV)
compounds in biosciences, especially as alternative to anti-cancer cisplatin-based drugs (with
high toxicities), this paper introduces a new water-soluble phosphoric triamide ligand which may
be useful to extend the organotin chemistry and possible future applications in biochemistry.
2. Experimental
2.1. Materials and measurements
All chemicals were of analytical grade, obtained from commercial sources and used without
purification. Infrared (IR) spectra were recorded on a Buck 500 scientific spectrometer using
KBr disks. Elemental analyses (C, H and N) were performed using a Thermo Finnigan Flash
1112EA elemental analyzer. Melting points were determined using an Electrothermal IA-9300
apparatus and are uncorrected.
2.2. Syntheses
For preparation of OP[NC4H8O]3, a solution of morpholine in dry acetonitrile was added
dropwise to a solution of P(O)Cl3 in the same solvent (6:1 molar ratio) at 273 K. After stirring
for 4 h, the solvent was removed in vacuo, and the crude product was used in complexation
reactions.
2.2.1. Syntheses of trans-dichlorido-trans-dimethyl-trans-bis[tris(morpholin-4-yl) phosphine
oxide-O]tin(IV), Cl2Sn(CH3)2(OP[NC4H8O]3)2 (1). A solution of Sn(CH3)2Cl2 (1 mmol) in
3

methanol (5 ml) was added dropwise to an excess of ligand (2.5 mmol) solution in methanol
(15 ml). The clear solution was stirred under reflux for 48 h. Colorless crystals were obtained
after a few days at room temperature. Yield: 58%. M.p. 205 °C. Anal. Calc. for
C26H54Cl2N6O8P2Sn (830.31): C, 37.61; H, 6.55; N, 10.12. Found: C, 37.70; H, 6.52; N, 10.09.
IR (KBr, cm−1): 2966, 2908, 2851, 1654, 1450, 1363, 1299, 1260, 1162, 1114, 1025, 967, 915,
843, 786, 731.
2.2.2. Syntheses of tetraaqua-trans-bis[tris(morpholin-4-yl) phosphine oxide-
O]manganese(II) dichloride dihydrate, [Mn(H2O)4(OP[NC4H8O]3)2]Cl2·2H2O (2). A
solution of MnCl2·4H2O (1 mmol) in methanol/acetonitrile (15 ml; 1:3 v/v) was added dropwise
to an excess of ligand (2.5 mmol) solution in methanol (15 ml). The clear solution was stirred
under reflux for 48 h. Colorless crystals were obtained after a few days at room temperature.
Yield: 52%. M.p. 89 °C. Anal. Calc. for C24H60Cl2N6O14P2Mn (844.56): C, 34.13; H, 7.16; N,
9.95. Found: C, 34.37; H, 7.04; N, 9.98. IR (KBr, cm−1): 3391, 3242, 2968, 2902, 2852, 1654,
1447, 1386, 1301, 1259, 1200, 1106, 1025, 966, 920, 843, 731.
2.3. X-ray measurements
A suitable single crystal for 1 and 2 was selected for X-ray diffraction experiments and mounted
on a glass fiber. Details of crystal data and structure refinement have been provided in table 1.
X-ray data for 1 and 2 were collected on a Bruker APEX2 CCD system [23, 24] using
Mo Kα radiation. Data were corrected for absorption by SADABS [24]. Structures were solved
by direct methods, and all non-hydrogen atoms were refined by Fourier full matrix least squares
on F2. All hydrogens were placed in calculated positions with appropriate riding parameters for 1
and 2; that is, C–H distances of 0.990 Å for CH2 and 0.980 Å for CH3 with 1.20 and 1.50 Ueq of
parent carbon. For 2, hydrogens of water bonded to Mn were found from a Fourier difference
map and were refined with distance restraints of 0.87 (0.02) Å for O–H and 1.47 (0.02) Å for
H…H of HO–H angle. Hydrogens on solvent waters were not found but were included in
chemical formula to obtain correct formula.
In 1, systematic absences indicated a centrosymmetric space group (P21/c) and structural
solution was refined with two independent molecules in the asymmetric unit with portions of one
molecule being disordered. In Sn1', four of the morpholine rings were treated as being disordered
4

