2.1 Pt(η⁴–P₄L) type

There are three complexes in which an inner coordination sphere about platinum atom is build up by organophosphines, their crystallographic and structural data are given in Table 1a. Most of the ligands presented here are open-chain podands and when including the metals macrocycles formed. In two complexes (Brüggeller and Hübner, 1990; Brüggeller et al., 1992) a ten-membered (P¹C₂P²C₂P³C₂P⁴) macrocycle forms three five-membered metallocyclic rings with the mean P–Pt–P bond angles of 84.3° (PC₂P).The mean Pt–P bond distances of 2.258(6) Å (Brüggeller and Hübner, 1990) and 2.274(5) Å (Brüggeller et al., 1992) for intra P² and P³ atoms are shorter than those for inter P¹ and P⁴ atoms of 2.327(5) Å (Brüggeller and Hübner, 1990; Brüggeller et al., 1992). These two complexes are diastereoisomers due to the chirality of the intra P atoms. The sum of four Pt–P bond distances of 9.17 Å and the value of Ʈ₄ parameter is 0.068 (Brüggeller and Hübner, 1990) in Brüggeller et al. (1992) the values are 9.20 Å and 0.075 these indicates that the inner coordination sphere of Pt(II) atom in Brüggeller and Hübner (1990) is somewhat more crowded than in Brüggeller et al. (1992) and less distorted than in its partner.

In triclinic [Pt{η⁴–C₂₂H₃₂P₄}]Br₂ (Mizuta et al., 1997) a 14-membered macrocycle creates a pairs of five- and six-member chelate rings in trans position about the central Pt(II) atom. The mean values of P–Pt–P bite angles are of 84.5° (PC₂P) and of 92.6° (PC₃P). The total mean value of Pt–P bond distances is 2.277(1) Å (Table 1a).

2.2 Pt(η⁴–P₃SiL) type

Monoclinic [Pt{η⁴–C₃₆H₅₄P₃Si}](C₃₂H₁₂B₁F₂₄) (Tsay et al., 2010) is only example of such type. Structure of [Pt{η⁴–C₃₆H₅₄P₃Si}]⁺ is shown in Figure 1 as can be seen the donor atoms build up a trigonal pyramidal geometry about Pt(II) atom (PtP₃Si). The trigonal plane is created by three P-donor atoms and Si atom completed the geometry. A 10-memered macrocycle forms three five-membered metallocylic rings (PC₂Si) with the mean value of P–Pt–Si chelate rings of 85.3° (Table 1b). The mean value of P–Pt–P bond angles is 119.3°. The mean value of Pt–P bond distances is 2.373 Å and Pt–Si bond distance is 2.259 Å.

Figure 1

Structure of [Pt{η⁴–C₃₆H₅₄P₃Si}]⁺ (Tsay et al., 2010).

2.3 Pt(η⁴–P₂N₂L) type

There are six cis-derivatives of this type and their structural data are gathered in Table 1c. Structure of monoclinic cis-[Pt(η⁴–C₅₂H₃₈N₄P₂)] (Elsegood et al., 2009) is shown in Figure 2 as an example. As can be seen 10-membered macrocycle (P¹C=NN¹C₂N²N=CP²) forms three five-membered metallocyclic rings with the central N¹C₂N² ring and two satellites P¹C=NN¹/N²N=CP² rings.

Figure 2

Structure of cis-[Pt(η⁴–C₅₂H₃₈N₄P₂)] (Elsegood et al., 2009).

The value of N¹–Pt–N² bite angle is 81.7° and the values of satellites rings P¹–Pt–N¹ 83.5° and N²–Pt–P² in 82.7°, respectively. The mean values of Pt–P and Pt–N bond distances are 2.239 and 2.007 Å, respectively.

