Tris(3,5-di­aza-1-azonia-7-phosphaadamant-7-yl)(1,3,5-tri­aza-7-phospha-adamantane)silver(I) dicarbonate

Zamisa, S.J.; Adeleke, A.A.; Olatunji, O.S.; Omondi, B.

doi:10.1107/S2414314626007935

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 11| Part 8| August 2026| x260793

https://doi.org/10.1107/S2414314626007935

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Tris(3,5-diaza-1-azonia-7-phosphaadamant-7-yl)(1,3,5-triaza-7-phospha-adamantane)silver(I) dicarbonate

Sizwe J. Zamisa,^a ^* Adesola A. Adeleke,^a Olatunde S. Olatunji ^a and Bernard Omondi ^a

^aSchool of Agriculture and Science, Discipline of Chemistry, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa
^*Correspondence e-mail: [email protected]

Edited by W. T. A. Harrison, University of Aberdeen, United Kingdom (Received 29 July 2026; accepted 3 August 2026; online 14 August 2026)

The title compound, [Ag(C₆H₁₃N₃P)₄(C₆H₁₂N₃P)](CO₃)₂ or [Ag(PTAH)₃(PTA)](CO₃)₂, is a discrete cationic silver(I) complex composed of one neutral 1,3,5-triaza-7-phosphaadamantane (C₆H₁₂N₃P; PTA) ligand and three monoprotonated PTAH⁺ (C₆H₁₃N₃P⁺) ligands coordinated to the silver center, resulting in an overall +4 charge balanced by two carbonate anions. The compound crystallizes in the rhombohedral R3 space group with the silver ion and PTA P atom lying on a crystallographic threefold axis, as does one of the carbonate C atoms. The silver ion adopts a tetrahedral geometry with P—Ag—P bond angles near the ideal 109°, and silver–phosphorus bond distances of 2.4699 (6) and 2.4683 (11) Å for Ag—P_PTA and Ag—P_PTAH, respectively. The crystal packing features N—H⋯O hydrogen bonds between the protonated N atoms of the PTAH ligands and the non-coordinating carbonate anions.

Keywords: crystal structure; neutral 1,3,5-triaza-7-phosphaadamantane (PTA); monoprotonated PTAH; carbonate ion; silver ion.

CCDC reference: 2578472

Structure description

The phosphine ligand 1,3,5-triaza-7-phosphaadamantane (C₆H₁₂N₃P; PTA) has garnered growing interest because of its water solubility and distinctive coordination properties arising from a soft phosphorus donor and three nitrogen atoms (Krogstad et al., 2007 ). While PTA mainly binds to metals via the phosphorus atom, its nitrogen atoms can enable diverse coordination modes, impacting complex stability and functionality (Darensbourg et al., 1997 ). Silver(I) complexes with PTA display enhanced solubility and stability useful in catalysis and biomedical fields (Jimenez et al., 2017 ; Armstrong et al., 2018 ).

As part of our studies in this area, this work reports the synthesis and crystal structure of the title salt [Ag(PTAH)₃(PTA)](CO₃)₂ (I), illustrating the coordination of silver(I) with both neutral PTA and protonated PTAH ligands in the presence of carbonate counter-ions.

The asymmetric unit of (I) consists of an Ag ion (site symmetry 3), a complete PTAH ligand, a fragment of PTA (P site symmetry 3), a complete carbonate anion and a fragment of a carbonate ion (C site symmetry 3), as shown in Fig. 1. The complete cation is constructed through symmetry code 1 − y, x − y, z, which results in the silver atom coordinated with one neutral PTA and three monoprotonated PTA ligands, forming a cationic complex with a +4 charge balanced by two carbonate anions. The Ag center again exhibits tetrahedral geometry, with bond angles averaging close to the ideal tetrahedral angle of 109°. The Ag—P1 and Ag—P2 bond distances are 2.4699 (6) and 2.4683 (11) Å, respectively. The P—Ag—P bond angles are comparable to those of other tetra-coordinated metal phosphine complexes such as [Cu(PTA)₄][BF₄]·6H₂O and [Cu(PTAH)₄][NO₃]₅ with an average P—Cu—P bond angle of 109.5° (Kirillov et al., 2007 , Porchia et al., 2009 ). In the extended structure of (I), the carbonate ions accept strong N—H⋯O hydrogen bonds arising from the protonated nitrogen atoms of the HPTA ligands (Fig. 2). These hydrogen bonds are characterized by an N⋯O distance of 2.731 (3) Å and an N—H⋯O angle of 176°, indicating strong and directional intermolecular interactions (Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O6ⁱ	1.00	1.73	2.731 (3)	176
Symmetry code: (i) $[-x+y+{\script{1\over 3}}, -x+{\script{2\over 3}}, z-{\script{1\over 3}}]$ .