over two positions; that is, for rings N2′ and N2A (0.6920/0.3080), for rings N3′ and N3A
(0.7187/0.2813), for rings N4′ and N4A (0.8184/0.1816), and for rings N5′ and N5A
(0.7652/0.2348). Equal displacement parameter constraints were used for N, O, and C of these
rings and distant restraints for P–N of 1.65 (0.02) Å, N–C of 1.47 (0.02) Å, C–C of 1.50 (0.02) Å
and C–O of 1.44 (0.02) Å. For this structure, there is also another structural solution provided by
SIR97 [25] and some runs of Superflip [26] where the asymmetric unit contains one whole
molecule and parts of two molecules with these molecular parts located in special positions. Both
structural models, the one with two molecules in the asymmetric unit and the one with one whole
molecule and two fractional molecular parts, give similar results. The authors prefer the structure
model with two independent molecules because this model is provided by newer versions of SIR
as well as most of the Superflip runs.
Structure 2 exhibited chloride and water molecules near symmetry elements and were
refined with occupation factors of Cl and O of water at 50% and with the suppression of the
generation of special position constraints.
SHELXTL [27], DIAMOND [28] and Mercury [29] programs were used for making the
stereo drawings.
2.4. Hirshfeld surface analysis
3D Hirshfeld surfaces (HSs) of 1 and the complex dication of 2 were generated using
CrystalExplorer 3.1 [30] which accepts a structure input file in CIF format. Bond lengths to
hydrogens were set to standard values (C–H = 1.083 Å and O–H = 0.983 Å) during calculations
because internal consistency is important when comparing one structure with another. The
normalized contact distances dnorm based on van der Waals radii [17] were mapped into the HSs
(from –0.299 Å to +1.592 Å for 1 and from –0.714 Å to +1.339 for the complex dication of 2).
Close intermolecular interactions identified as red spots on the dnorm HSs are listed in table 2. For
molecule Sn1' of 1, the disorder in the morpholine rings was modeled by running the HS analysis
for this molecule, beside both possible orientations separately. Then, one orientation of
morpholine rings was selected and modeled as fully occupied.
The normalized contact distance dnorm is defined based on pair distances de, di (the
distances from a point on the surface to the nearest atom outside and inside the surface,
respectively) and van der Waals radii of the atom, given by equation 1.
5

=
+
(1)
A red-blue-white color scheme is employed for the identification of the regions of
particular importance to intermolecular interactions, where intermolecular contacts are shorter or
longer or close to van der Waals separations introduced by negative (red color) or positive (blue
color) or zero (white color) values of dnorm, respectively.
The HS fingerprint plots (FPs) [19, 31] were constructed from the pair distance de, di for
each individual surface spot which quantitatively summarize the information provided by the
generated HSs in the two-dimensional grid histograms. The blue-green-red color coding in the
FP represents the frequency of occurrence of any given pair of di, de as low, medium and high
frequent occurrence, respectively. For further detailed analysis, the ‘decomposed’ FPs can be
used that allow isolation of any given interaction, where only the relevant interactions are
colored. These decomposed plots include the reciprocal X…H/H…X contacts in which X is
located inside (for X…H/de < di) or outside (for H…X/de > di) the generated HS as an H-atom
acceptor. The complementary regions, where one molecule is a donor (de > di) and the other as
an acceptor (de < di), can be also identified in the FPs [32].
3. Results and discussion
3.1. Structural description
The molecular structures of 1 and 2 are shown in figures 1 and 2, respectively. Selected bond
lengths and angles are presented in table 3. For 1, the asymmetric unit is composed of two
symmetry-independent molecules Sn1 and Sn1', while 2 includes one-half of the complex
dication, one chloride and one H2O molecule. In the dication, MnII is located on an inversion
center. Moreover, 2 has chlorides and water molecules disordered through near symmetry
elements (figure 2).
In 1 and 2, the metal has distorted octahedral coordination with two PT ligands trans to
each other. For 2, MnII is also coordinated with four H2O molecules; the Cl anions are not
coordinated. Polyhedra of 1 and 2 are shown in figures 3 and 4.
In both 1 and 2, the morpholine rings have a chair conformation and P atoms in the
ligands have a distorted tetrahedral environment. In 1, the P═O bond length coordinated to a
6

