Organodiphosphines in cis-Pt(η²-PX_nP)(Cl)₂ (n = 1,2,3) derivatives: Structural aspects

Abbreviations

(C₅H₁₀N)₂P(C₅H₈)P(C₅H₁₀N)₂

1,2-bis(bis(piperidin-1-yl)phosphino)cyclopentane

(C₆H₂Bu ^t ₃)P(C₁₆H₁₀)P(C₆H₂Bu ^t ₃)

(3,4-diphenylcyclobut-3-ene-1,3-ylidene) bis(2,4,6-tri-t-butylphenyl)phosphine

(C₆H₄NM_e2-2)₂P(CH₂)₂P(C₆H₄NMe₂-2)₂

1,2-bis(bis(bis(2-dimethylaminophenyl)phosphine))

(C₆H₅NO)₂PN(Me)N(Me)P(C₆H₅NO)₂ ^*

(bis(bis(6-methylpyridin-2-yl)oxy)phosphino)-1,2-dimethyhydrazine

(η²-C₆H₁₂)P(CH₂)₂P(η2-C₆H₁₂)-

1,1′-ethane-1,2-diylbis(3,5-dimethylphosholane)

(C₇H₇O)₂PN(Me)N(Me)P-

bis(1,2-bis(bis(2methoxyphenylphosphino)-(C₇H₇O)₂ 1,2-dimethylhydrazine))

(C₇H₉N₂)P₂(C₆H₄)P(C₇H₉N₂)₂

N,N′,N″,N‴-(1,2-phenylene-bis(phosphinetriyl-P) bis(methylene))-tetrakis(N-methylpyridin-2-amine)

C₁₆H₁₆P₂

1,1′-diphenyl-3,3′,4,4′-tetramethyl-2,2´-biphosphole

(η²-C₂₀H₁₂O₂)PN(Me)N(Me)-C₂₀H₁₂O₂)

N,N′-bis(dinaphtho(2,1-d:1′,2′-f) (1,3,2)dioxa phosphein P(η²)2-yl)-1,2-dimethylhydrazine

(η²-C₂₈H₁₆O₂)O(CH₂)₂O(η²C₂₈H₁₆O₂)

1,2-bis(9,9′-biphenanthrolyl-phosphonito)ethane

(Me)(Bu ^t )P(C₈H₄N₂)P(Bu ^t )(Me)

2,3-bis(t-butyl(methyl)phosphino)quinoxaline

(Ph)(Cl)P(C₂H₁B₁₀)P(Cl)(Ph)

1,2-bis(chloro(phenyl)phosphino)-1,2-dicarba-closo-dodecarborane

(PhO)₂N(Me)N(Me)P(OPh)₂

bis(1,2-bis(diphenylphosphito)-1,2-dimethylhydrazine)

(PhO)₂P(C₅H₈)PPh₂

1,2-bis(bis(phenoxy)phosphino)cyclopentane

Ph₂CH(CN)PPh₂

bis(diphenylphosphino)acetonitrile

Ph₂P(C₁₀H₁₁O)PPh

6-(diphenylphosphino)-8,9dimethyl-10-phenyl-3-oxa-10-phosphatricyclo[5.2.1.0^2,6]deca-4,8-diene

Ph₂P(C₁₀H₁₃O₂)PPh

6-(diphenylphosphino)-8,9dimethyl-10-phenyl-3-oxa-10-phosphatricyclo[5.2.1.0^2,6]dec-8-en-4-ol

Ph₂P(C₁₀H₁₅O)PPh

5,6-dimethyl-7-phenyl-2-(diphenylphosphino)-7-phosphabicyclo(2.2.1)hept-5-en-2-yl)ethanol

Ph₂P(C₂₀H₁₀O₃)PPh₂

2-((9-anthracenyl)methylene)-4,5-bis(diphenyl-posphino)-4-cyclopenten-1,3-dione

Ph₂P(C₂₂H₁₀O₂)PPh₂

4,5-bis(diphenylphosphino)-2-(pyren-1-ylmethylene) cyclopent-4-ene-1,3-dione

Ph₂P(C₃H₃N₃)PEt ₂

4-(diisopropylphosphino)-5-diphenylphosphino-2-methyl-2H-1,2,3-triazole

Ph₂P(C₄H₈Ph₂)PPh₂

1,2-bis(diphenylphosphanyl)-3,4-diphenylcyclobutane

Ph₂P(C₅H₂O₂)PPh₂

4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-diene

Ph₂P(C₆H₄)P(η²-C₆H₁₂)