Figure 1
The molecular structure of (I) shown with displacement ellipsoids at the 50% probability level. All C-bound hydrogen atoms are omitted for clarity. Symmetry codes: (i) 1 − y, x − y, z; (ii) 1 + y − x, 1 − x, z.

Figure 2
Representation of N—H⋯O hydrogen bonds in the crystal structure of (I) (blue and red dotted bonds).

Synthesis and crystallization

Formic acid (0.3 ml, 8.0 mmol) was added slowly to silver(I) oxide (0.93 g, 4.0 mmol) in water (10 ml), generating silver(I) formate, which was filtered to remove unreacted material. PTA (1.26 g, 8.0 mmol) dissolved in acetone (20 ml) was added dropwise to the filtrate, yielding a cloudy solution. Slow evaporation of the filtered solution afforded X-ray quality crystals of (I) suitable for analysis. The carbonate ions in the product may have arisen from CO₂ absorbed from the atmosphere in the presence of silver ions (Barnes et al., 1971 ; Kong et al., 2005 ).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	[Ag(C₆H₁₃N₃P)₄(C₆H₁₂N₃P)](CO₃)₂
M_r	859.52
Crystal system, space group	Trigonal, R3
Temperature (K)	173
a, c (Å)	15.7992 (12), 13.1502 (18)
V (Å³)	2842.7 (6)
Z	3
Radiation type	Mo Kα
μ (mm⁻¹)	0.78
Crystal size (mm)	0.36 × 0.24 × 0.22

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.767, 0.847
No. of measured, independent and observed [I > 2σ(I)] reflections	18709, 3005, 2981
R_int	0.022
(sin θ/λ)_max (Å⁻¹)	0.668

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.048, 1.08
No. of reflections	3005
No. of parameters	172
No. of restraints	13
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.77, −0.32
Absolute structure	Flack x determined using 1393 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 )
Absolute structure parameter	−0.013 (5)
Computer programs: APEX2 and SAINT (Bruker, 2014 ), SHELXS97 (Sheldrick, 2008 ), SHELXL2018/3 (Sheldrick, 2015 ) and OLEX2 (Dolomanov et al., 2009 ).

Structural data

CCDC reference: 2578472

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314626007935/hb4568sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314626007935/hb4568Isup2.hkl

checkCIF report

Computing details top

(I) top

Crystal data top

[Ag(C₆H₁₃N₃P)₄(C₆H₁₂N₃P)](CO₃)₂	D_x = 1.506 Mg m⁻³
M_r = 859.52	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 9969 reflections
a = 15.7992 (12) Å	θ = 2.6–28.3°
c = 13.1502 (18) Å	µ = 0.78 mm⁻¹
V = 2842.7 (6) Å³	T = 173 K
Z = 3	Block, colourless
F(000) = 1518	0.36 × 0.24 × 0.22 mm

Data collection top

Bruker APEXII CCD diffractometer	2981 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.022
φ and ω scans	θ_max = 28.3°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −21→17
T_min = 0.767, T_max = 0.847	k = −15→21
18709 measured reflections	l = −17→17
3005 independent reflections

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.019	w = 1/[σ²(F_o²) + (0.031P)² + 1.7576P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.048	(Δ/σ)_max = 0.001
S = 1.08	Δρ_max = 0.77 e Å⁻³
3005 reflections	Δρ_min = −0.32 e Å⁻³
172 parameters	Absolute structure: Flack x determined using 1393 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013)
13 restraints	Absolute structure parameter: −0.013 (5)
Primary atom site location: dual