metal center is slightly increased in comparison with free OP[NC4H8O]3 (BIVYAG [33]:
1.4891(1) Å), while in 2, it is slightly decreased (table 3). The P–N bond lengths in both
complexes (table 3) do not show significant differences with the values of free OP[NC4H8O]3
(the P–N bond lengths = 1.6375(1) Å, 1.6385(1) Å and 1.7168(2) Å).
The Sn–O, Sn–Cl and Sn–C bond lengths and the Sn–O–P bond angles of 1 are within
expected values [9, 18]. There is no analogous monomeric octahedral Mn(II)-phosphoric
triamide complex deposited, and the one Mn(II)-phosphoric triamide in the CSD is a four-
coordinate complex (VAYWEY [22]). The Mn―O(P) bond length of 2 (2.1103(14) Å) is longer
than that in the tetrahedral VAYWEY.
Bond valence sum (BVS) values for tin ions in Sn1 and Sn1' of 1 and for manganese in 2
were calculated as 4.155, 4.224 and 2.192, respectively, which are close to the formal oxidation
states of SnIV and MnII.
Structure 1 is devoid of strong hydrogen bonds due to lack of appropriate donors and
acceptors. In 2, the O–H units of coordinated H2O molecules take part in O–H…Cl and O–H…O
hydrogen bonds (table 4), which form a two-dimensional layer along the (001) plane (figure 5).
3.2. Analysis of intermolecular interactions by HSs and FPs
3.2.1. HS and FP of L. The dnorm HS and decomposed FPs for L are displayed in figure 6. The
red and pale red spots on HS correspond to the O…H/H…O and H…H contacts (table 2),
respectively. The O…H/H…O contacts reflect the C–H…O hydrogen bonds in which the
oxygens of NC4H8O or P═O are involved.
By inspecting decomposed FPs in figure 6, the highest proportions of interactions are
found for H…H contacts which cover a wide range of HS comprising 72.9% marked by the
points spread out in the center of FP. These contacts provide the closest interactions, with the
minimum di + de of 2.2 Å. The O…H/H…O contacts are illustrated as points in a relatively large
region of de, di distances (1.2 Å < de, di < 2.3 Å) on the related FP, containing two characteristic
spikes approaching (0.9 and 1.2) in the plot, and hence a closest contact near 2.1 Å. For the
decomposed H…H FP, the occurrence frequency of H…H contacts is increased in the region of
1.3 Å < de, di < 1.8 Å, manifested by color change from blue to green. For the decomposed
O…H/H…O FP, such color change is found in small region of 1.4 Å < de, di < 1.7 Å.
7

3.2.2. HSs and FPs of 1. The molecule Sn1' of 1 shows disorder in the morpholine rings; so, the
HSs were generated for possible major and minor components in connection with the fully
occupied Sn1. In figure 1, the major and minor components are labeled as suffixes "prime" and
"capital letter A", respectively. Figures 7 and 8 show the Hirshfeld surface maps of the major
disordered component, while the maps in figures 9 and 10 are related to Sn1 interacting with this
component. Furthermore, the HSs were generated for the minor component (figures S1 and S2)
and Sn1 (figures S3 and S4) separately interacting with each other. By comparing the two
models, the proportion of interactions showed changes of less than 0.2%; hence, for the
following discussion, the major disordered conformation of Sn1′ is treated as fully occupied in
connection with the molecule Sn1. The few differences observed in the shapes of FPs (as shown
in figures 7-10 and S1-S4) are caused by slightly different distribution of intermolecular
interactions.
The vivid red spots on the HSs of molecules Sn1 and Sn1' of 1 in figures 7 and 9 are due
to C–H…O hydrogen bonds. These hydrogen bonds arise from interactions between O of the
NC4H8O rings with the CH of the adjacent NC4H8O rings. There are also light red spots on HS
which reflect H…H contacts between hydrogens of neighboring NC4H8O rings, highlighted by
the orange dashed circles in figures 7 and 9. Some of these contacts are also very light or almost
white due to the longer H…H distances.
For the HS of Sn1', the most visible color scheme is a large deep red spot (marked by the
red arrow in figure 9) formed by the combined C…C and H…H contacts. These contacts which
represent the interactions between the same CH2 groups (H11C–C11'–H11D) of the NC4H8O
rings in two adjacent Sn1' molecules included one C11'…C11' and two H11C…H11D contacts
(table 2).
C–H…Cl hydrogen bonds are also seen on HSs of Sn1 and Sn1' molecules (figures 8 and
10) visualized by very light red spots or almost white areas, in which the hydrogens are related to
the NC4H8O groups (table 2).
By considering decomposed FPs in figures 7-10, all of them are nearly symmetric relative
to the plot diagonal with de = di values. The molecular interactions in these compounds are
predominantly of the H…H type which cover a wide range of HS comprising 71.1% in Sn1 and
71.6% in Sn1'. These H…H contacts marked by the points spread out in the center of the FP
provide the closest contacts, with the minimum di + de value of 2.2 Å. Moreover, the increases of
8