1-(2,5-dimethylhospholano)-2-(diphenylphosphino)-1,2-phenylene

Bu ^t ₂P(C₇H₆)PBu ^t ₂

(di-t-butyl(2-di-t-butyl phosphino)benzyl) phosphine

Bu ^t ₂P(C₇H₆)P(η²-C₁₀H₁₄O₃)

8-(2-((di-t-butylphosphino)methyl)phenyl)-1,3,5,7-tetramethyl-2,4,6-trioxa-8-phosphatricyclo [3.3.1.1^3,7]decane

(η²-C₄H₈)P(CH₂)₃P(η²-C₄H₈)

1,1′-(1,3-propanediyl)bisphospholane

(η²-C₅H₁₀)P(CH₂)₃P(η²-C₅H₁₀)

1,1′-(1,3-propanediyl)bisphosphinane

(η²-C₁₀H₁₀)P(CH₂)₃P((η²-C₁₀H₁₂)

1,1′-(1,3-propanediyl)bisphosphenane

(C₁₂H₄F₁₃)₂P(CH₂)₃P(C₁₂H₄F₁₃)₂

propane-1,3-diylbis(bis(4-(tridecafluorohexyl) phenyl)phosphine)

MesP(CH₂N(C₈H₅O₄)CH₂)₂PMes

3,7-(1,5-bis(3,5-dicarboxylphenyl)-3,7-bis(mesityl)-1,5-diaza-3,7-diphosphacyclooctane)

Ph₂P((CH₂SCH₂)PPh₂

(sulfanediylbis(methylene))bis(diphenylphosphine)

Ph₂P(C₁₀H₆)PPh₂

naphtalene-1,8-diylbis(diphenylphosphine)

Ph₂P(C₅H₅)PPh₂

bis(diphenylphosphino)pentane-2,4-diyl

Ph₂P(C₅H₈O)PPh₂

bis(diphenylphosphino)-2-ethyl-3-oxapropane

Ph₂P(C₅H₈O₂)PPh₂

2,2-bis(diphenylphosphinomethyl)propionic acid

Ph₂P(C₅H₉N)PPh₂

1-diphenylphosphino-2-(diphenylphosphinomethyl) pyrrolidine

Ph₂P(C₅H₉PPh₂)PPh₂

1,1,1-tris(diphenylphosphinomethyl)ethane

Ph₂P(C₆H₄)PPh₂

bis(diphenylphosphino)cyclohexyl

Ph₂P(C₆H₆O)PPh₂

3,5-bis(diphenylphosphino)-7-oxabicyclo[2.2.1]hept-2-ene

Ph₂P(C₇H₆N₄)PPh₂

(diphenylphosphino(5-(diphenylphosphino)pyrazolyl) pyrazolyl)methane

Ph₂P(CH₂)₃P(η²-C₆H₁₂)

1-((2′R,5′R)-2′,5′-dimethylphospholano)-3-(diphenylphosphino)propane

Ph₂P(CH₂CH(CH₂OH)O)PPh₂

3-(diphenylphosphanyl)-2-(diphenylphosphonito) propanol

(Ph₂PCH₂)(Ph)P(CH₂)₃P(Ph)

P,P′-bis(diphenylphosphinomethyl)-P,P′-(CH₂PPh₂)-diphenylpropane-1,3-diphospine

Ph₂P(CH₂N(C₄H₈SePh)CH₂)PPh₂

N,N-bis((diphenylphosphino)methyl)-N-(4-(phenylseleno)butyl)amine

Ph₂P(CH₂N(C₇H₇O)CH₂)PPh₂

N,N-bis(diphenylphosphino)methyl-4-methoxyaniline

Ph₂P(CH₂N(Ph)CH₂)P(η²C₁₀H₁₆O₃)

1,3,5,7-tetramethyl-6-(N-(diphenylphosphanyl-methyl)-N-(phenyl)aminomethyl)-2,4,8-trioxa-6-sphaadamantane