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2sigma(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C7	0.54971 (19)	0.2863 (2)	0.48563 (19)	0.0157 (5)
H7A	0.518427	0.324777	0.465991	0.019*
H7B	0.505181	0.217503	0.465855	0.019*
C8	0.5965 (2)	0.6287 (2)	0.1338 (2)	0.0154 (5)
H8A	0.657144	0.668832	0.173223	0.018*
H8B	0.573099	0.672593	0.108986	0.018*
C9	0.6073 (2)	0.2336 (2)	0.6302 (2)	0.0157 (5)
H9A	0.605558	0.230630	0.705424	0.019*
H9B	0.567006	0.166064	0.604429	0.019*
N6	0.56354 (17)	0.29178 (17)	0.59648 (17)	0.0146 (4)
C1	0.55921 (19)	0.4978 (2)	0.25461 (19)	0.0134 (5)
H1A	0.508041	0.450520	0.301041	0.016*
H1B	0.616570	0.542448	0.296270	0.016*
C2	0.48116 (19)	0.37213 (18)	0.08897 (18)	0.0128 (5)
H2A	0.490640	0.340303	0.028633	0.015*
H2B	0.427627	0.320959	0.130269	0.015*
C3	0.66953 (18)	0.53329 (18)	0.07806 (18)	0.0114 (5)
H3A	0.731342	0.579620	0.112530	0.014*
H3B	0.686222	0.507770	0.017146	0.014*
C4	0.53229 (19)	0.5242 (2)	−0.01127 (19)	0.0136 (5)
H4A	0.548519	0.492784	−0.067233	0.016*
H4B	0.507300	0.564661	−0.041889	0.016*
C5	0.4345 (2)	0.4943 (2)	0.14521 (19)	0.0149 (5)
H5A	0.406948	0.534767	0.120457	0.018*
H5B	0.385635	0.443460	0.190774	0.018*
N1	0.52210 (16)	0.55474 (17)	0.20140 (16)	0.0134 (4)
N2	0.45315 (15)	0.44554 (16)	0.05507 (16)	0.0120 (4)
H2	0.391704	0.410798	0.014182	0.014*
N3	0.61909 (16)	0.58570 (16)	0.04598 (16)	0.0124 (4)
P1	0.59476 (5)	0.43083 (5)	0.16489 (5)	0.01082 (13)
P2	0.666667	0.333333	0.41562 (8)	0.0119 (2)
Ag1	0.666667	0.333333	0.22792 (2)	0.00986 (8)
C6	0.34261 (19)	0.22240 (19)	0.32803 (19)	0.0118 (5)
O3	0.3890 (2)	0.1866 (2)	0.28981 (18)	0.0361 (6)
O6	0.32156 (19)	0.27601 (18)	0.27414 (18)	0.0295 (5)
O7	0.31591 (19)	0.2064 (2)	0.41785 (18)	0.0316 (5)
C10	0.666667	0.333333	0.8982 (3)	0.0112 (7)
O2	0.60792 (17)	0.36433 (18)	0.89697 (18)	0.0279 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C7	0.0127 (12)	0.0189 (13)	0.0139 (11)	0.0068 (11)	0.0001 (9)	0.0023 (10)
C8	0.0170 (13)	0.0140 (12)	0.0176 (12)	0.0096 (11)	−0.0013 (10)	−0.0017 (10)
C9	0.0171 (13)	0.0143 (12)	0.0137 (11)	0.0064 (10)	0.0015 (9)	0.0028 (9)
N6	0.0129 (11)	0.0176 (12)	0.0127 (10)	0.0071 (9)	0.0005 (8)	−0.0002 (9)
C1	0.0140 (12)	0.0174 (13)	0.0110 (10)	0.0096 (10)	−0.0006 (9)	−0.0007 (9)
C2	0.0131 (12)	0.0124 (12)	0.0136 (11)	0.0068 (10)	0.0005 (9)	−0.0007 (9)
C3	0.0092 (11)	0.0126 (11)	0.0136 (10)	0.0063 (10)	0.0004 (9)	0.0023 (9)
C4	0.0151 (12)	0.0156 (12)	0.0113 (10)	0.0086 (10)	0.0003 (9)	0.0011 (10)
C5	0.0145 (12)	0.0190 (13)	0.0144 (11)	0.0108 (11)	−0.0003 (9)	−0.0046 (9)
N1	0.0132 (10)	0.0153 (11)	0.0147 (10)	0.0094 (9)	−0.0015 (8)	−0.0021 (8)
N2	0.0111 (10)	0.0153 (11)	0.0112 (9)	0.0078 (9)	−0.0020 (8)	−0.0031 (8)
N3	0.0152 (10)	0.0109 (10)	0.0132 (9)	0.0081 (9)	0.0004 (8)	0.0013 (8)
P1	0.0116 (3)	0.0115 (3)	0.0113 (3)	0.0072 (3)	0.0004 (2)	0.0008 (2)
P2	0.0129 (3)	0.0129 (3)	0.0098 (4)	0.00647 (16)	0.000	0.000
Ag1	0.00977 (10)	0.00977 (10)	0.01003 (12)	0.00489 (5)	0.000	0.000
C6	0.0129 (11)	0.0140 (11)	0.0131 (10)	0.0102 (9)	0.0013 (8)	−0.0025 (8)
O3	0.0494 (14)	0.0499 (14)	0.0311 (11)	0.0413 (12)	0.0055 (10)	−0.0026 (10)
O6	0.0389 (14)	0.0341 (13)	0.0288 (12)	0.0283 (12)	0.0167 (10)	0.0141 (10)
O7	0.0349 (13)	0.0448 (15)	0.0234 (11)	0.0260 (12)	0.0044 (10)	0.0044 (10)
C10	0.0140 (11)	0.0140 (11)	0.0055 (15)	0.0070 (5)	0.000	0.000
O2	0.0252 (11)	0.0325 (12)	0.0327 (12)	0.0194 (10)	−0.0028 (9)	−0.0079 (9)