the occurrence frequencies for H…H contacts are evidenced by color change from blue to green
in the regions of de = di (≈ 1.2 – 1.7 Å for both molecules) on the plot diagonal.
The decomposed fingerprint plots of O…H/H…O contacts include 19.8% of total related
HS area for both molecules of 1 (figures 7 and 9). These contacts correspond to the C–H…O
hydrogen bonds (those described on the related dnorm HSs) which are illustrated as the scattered
points in the region of the middle, top left and bottom left sections of the plot with minimum
di + de values of 2.4 Å and 2.3 Å for Sn1 and Sn1', respectively. In O…H/H…O FP of Sn1, one
very short spike in the bottom left section of the plot (marked by red circle in figure 7) is visible.
The Cl…H and H…Cl contacts combined, represented as characteristic wings at the top
left (de > di, H…Cl) and bottom right (de < di, Cl…H) sections of the related plots in figures 8
and 10, comprise 9.1% and 8.6% for Sn1 and Sn1' molecules, respectively.
Finally, visual inspection of FPs in figures 7-10 affirms that although the nature of
intermolecular interactions in two independent molecules Sn1 and Sn1' of 1 are similar to each
other, there are subtle differences in the distribution of H…H and Cl…H/H…Cl contacts.
Such analyses were only investigated for four organotin(IV)-phosphoric triamide
complexes, I to IV in table 5, where a summary of analyses are gathered in a comparison with 1.
As the N–H unit exists in structures I, II and IV, the Cl…H/H…Cl contacts are associated to
both intermolecular N–H…Cl and C–H…Cl hydrogen bonds, different from 1 which only
includes CH…Cl interactions. In III, the N–H unit of the C(O)NHP(O) segment takes part in
intramolecular N–H…Cl–Sn hydrogen bonds. The N–H units in structures I, II and IV contribute
to the contacts manifested (as spikes and red spots). In the absence of N–H in 1, weak hydrogen
bonds show more participation in the contact. For I, II and IV, two sharp spikes correspond to
Cl…H/H…Cl contacts with de, di > 1.4 Å; while for III and 1, spikes are not visible on the
related FP due to longer Cl…H distances (for C–H…Cl hydrogen bonds), with de, di > 1.6 Å for
III and de, di > 1.7 Å for 1. The presence of other contacts are related to hydrogen acceptors
cooperating in the packing map. For example, in III, the O…H/H…O, F…H/H…F and
C…H/H…C contacts are also visible, due to the presence of a free O (non-coordinated), F and
unsaturated C as acceptors.
3.2.3. HS and FP of 2. The dnorm HS plot of the dication component of 2 and related
decomposed FPs are exhibited in figure 11. The O–H…Cl and O–H…O hydrogen bonds in the
9

crystal structure of 2 (figure 5, tables 2 and 4) can be easily discerned from the HS as large red
spots. The C–H…O hydrogen bonds from the interactions between the O atoms and CH groups
of the adjacent NC4H8O rings (table 2) are visible as light red spots due to the longer H…O
distances. No other characteristic contact is seen on the HS.
In figure 11, a visual inspection of decomposed FP for H…H contacts shows that it is
approximately symmetric relative to the plot diagonal with de = di values. FPs with asymmetric
shapes are seen for O…H/H…O and Cl…H/H…Cl contacts, where the decomposed FPs show
interactions between two different components, [Mn(H2O)4(OP[NC4H8O]3)2]2+ with non-
coordinated H2O molecule and Cl–. The O…H/H…O and Cl…H/H…Cl contacts are for the non-
charged O–H…O and the charged O–H…Cl hydrogen bonds, respectively. The donor OH
groups in both cases belong to coordinated H2O molecules and the acceptor O arises from non-
coordinated H2O molecules. Such asymmetric FPs are expected for structures that contain more
than one component (molecule/ion) [34] with interactions between the different species.
As expected, in asymmetric O…H/H…O FP of 2, the H…O contacts (19.8%)
demonstrate a higher proportion than the O…H contacts (10.4%), since the H…O contacts cover
the strong OH…O hydrogen bonds between the OH groups (of [Mn(H2O)4(OP[NC4H8O]3)2]2+)
and the O (of non-coordinated H2O) located inside and outside the generated HS, respectively.
The O…H contacts correspond to weak C–H…O hydrogen bonds between the CH NC4H8O
rings with O of the other NC4H8O rings. The mentioned H…O contacts are identified as a long
broad spike reaching down to near 1.7 Å, providing the minimum di + de values (figure 11). The
O…H contacts encompass the regions of the bottom half (relative to the diagonal plot) of the
related FP (de < di) including a very short thin spike reaching down to near 2.4 Å marked by a
red dashed circle in figure 11.
The asymmetric Cl…H/H…Cl FP only contains the H…Cl contacts with a proportion of
10.6% (0% for Cl…H contacts) acquired by the presence of uncoordinated chlorides (for
H…Cl/de > di) the generated HS as an H-atom acceptor versus the absence of chloride in inside
(for Cl…H/de < di). These H…Cl contacts are points in the regions of the top half of the FP
(de > di) relative to the diagonal plot, covering the charged hydrogen bonds O–H…Cl. These
regions are narrowed toward points with lower de + di values as a beak-like spike in the top left
corner of the FP.
10