In another four cis-complexes: monoclinic [Pt(η⁴–C₄₄H₃₂N₂O₂P₂)]·CHCl₃ (Burger et al., 2003), orthorhombic [Pt(η⁴–C₄₄H₃₈N₂O₂P₂)]], orthorhombic [Pt(η⁴–C₅₂H₄₀N₂O₂P₂)] · CH₂Cl₂ at 100 K), and monoclinic [Pt(η⁴–C₅₂H₄₂N₂O₂P₂)] · CH₂Cl₂ (at 173 K) (Swanson et al., 2011) the respective 12-membered macrocycle creates central five-membered ring N¹–C₂–N² with two sixmembered satellites rings (P¹C₃N¹/N²C₃P²). The mean values of L–Pt–L chelate angles open in the order 81.6° (N¹–Pt–N²) < 86.8° (P¹–Pt–N²) < 89.6° (N²–Pt–P²). The mean values of Pt–L bond distances are 2.238 Å (L=P) and 2.062 Å (L=N), respectively (Table 1c).

In monoclinic cis-[Pt(η⁴–C₃₄H₄₀N₈O₂P₂)](ClO₄)₂·Me₂CO (Miller et al., 2009) a 12-membered macrocycle forms central five-membered ring (P¹C₂P²) with two six-membered satellites rings (N¹CNCP¹/P²CNCN²), with the values of the L–Pt–L chelate angles of 88.2° (P¹–Pt–P²), 85.6° (N¹–Pt–P¹), and 86.8° (P²–Pt–N²). The mean values of Pt–L bond distances are 2.188 Å (L=P) and 2.125 Å (L=N), respectively.

2.4 Pt(η⁴–P₂S₂L) type

There are two complexes with cis-configuration and two with trans-configuration of such type (Table 1d). In triclinic cis-[Pt(η⁴–C₃₀H₃₂P₂S₂)](PF₆)₂·Me₂CN) (Connolly et al., 1997) a 10-membered macrocycle creates three five-membered rings, central (S¹C₂S²), with two satellites (P¹C₂S¹/S²C₂P²), with the values of the L–Pt–L chelate angles of 84.5° (S¹–Pt–S²), 85.3° (P¹–Pt–S¹) and 87.1° (S²–Pt–P²). The mean values of Pt–L bond distances are 2.263 Å (L=P) and 2.343 Å (L=S), respectively.

In monoclinic cis-[Pt(η⁴–C₂₂H₃₀P₂S₂)](PF₆)₂·MeNO₂ (Champness et al., 1994) a 14-membered macrocycle ligand coordinates to the Pt(II) atom via two thioether and two phosphine donor groups (Figure 3). As can be seen the geometry is distorted square-planar with the phenyl groups oriented to one side of the coordination plane and the methylene group directed to the other side. The Pt(II) atom displaced above the least squares P₂S₂ plane towards the phenyl groups by 0.12 Å, indicating a poor match between the metal atom radius and the macrocycling created cavity. A 14-remembered macrocycle creates a pairs of five-(P¹C₂S²/P²C₂S¹) and six-(P¹C₃P²/S¹C₃S²) membered chelate rings in trans-position about the central Pt(II) atom. The values of L–Pt–L chelate angles are 88.1° (mean) (P–Pt–S), 94.2° (P–Pt–P), and 89.0° (S–Pt–S). The mean values of Pt–L bond distances are 2.250 Å (L=P) and 2.341 Å (L=S), respectively.

Figure 3

Structure of cis-[Pt(η⁴–C₂₂H₃₀P₂S₂)] (Champness et al., 1994).

In monoclinic trans-[Pt(η⁴–C₃₀H₃₀P₂S₂)](PF₆)₂·C₆H₆ (Kyba et al., 1985) a 14-membered macrocycle creates a pair of five-(S¹C₂P²/S²C₂P¹) and six-(P¹C₃S¹/P²C₃S²)-membered chelate rings (Figure 4). The mean values of L–Pt–L bite angles are 87.5° (P–Pt–S) for five- and 92.6° (P–Pt–S) for six-membered rings. The mean value of Pt–L bond distances is 2.295 Å (L=P) and 2.292 Å (L=S), respectively.