Geometric parameters (Å, º) top

C7—H7A	0.9900	C3—H3B	0.9900
C7—H7B	0.9900	C3—N3	1.469 (3)
C7—N6	1.470 (3)	C3—P1	1.846 (3)
C7—P2	1.855 (3)	C4—H4A	0.9900
C8—H8A	0.9900	C4—H4B	0.9900
C8—H8B	0.9900	C4—N2	1.521 (3)
C8—N1	1.471 (3)	C4—N3	1.435 (3)
C8—N3	1.472 (3)	C5—H5A	0.9900
C9—H9A	0.9900	C5—H5B	0.9900
C9—H9B	0.9900	C5—N1	1.433 (3)
C9—N6ⁱ	1.463 (4)	C5—N2	1.521 (3)
C9—N6	1.468 (4)	N2—H2	1.0000
C1—H1A	0.9900	P1—Ag1	2.4699 (6)
C1—H1B	0.9900	P2—Ag1	2.4683 (11)
C1—N1	1.473 (3)	C6—O3	1.235 (3)
C1—P1	1.849 (3)	C6—O6	1.269 (3)
C2—H2A	0.9900	C6—O7	1.237 (3)
C2—H2B	0.9900	C10—O2ⁱⁱ	1.247 (2)
C2—N2	1.501 (3)	C10—O2	1.247 (2)
C2—P1	1.848 (3)	C10—O2ⁱ	1.247 (2)
C3—H3A	0.9900