Similar to 1, the highest proportions of contacts for 2, marked by the points spread out in
a large area of FP, are observed for H…H contacts (comprising 59.2%). Moreover, the frequency
of occurrence of H…H contacts increases in the regions of de = di (≈ 1.3 – 1.7 Å) on the plot
diagonal, shown as the bright areas colored from blue to green.
3.2.4. Comparison of HSs and FPs of 1 and 2 with free L. In the absence of any classical
hydrogen bond in the structure of L, the H…H and O…H/H…O contacts play decisive roles in
crystal packing, represented as red spots on the HS, and the O…H/H…O contacts are the weak
CH…O(═P/―C4H8N) hydrogen bonds. In HSs of 1 and 2, O…H/H…O contacts are visible as
red spots. Although, the minimum de, di values of O…H/H…O contacts are slightly enhanced
from de = di ≈ 0.9 Å in L to de = di ≈ 1.0 Å in 1. This is due to the non-availability of P═O for
hydrogen bond interaction in 1 as it takes part in coordination. In 1, O of OC4H8N takes part in
the O…H/H…O contacts, but have lower hydrogen bond acceptor capability with respect to the
P═O, reflected in the strength of hydrogen bonds formed. For 2, the cited minimum de, di values
of H…O contacts in L decline to de ≈ 0.9 Å/di ≈ 0.7 Å provided by strong O–H…O hydrogen
bonds formed. For the O…H contacts, which are related to weak C–H…O hydrogen bonds, the
minimum de, di values from free L (de = di ≈ 0.9 Å) to complex (de ≈ 1.0 Å and di ≈ 1.4 Å in 2)
increase.
The Cl…H/H…Cl contacts, besides the H…H and O…H/H…O, are the other
intermolecular contacts in the crystal structures of both 1 and 2 (manifested as light red spots on
the related HSs).
In all three structures (1, 2 and L), the H…H contacts have the most contribution
portions, due to the high proportions of hydrogen numbers.
Asymmetry about the plot diagonal is typical of the structures that contain more than one
component (molecule/ion). Thus, a symmetric FP is observed for L which includes only one
complete molecule in the asymmetric unit. For 1, nearly symmetric FPs are observed for two
symmetry independent molecules with the same formula, while for 2 with three different
components the FP is completely asymmetric.
11

4. Conclusion
The OP[NC4H8O]3 (L) phosphoric triamide was introduced as a water-soluble ligand and used
for preparation of two new coordination compounds. The 3D HSs and associated 2D FPs were
applied to expose a detailed investigation of intermolecular interaction networks in the new
structures Cl2(CH3)2Sn(trans-L)2 (1) and [Mn(H2O)4(trans-L)2]Cl2·2H2O (2) and also in the
previously reported structure of free L. The manganese(II) complex reported here is the first
octahedral Mn(II)–phosphoric triamide with an (NCC)3P(O) segment. HS analysis is the first
such analysis for a non-tin metal phosphoric triamide complex. The obtained results are: (i) The
H…H, O…H/H…O and Cl…H/H…Cl contacts play a significant role in the structures of 1 and
2, shown as red spots on the related HSs. For free L, H…H and O…H/H…O contacts (red spots
on the HS) contribute considerably to the crystal cohesion. (ii) Full fingerprint of L has a
symmetric shape, while the full fingerprints of two symmetry-independent molecules of 1 have a
nearly symmetric shape. In 2, the FP has an asymmetric shape as a consequence of the presence
of three components in the structure. (iii) A visual evaluation of HSs and FPs simply elucidates a
more efficient packing in 2 afforded by the presence of the strong hydrogen bond interactions O–
H…O and O–H…Cl in the crystal lattice, where such strong interactions are absent in 1. (iv) The
complexation of L with SnIV in 1 results in reduction of O…H/H…O contacts, due to the
involvement of P═O in the Sn―O═P bond and so its non-availability as a H-bond acceptor.
Conversely, for 2, the coordination of L to MnII leads to reduction and increase, respectively, for
H…H and O…H/H…O contacts.
Finally, comparison of HSs and FPs of organotin(IV)-phosphoric triamide complex 1
with previously reported analogues, which include only four complexes, reveals that the
dominant interactions were the H…H and Cl…H/H…Cl contacts (associated to the N–H…Cl or
C–H…Cl hydrogen bonds). The involvement of chloride is due to Sn(CH3)2Cl2 present in the
organotin(IV)-phosphoric triamides studied. Additionally, the NH units in the PT ligands, as
good H-bond donors, affect the contacts which are predominantly involved in crystal packing.
Supplementary data
CCDC 943564 (1) and 943565 (2) for the reported complexes contain the supplementary
crystallographic data for this paper. These data can be obtained free of charge from the
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
12