Ph₂P(CH₂N(Ph)CH₂)PPh₂

(N,N-bis(diphenylphosphino)methyl)aniline

Ph₂P(CH₂Si(Me)₂CH₂)PPh₂

2,2-dimethyl-1,3-bis(diphenylphosphino)-2-silapropane

Ph₂P(N(Me)C(═O)N(Me))PPh₂

N,N′-dimethyl-N,N′-bis(diphenylphosphino)urea

Pri₂P(C₁₂H₈)P(H)(Ph)

(diisopropyl(6-phenylphosphino)-1,2-dihydroacenaphthylen-5-yl) phosphine

Ph₂P(C₆H₆O)P(CH═CH₂)(Ph)

4-(diphenylphosphino)-5-(ethenylphenyl)phosphino-7-oxabicyclo[2.2.1]hept-2-ene

Ph₂P(C₆H₈O)PPh₂

4,5-bis(diphenylphosphino)-7-oxbicyclo[2.2.1]heptane

Ph₂P(C₉H₁₃O)PPh₂

5,6-dimethyl-7-phenyl-2-(diphenylphosphino)-phosphabicyclo(2.2.1)hept-5-en-2-yl)methanol

Ph₂P(C₉H₆)PBu ^t ₂

(di-t-butyl(3-diphenylphosphino)-1H-inden-2-yl)phosphine

Ph₂P(CH₂)₂P(η²-C₆H₁₂)

1-(2′,5′-dimethylphospholano-2-(diphenylphosphino)) ethane

Ph₂P{C(COOMe)═C(COOMe)}PBu ^t ₂

1-(di-t-butylphosphino)-2-(diphenyl-phosphino)-1,2-bis(methoxycarbonyl)ethene

Ph₂P{CH═C(COOEt)}P(η²C₁₈H₂₀N₂

2-(1,3-bis(2,6-dimethylphenyl)-2,3-dihydro-1H-1,3,2-diazaphospho-2-yl)-3-(diphenylhosphino)acrylic acid etylester

Ph₂PCH(Me)CH(Me)PPh₂

bis(diphenylphosphino)butane

Ph₂PCH(Me)P(OH)(2,4,6Bu ^t ₃C₆H₃

1-hydroxy-2-methyl-2,3-diphenyl-1-(1,4,6-tri-t-butylphenyl)-1,3-diphosphapropane

Ph₂PN(C₁₀H₇)PPh₂

N-(diphenylphosphino)-N-1-naphthyl-P,P-diphenyl-phosphinous amide

Ph₂PN(C₆H₄CN-2)PPh₂

2-cyanophenyliminotetraphenyldiphosphane

Ph₂PN(C₆H₄COOMe-3)PPh₂

(3-methoxycarbonylphenyl)bis(diphenylphosphino)amine

Ph₂PN(C₆H₄Et-2)PPh₂

N,N-bis(diphenylphosphino-2-ethylaniline

Ph₂PN(C₆H₄Ph-2)PPh₂

N,N-bis(diphenylphosphino-2-phenylaniline

Ph₂PN(CH₂C₄H₃O)PPh₂

N-(diphenylphosphino)-N-(2-furylmethyl)P,P-diphenyl-phosphinousamide

Ph₂PN(CH₂C₅H₄N)PPh₂

2-(bis(diphenylphosphino)aminomethyl)pyridine

Ph₂PN(CH₂CH═CH₂)PPh₂

bis(diphenylphosphino)(2-propenyl)amine

Ph₂PN(CH₂Et)PPh₂

N,N-bis(diphenylphosphino)propylamine

Ph₂PN(CH₂Ph)PPh₂

(benzylbis)(diphenylphosphino)amine

Ph₂PN{(CH₂)₂SCH₂Ph}PPh₂

(((2-benzylthio)ethyl)bisdiphenylphosphino)amine

Ph₂PN{C₆H₃(Me)₂-2,3}PPh₂

N,N-bis(diphenylphosphino)-2,3-dimethylaniline

Ph₂PN{CH(Me)(COOMe)}PPh₂

N,N-bis(diphenylphosphino)alaninemethylester

Ph₂PN{CH(Me)(Et)}PPh₂

N,N-bis(diphenylphosphanyl)-sec-butylamine

PhP(CH₂)(CH₂Si(CH₃)₂CH₂)PPh

5,5-dimethyl-1,3-diphenyl-1,3,5-diphosphasilinan-1,3-diyl

Pr ⁱ ₂P(C₂H₁₀B₁₀)PPr ⁱ ₂

1,2-bis(diisoropylphosphino)-1,2-dicarba-closo-dodecaborane

Pr ⁱ ₂P(o-C₆H₄)PPr ⁱ ₂

bis(diisopropylphosphino)o-phenylene

Pr ⁱ ₂P(OCH₂)P(η²-C₁₀H₁₆O₃)