H7A—C7—H7B	107.9	N3—C4—N2	111.7 (2)
N6—C7—H7A	109.1	H5A—C5—H5B	107.9
N6—C7—H7B	109.1	N1—C5—H5A	109.3
N6—C7—P2	112.30 (18)	N1—C5—H5B	109.3
P2—C7—H7A	109.1	N1—C5—N2	111.8 (2)
P2—C7—H7B	109.1	N2—C5—H5A	109.3
H8A—C8—H8B	107.8	N2—C5—H5B	109.3
N1—C8—H8A	109.0	C8—N1—C1	111.6 (2)
N1—C8—H8B	109.0	C5—N1—C8	109.9 (2)
N1—C8—N3	112.9 (2)	C5—N1—C1	112.7 (2)
N3—C8—H8A	109.0	C2—N2—C4	111.21 (19)
N3—C8—H8B	109.0	C2—N2—C5	111.54 (19)
H9A—C9—H9B	107.6	C2—N2—H2	108.4
N6—C9—H9A	108.7	C4—N2—C5	108.8 (2)
N6ⁱ—C9—H9A	108.7	C4—N2—H2	108.4
N6ⁱ—C9—H9B	108.7	C5—N2—H2	108.4
N6—C9—H9B	108.7	C3—N3—C8	111.1 (2)
N6ⁱ—C9—N6	114.1 (2)	C4—N3—C8	110.8 (2)
C9ⁱⁱ—N6—C7	111.4 (2)	C4—N3—C3	111.9 (2)
C9—N6—C7	111.4 (2)	C1—P1—Ag1	120.57 (8)
C9ⁱⁱ—N6—C9	108.4 (2)	C2—P1—C1	97.77 (12)
H1A—C1—H1B	107.9	C2—P1—Ag1	120.17 (8)
N1—C1—H1A	109.2	C3—P1—C1	97.89 (12)
N1—C1—H1B	109.2	C3—P1—C2	98.11 (11)
N1—C1—P1	111.95 (16)	C3—P1—Ag1	117.54 (8)
P1—C1—H1A	109.2	C7ⁱ—P2—C7	97.50 (11)
P1—C1—H1B	109.2	C7ⁱ—P2—C7ⁱⁱ	97.50 (11)
H2A—C2—H2B	108.0	C7ⁱⁱ—P2—C7	97.50 (11)
N2—C2—H2A	109.4	C7ⁱⁱ—P2—Ag1	119.75 (8)
N2—C2—H2B	109.4	C7ⁱ—P2—Ag1	119.75 (8)
N2—C2—P1	111.12 (17)	C7—P2—Ag1	119.75 (8)
P1—C2—H2A	109.4	P1ⁱ—Ag1—P1	109.333 (15)
P1—C2—H2B	109.4	P1ⁱⁱ—Ag1—P1	109.332 (15)
H3A—C3—H3B	107.8	P1ⁱⁱ—Ag1—P1ⁱ	109.337 (15)
N3—C3—H3A	109.1	P2—Ag1—P1ⁱⁱ	109.608 (15)
N3—C3—H3B	109.1	P2—Ag1—P1	109.608 (15)
N3—C3—P1	112.47 (17)	P2—Ag1—P1ⁱ	109.608 (15)
P1—C3—H3A	109.1	O3—C6—O6	119.5 (2)
P1—C3—H3B	109.1	O3—C6—O7	121.0 (3)
H4A—C4—H4B	107.9	O7—C6—O6	119.5 (2)
N2—C4—H4A	109.3	O2ⁱ—C10—O2	119.982 (11)
N2—C4—H4B	109.3	O2ⁱ—C10—O2ⁱⁱ	119.983 (11)
N3—C4—H4A	109.3	O2ⁱⁱ—C10—O2	119.984 (11)
N3—C4—H4B	109.3

N6—C7—P2—C7ⁱ	49.24 (17)	N2—C5—N1—C8	57.1 (3)
N6—C7—P2—C7ⁱⁱ	−49.39 (16)	N2—C5—N1—C1	−68.1 (3)
N6—C7—P2—Ag1	179.93 (15)	N3—C8—N1—C1	68.4 (3)
N6ⁱ—C9—N6—C7	67.4 (3)	N3—C8—N1—C5	−57.3 (3)
N6ⁱ—C9—N6—C9ⁱⁱ	−55.5 (3)	N3—C3—P1—C1	−49.28 (19)
N1—C8—N3—C3	−68.3 (3)	N3—C3—P1—C2	49.79 (19)
N1—C8—N3—C4	56.7 (3)	N3—C3—P1—Ag1	−179.92 (14)
N1—C1—P1—C2	−50.6 (2)	N3—C4—N2—C2	−68.5 (3)
N1—C1—P1—C3	48.8 (2)	N3—C4—N2—C5	54.7 (3)
N1—C1—P1—Ag1	177.40 (14)	P1—C1—N1—C8	−60.9 (2)
N1—C5—N2—C2	67.2 (3)	P1—C1—N1—C5	63.3 (2)
N1—C5—N2—C4	−55.8 (3)	P1—C2—N2—C4	60.7 (2)
N2—C2—P1—C1	50.14 (19)	P1—C2—N2—C5	−60.9 (2)
N2—C2—P1—C3	−49.03 (18)	P1—C3—N3—C8	61.3 (2)
N2—C2—P1—Ag1	−177.56 (12)	P1—C3—N3—C4	−63.1 (2)
N2—C4—N3—C8	−55.4 (3)	P2—C7—N6—C9ⁱⁱ	60.8 (3)
N2—C4—N3—C3	69.2 (3)	P2—C7—N6—C9	−60.4 (3)

Symmetry codes: (i) −y+1, x−y, z; (ii) −x+y+1, −x+1, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O6ⁱⁱⁱ	1.00	1.73	2.731 (3)	176

Symmetry code: (iii) −x+y+1/3, −x+2/3, z−1/3.

Acknowledgements

We thank the University of KwaZulu-Natal for its support of this research.

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