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14

Figure captions
Figure 1. The asymmetric unit of 1, showing two independent molecules Sn1 and Sn1' and the
atom-labelling scheme for non-C atoms. Displacement ellipsoids are given at 50% probability
and hydrogens are drawn as small spheres of arbitrary radii. Disordered oxygens of the major
and minor components are labeled as suffixes "prime" and "capital letter A", respectively, and
other disordered atoms are not labeled for clarity.
Figure 2. The structure of [Mn(H2O)4(trans-OP[NC4H8O]3)2]Cl2·2H2O (2), showing the atom-
labelling scheme for non-C atoms. Displacement ellipsoids are given at 50% probability and
hydrogens are drawn as small spheres of arbitrary radii.
Figure 3. Polyhedron view of 1 in the unit cell. Color codes of atoms are: dark green (Sn), light
green (Cl), purple (P), red (O), dark grey (C), light grey (H) and blue (N).
Figure 4. Polyhedron view of 2 in the unit cell. Color codes of atoms are: dark green (Mn), light
green (Cl), purple (P), red (O), dark grey (C), light grey (H) and blue (N).
Figure 5. Top: Views of crystal packing of 2, showing a 2D layer generated by O‒ H…O and
OH…Cl hydrogen bonds (dashed lines, table 4) parallel with the ab plane. The MnII centers and
bonds attached to them are highlighted as "ball and stick". Lower: View of O‒ H…O and
OH…Cl hydrogen bonds (dashed lines) between the complex dication, Cl– and H2O
components of 2.
Figure 6. Top: A view of dnorm HS for L, surrounded by neighboring molecules associated with
close contacts O…H/H…O (black dashed lines) and H…H (orange dashed lines); Lower:
Decomposed H…H and O…H/H…O FPs and related percentage contributions to the total HS
area for L. The full FP appears as a grey shadow below each decomposed plot.
Figure 7. Top: Views of dnorm HS for molecule Sn1 of 1, in two orientations, surrounded by
neighboring molecules associated with close contacts O…H/H…O (identified as red spots) and
H…H (orange dashed circles); Lower: Decomposed H…H and O…H/H…O FPs and related
percentage contributions to the total HS area for Sn1 of 1. Very short spike on O…H/H…O FP is
highlighted by a red circle. The full FP (with values of 1.0 Å < de, di < 2.7 Å) appears as a grey
shadow below each decomposed plot.
Figure 8. Top: Views of dnorm HS for Sn1 of 1, in two orientations, surrounded by neighboring
molecules associated with close contacts Cl…H/H…Cl (black dashed lines); Lower:
Decomposed Cl…H/H…Cl FP and related percentage contribution to the total HS area for Sn1
of 1.
Figure 9. Top: Views of dnorm HS for Sn1' of 1, in two orientations, surrounded by neighboring
molecules associated with close contacts O…H/H…O (identified as red spots) and H…H
(orange dashed circles). The combined C…C and H…H contacts are marked by a red arrow;
Lower: Decomposed H…H and O…H/H…O FPs and related percentage contributions to the
15

total HS area for Sn1' of 1. The full FP (with values of 1.0 Å < de, di < 2.7 Å) appears as a grey
shadow below each decomposed plot.
Figure 10. Top: Views of dnorm HS for Sn1' of 1, in two orientations, surrounded by neighboring
molecules associated with close contacts Cl…H/H…Cl (black dashed lines); Lower:
Decomposed Cl…H/H…Cl FP and related percentage contribution to the total HS area for Sn1'
of 1.
Figure 11. Top: A view of dnorm HS for 2, surrounded by neighboring components associated
with close contacts O…H/H…O (black dashed lines) and H…Cl (orange dashed lines); Lower:
Decomposed H…H, O…H/H…O and H…Cl FPs and related percentage contributions to the
total HS area for 2. A red dashed circle on decomposed O…H/H…O FP highlight the very short
thin spike. The full FP (with values of 0.9 Å < de < 2.5 Å and 0.7 Å < di < 2.4 Å) appears as a
grey shadow below each decomposed plot.
16