Figure 4

Structure of trans-[Pt(η⁴–C₃₀H₃₀P₂S₂)] (Kyba et al., 1985).

In triclinic trans-[Pt(η⁴–C₂₄H₃₄P₂S₂)](Cl)₂·CH₂Cl₂ (Toto et al., 1990) a 16-membered macrocycle creates four sixmembered chelate rings (P¹C₃S¹/P¹C₃S²) and (P²C₃S¹/P²C₃S²), with the mean values of the P–Pt–S bite angles of 83.3° (P¹–Pt–S^1,2) and 96.7° (P²–Pt–S^1,2). The mean values of Pt–L bond distances are 2.315 Å (L=P) and 2.315 Å (L=S), respectively.

2.5 Pt(η⁴–P₂C₂L) type

Triclinic trans-[Pt(η⁴–C₂₆H₃₄N₄P₂)](PF₆)₂·MeCN (Flores-Figueroa et al., 2010) is only example of such type. A 16-membered macrocycle creates four six-(P¹C₂NC¹NC₂P²C₂NC²NC₂) membered chelate rings build up an “ideal” square-planar geometry about Pt(II) atom, with the values of cis P–Pt–C bond angles of 90.0° and trans P–Pt–P and C–Pt–C of 180.0° (Table 1e). The mean values of Pt–L bond distances are 2.300 Å (L=P) and 2.023 Å (L=C), respectively (Table 1e).

2.6 Pt(η⁴–PN₃L) type

There are two complexes triclinic anti– and monoclinic syn-[Pt(η⁴–C₃₅H₂₈N₃O₃P)] (Durran et al., 2007) with such type (Table 1f). Structure of syn-complex is shown in Figure 5. As can be seen in each the 11-membered macrocycle forms one six-(P¹C₃N¹), and two five-membered (N¹C₂N², N²C₂N³) chelate rings. Structural parameter is very similar (Table 1f). These two complexes are differing from each other by crystal class, as well as by Pt–L bond distances and L–Pt–L bond angles. The sum of four (Pt–P_(1x)–N_(3x)) bond distances of 8.247 Å and the value of parameter Ʈ₄ 0.052 (anti-complex); and in (syn-complex) the values are 8.264 Å and 0.061. These indicates that the inner coordination sphere about central platinum atom in anti-complex is somewhat more crowded and less distorted than its anti-partner.

Figure 5

Structure of syn-[Pt(η⁴–C₃₅H₂₈N₃O₃P)] (Durran et al., 2007).

2.7 Pt(η⁴–PN₂OL) type

There are three examples of such type, and their structural data are gathered in Table 1g. In two triclinic cis-[Pt(η⁴–C₂₈H₂₃N₄O₂P)]·0.5Et₂O (Elsegood et al., 2011) and [Pt(η⁴–C₂₇H₂₁N₂O₂P)]·MeOH (Durran et al., 2010) each 11-membered macrocycle creates one six-(P¹C₃N¹) and two five-(N¹C₂N²/N²C₂O¹)-membered chelate rings. Structural data are well comparable (Table 1g).

Structure of orthorhombic cis-[Pt(η⁴–C₂₉H₂₅N₂O₂P)] (Durran et al., 2010) is shown in Figure 6. As can be seen 12-membered macrocycle creates three chelate rings, namely (P¹C₃N¹C₂N²C₃O¹) central five-(N¹C₂N²) and two satellites six-(P¹C₃N¹/N²C₃O¹) members. The values of L–Pt–L chelate angles are: 93.7°(P¹–Pt–N¹), 83.4° (N¹–Pt–N²), and 93.6° (N²–Pt–O¹). The Pt–L bond distances elongate in the order 1.973 Å (Pt–N¹) < 1.974 Å (Pt–O¹) < 2.005 Å (Pt–N²) < 2.219 Å (Pt–P).

Figure 6

Structure of cis-[Pt(η⁴–C₂₉H₂₅N₂O₂P)] (Durran et al., 2010).