Article pubs.acs.org/IC
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
Mixed-Valent Cyanoplatinates Featuring Neptunyl−Neptunyl Cation−Cation Interactions Philip A. Smith,† Sarah M. Hickam,† Jennifer E. S. Szymanowski,† and Peter C. Burns*,†,‡ †
Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States ‡ Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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S Supporting Information *
ABSTRACT: The tetracyanoplatinate ligand was employed in synthesizing the first neptunyl cyanoplatinate complexes. Results indicate in situ oxidation of Pt(II) by Np(V/VI) to form mixed-valent Pt−Pt stacked columnar chains linked by cation−cation interaction induced chains of Np(V) polyhedra into a two-dimensional sheet structure. The Pt−Pt stacking distances of 3.04−3.05 Å are the longest reported columnar platinophilic interactions among mixed-valent tetracyanoplatinate structures. These complexes further illustrate the marked chemical differences and structural diversity of solidstate Np(V) coordination complexes with regard to Np(VI) and U(VI).
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sional platinophilic interactions.11,20 However, none of these reported compounds contain the stronger platinophilic interactions (1000 cps, and the instrument was operated in highvacuum mode. Samples were prepared by affixing crystalline material to a carbon tape mounting.
Table 2. Select Bond Distances for 1 and 2 1
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RESULTS AND DISCUSSION Structural Description. Crystal Structure of Cs[NpO2(Pt(CN)4)(H2O)1.80(OH)0.20]·H2O. The structure of 1 contains chains of neptunyl pentagonal bipyramids, in which the neptunyl ions are linked exclusively through CCIs, bridged by square-planar TCP to form an extended sheet that is parallel to (001) (Figure 1). The neptunyl (Np−Oyl) distances are
2
bond
distance (Å)
bond
distance (Å)
Np−O1 Np−O2 Np−O1′ Np−O4 Np−O5 Np−N1 Np−N3 Pt−Cavg CNavg Pt−Pt O4···N4 O4···O1 O4···O2 O3···O5 O3···N2 O3···N4 O5···O1
1.878(11) 1.810(10) 2.444(12) 2.547(11) 2.474(13) 2.523(14) 2.535(13) 2.007(17) 1.14(2) 3.0576(16) 2.96(2) 2.93(2) 3.67(2) 2.64(2) 3.54(2) 2.90(2) 3.22(2)
Np−O1 Np−O2 Np−O1′ Np−O3 Np−O4 Np−N1 Np−N3 Pt−Cavg CNavg Pt−Pt O3···O2 O3···N4 O4···O6w O4···N2 O4···O1 O5w···N4 O5w···N2 O6w···O2 O6w···O4 O6w···N2 O6w···O4′
1.876(7) 1.813(6) 2.437(8) 2.572(6) 2.478(8) 2.517(7) 2.498(7) 1.993(9) 1.157(11) 3.0393(11) 3.485(11) 2.984(11) 2.748(11) 2.913(11) 3.565(11) 3.202(11) 3.373(11) 3.222(11) 2.748(11) 3.002(11) 3.595(11)
Equatorial ligand O5 of the neptunyl polyhedron is best modeled as an oxygen with full occupancy; however, the significantly shorter Np−Oeq bond length in comparison with the O4 position (0.073(13) Å) and N-donor ligands (0.049− 0.0061(13) Å), along with the observation of a strong Hbonding interaction with interstitial O3 (D−A, 2.64 Å) suggests that the O5 position may possess a statistical mixture of H2O and OH−. Additionally, with O3 and Cs+ positions refining as fully occupied O and Cs+, an 80:20 H2O:OH− admixture of would be necessary to achieve overall charge balance. Interstitial water O3 may adopt two primary orientations, with both coordinating to Cs+ (3.138(12) Å). The first orientation may also accept a H-bond from O5 (as H2O) (Cs− O3−O5 angle 100°) and donates hydrogen bonds to N2 (D··· A = 3.54 Å) and N4 (2.90 Å), with an N2−O3−N4 angle of 98°. The second orientation donates H-bonds to N4 (2.90 Å) and O5 as hydroxyl (2.64 Åavg), with an angle of 102°. The neptunyl polyhedron equatorial ligand O5 likely forms a hydrogen-bonding interaction with -yl oxygen O1 (D···A = 3.22 Å) and, as previously mentioned, donates a H-bond to interstitial O3 (>2.64 Åavg) as H2O (O1−O5−O3 angle 100°). As hydroxyl, O5 would donate a H-bond to O1 and receive a H-bond from O3 (