Table 1. Crystal data and structure refinement for 1 and 2.
1
2
CCDC number
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
943564
943565
C26H54Cl2N6O8P2Sn
830.28
C24H60Cl2N6O14P2Mn
844.56
100(2)
200(2)
0.71073
0.71073
Monoclinic
P21/c
Triclinic
Space group
P
Unit cell dimensions
a = 16.1409(16) Å
b = 15.2677(15) Å
c = 29.441(3) Å
a = 8.6360(5) Å
b = 9.1771(5) Å
c = 14.0202(8) Å
α = 85.258(3)°
β = 78.430(2)°
γ = 63.125(2)°
970.96(10)
1
β = 91.794(4)°
Volume (Å3)
7251.7(13)
8
Z
Density (calculated) (g/cm3)
Absorption coefficient (mm–1)
F(000)
1.521
1.444
0.992
0.626
3440
447
Crystal size (mm3)
Crystal color / habit
Theta range for data collection (°)
Index ranges
0.23 × 0.20 × 0.10
Colorless / flake
1.38 to 31.53
0.24 × 0.11 × 0.07
Colorless / blade
2.49 to 27.24
–23 ≤ h ≤ 19
–22 ≤ k ≤ 21
–42 ≤ l ≤ 43
–8 ≤ h ≤ 11
–11 ≤ k ≤ 11
–18 ≤ l ≤ 18
Reflections collected
103240
24205
Independent reflections
Completeness to theta = 25.00°
Absorption correction
22023 [Rint = 0.0416]
99.9%
4304 [Rint = 0.0281]
99.6%
Multi-scan / sadabs
0.9073 and 0.8039
Full-matrix least-squares on F2
22023 / 55 / 819
1.009
Multi-scan / sadabs
0.9575 and 0.8642
Full-matrix least-squares on F2
4304 / 6 / 247
Max. and min. transmission
Refinement method
Data / restraints / parameters
Goodness-of-fit on F2
1.038
Final R indices [I>2σ(I)]
R indices (all data)
Largest diff. peak and hole (e.Å–3)
R1 = 0.0483, wR2 = 0.0935
R1 = 0.0960, wR2 = 0.1138
1.543 and –1.639
R1 = 0.0412, wR2 = 0.1096
R1 = 0.0476, wR2 = 0.1141
1.482 and –1.316
17

Table 2. The H…X distances [Å] for highlighted interactions in L, 1 and 2.
L
C12‒ H12...O2i
C1‒ H13...O3'ii
2.466
2.589
C5‒ H5...O3'ii
2.613
2.188
C5‒ H17...O4iv═P1 2.283
H11...H22iii
2.267
C10‒ H10...O3iii
1
C16‒ H16A...O2i
2.558
2.516
2.646
2.330
2.453
C18‒ H18B...O3iii 2.530
C13'‒ H13D...O6 2.330
C21'‒ H21C...O6iv 2.408
C23‒ H23B...Cl2'vi 3.011
C1‒ H1A...O2'ii
C6‒ H6A...O2'ii
C1'‒ H1'B...O5'
C12'‒ H12C...O5'
C11'…C11'
H11C...H11D
H18A...H2'B
H6B...H14D
3.023
2.177
2.227
2.276
C8‒ H8A...Cl1'v
2.927
C20‒ H20A...Cl2'v 2.968
i
C13‒ H13B...O3iii
2.482
2
O1‒ H1A...O1Wi
1.786
2.370
1.849
2.320
O3‒ H3Y...Cl1ii
O3‒ H3Y...Cl1
O3‒ H3Y...O2W
2.45
2.479
2.661
O3‒ H3Z...Cl2
O3‒ H3Z...Cl2iii
C7‒ H7A…O6vi
2.19
2.417
2.532
O1‒ H1A...Cl2i
O1‒ H1Y...O2W
O1‒ H1Y...Cl1
Symmetry transformations used to generate equivalent atoms for L: (i): x – 1, y, z; (ii): x + , –y +
, z + ; (iii): –x + 1, –y, –z + 1; (iv): –x + , y + , –z + ; for 1: (i): –x + 1, y – , –z + ; (ii): x, –y +
, z + ; (iii): –x + 1, –y, –z + 1; (iv): x, –y + , z – ; (v): –x + 1, –y + 1, –z + 1; (vi): –x, –y, –z + 1;
for 2: (i): x + 1, y, z; (ii): –x + 1, –y, –z; (iii): –x, –y + 1, –z; (iv): x + 1, y – 1, z.
18

Table 3. Selected bond distances (Å) and angles (°) for 1 and 2.
1
2
Sn1‒ C26
Sn1‒ C25
Sn1‒ O7
Sn1‒ O8
Sn1‒ Cl1
Sn1‒ Cl2
P1‒ O7
P1‒ N1
P1‒ N2
P1‒ N3
P2‒ O8
2.109(3)
2.120(3)
2.196(2)
2.204(2)
2.5579(10)
2.5613(10)
1.490(3)
1.632(3)
1.641(3)
1.644(3)
1.492(3)
1.642(3)
1.640(3)
1.644(3)
Sn1'‒ C26'
Sn1'‒ C25'
Sn1'‒ O7'
Sn1'‒ O8'
Sn1'‒ Cl2'
Sn1'‒ Cl1'
P1'‒ O7'
P1'‒ N2'
P1'‒ N1'
P1'‒ N3'
P2'‒ O8'
P2'‒ N5'
P2'‒ N6'
P2'‒ N4'
2.104(3)
2.111(3)
2.196(2)
2.201(2)
2.5499(10)
2.5518(10)
1.494(3)
1.556(5)
1.630(3)
1.689(4)
1.488(3)
1.596(4)
1.627(3)
1.665(3)
Mn1‒ O1i
Mn1‒ O2i
Mn1‒ O3i
P1‒ O2
P1‒ N1
P1‒ N2
2.1883(16)
2.1103(14)
2.1954(16)
1.4789(15)
1.6447(18)
1.6461(18)
1.6529(18)
P1‒ N3
P2‒ N5
P2‒ N4
P2‒ N6
O7‒ Sn1‒ O8
O7‒ Sn1‒ Cl1
O7‒ Sn1‒ Cl2
O8‒ Sn1‒ Cl1
O8‒ Sn1‒ Cl2
Cl1‒ Sn1‒ Cl2 179.59(3)
P1‒ O7‒ Sn1
P2‒ O8‒ Sn1
179.62(11)
90.99(7)
88.94(7)
88.67(7)
91.40(7)
O7'‒ Sn1'‒ O8'
179.62(12)
O1i‒ Mn1‒ O1 180.00(8)
O2i‒ Mn1‒ O1i 91.39(6)
O2‒ Mn1‒ O1i 88.61(6)
O2i‒ Mn1‒ O3i 91.84(6)
O2‒ Mn1‒ O3i 88.16(6)
O1i‒ Mn1‒ O3i 89.95(7)
O1‒ Mn1‒ O3i 90.05(7)
O7'‒ Sn1'‒ Cl2' 91.72(8)
O7'‒ Sn1'‒ Cl1' 88.20(8)
O8'‒ Sn1'‒ Cl2' 88.04(7)
O8'‒ Sn1'‒ Cl1' 92.04(7)
Cl2'‒ Sn1'‒ Cl1' 179.42(4)
150.94(15)
149.24(16)
P1'‒ O7'‒ Sn1'
P2'‒ O8'‒ Sn1'
152.72(17)
151.60(16)
P1‒ O2‒ Mn1
151.01(10)
Symmetry transformations used to generate equivalent atoms in 2: (i) –x+1, –y+1, –z.
19

Table 4. Hydrogen bonds for 2 [Å and °].
D‒ H...A
d(D‒ H)
d(H...A)
d(D...A)
(DHA)
O1‒ H1A...O1Wi
O1‒ H1A...Cl2i
O1‒ H1Y...O2W
O1‒ H1Y...Cl1
O3‒ H3Y...Cl1ii
O3‒ H3Y...Cl1
O3‒ H3Y...O2W
O3‒ H3Z...Cl2
O3‒ H3Z...Cl2iii
0.864(16)
0.864(16)
0.874(16)
0.874(16)
0.843(16)
0.843(16)
0.843(16)
0.861(16)
0.861(16)
1.786(17)
2.370(17)
1.849(19)
2.320(16)
2.45(2)
2.479(18)
2.661(19)
2.19(2)
2.641(5)
3.189(2)
2.699(5)
3.163(2)
3.104(2)
3.280(2)
3.399(5)
2.998(2)
3.156(2)
170(3)
158(2)
164(3)
162(3)
135(2)
159(3)
147(2)
156(2)
144(2)
2.417(19)
Symmetry transformations used to generate equivalent atoms: (i) x+1, y, z; (ii) –x+1, –y, –
z; (iii) –x, –y+1, –z.
20

Table 5. Summary of the percentage contributions of interactions for 1, I, II, III and IV.
H…H†
O...H/H…O
Cl…H/H…Cl
C…H/H…C
F…H/H…F
71.1
85.7
67.2
68.1
73.9
19.8 (red spot)
0.8
―
4.6 (red spot)
―
9.1
―
―
―
11.4
5.7
―
―
―
1
I‡
13.1 (red spot)
17.4 (red spot)
6.4 (red spot)
20.2 (red spot)
II
III
IV
9.3 (red spot)
―
*The formulas of complexes from literature are: ([C5H9NH]3PO)2SnCl2Me2 (I),
([(CH3)3CNH][C6H5CH2N(CH3)]2PO)SnCl2Me2 (II), ([3-F-C6H4C(O)NH][C6H11N(CH3)]2PO)2SnCl2Me2
(III) [5] and ([(4-CH3)C6H4NH][C5H9(4-CH3)N]2PO)SnCl2Me2 (IV) [20].
†Some H…H contacts appeared as light red spots on the related HSs.
‡Average values of three molecules of I are reported.
21

22

23

24

25

26

27

28

29