((1,3,5,7-tetramethyl-2,4,6-trioxa-8-phosphatricyclo [3.3.1.1^3,7]dec-8-yl)methyl)di-isopropylphosphinite

(2-Pr ⁱ ₂C₆H₄)₂P(CH₂)P(2Pr ⁱ ₂C₆H₄)₂

bis(bis(2-isopropylphenyl)phosphino)methane

1 Introduction

The chemistry of platinum is an important area, particularly in the fields of biochemistry, catalysis, and theory. The chemistry of platinum coordination complexes has been extensively investigated over the last half century, especially the relationship between the structure and reactivity. The overwhelming majority of X-ray structural studies of square planar transition metal complexes are of platinum complexes. Although the most common oxidation state of platinum is +2, the metal is also found in 0, +1, +3, +4, +5, and non-integral oxidation states. Over 2,500 platinum complexes have been reviewed [1–5]. About 10% of these complexes exist as isomers and were summarized and analyzed [6], which include distortion (65%), cis-trans (30%), mixed isomers, and ligand isomerism.

Organophosphines are very attractive and useful ligands providing wide variability of stereochemistry in complexes with central transition metals, and platinum is no exception. Recently, we analyzed the structural parameters of organomonophosphines in monomeric PtP₂Cl₂ derivatives [7]. In this article, we classify and analyze structural characteristics of monomeric PtP₂Cl₂ complexes in which P-donor ligands are organodiphosphines. Organodiphosphines form a wide variety of n-membered metallocycles, from which organodisphosphines that form four-, five-, and six-membered metallocycles are analyzed in this article. The primary source of information was the Cambridge Crystallographic Database.

2 cis-PtP₂Cl₂ derivatives

There exist almost 130 monomeric Pt(ii) complexes with such chromophores for which structural parameters are available. In these derivatives, a square planar environment around each Pt(ii) atom is built up by homobidentate-P,P′ donor ligands together with a pair of chlorine atoms with different degrees of distortion.

2.2 Pt(η²-PCP)(Cl)₂ type

There are five complexes, mostly colorless, which crystallized in two crystal systems, orthorhombic (xl) and monoclinic (x4), and contain organodiphosphine ligands that form four-membered (PCP) metallocyclic rings. Such complexes are [Pt{η²-Bu ^t ₂PCH₂PBu ^t ₂}(C1)₂] [8], [Pt{η²-Ph₂PCH₂PPh₂}(C1)₂] [9], [Pt{η²-Ph₂PCH(CN)PPh₂}(Cl)₂]⸱2CH₂Cl₂ [10], [Pt{η²-(2-Pr ⁱ ₂C₆H₄)₂PCH₂P(2-Pr ⁱ ₂C₆H₄)₂}(C1)₂]·CH₂Cl₂ [11], and [Pt{η²-Ph₂PCH(Me)P(OH)(2,4,6-Bu ^t ₃C₆H₃)}(C1)₂]·EtOH·C₄H₈O [12]. The structure of [Pt{η²-Ph₂PCH(CN)PPh₂}(C1)₂] [10] is shown in Figure 1 as an example. The mean value of P–Pt–P bite angles is 74.4° (PCP). The mean values of the remaining L–Pt–L bond angles are 90.3° (Cl–Pt–C1), 96.6°, and 173.2° (P–Pt–C1). The mean values of Pt–L bond distances are 2.230 Å (P, trans to Cl) and 2.355 Å (C1, trans to P).

Figure 1

Structure of [Pt{η²-Ph₂PCH(CN)PPh₂}(Cl)₂] [10].

2.3 Pt(η²-PNP)(Cl)₂ type

There are 19 complexes, mostly pale yellow, which crystallized in three crystal systems: triclinic (xl), orthorhombic (x4), and monoclinic (x14), and contain chelating-P,P donor ligands build up four-membered (PNP) metallocycles. Such complexes are [Pt{(η²-Ph₂PN(Me)PPh₂}(C1)₂] [13], [Pt{(η²-Ph₂PN(CH₂E_t)PPh₂}(C1)₂ [14], [Pt{η²-Ph₂PN(CH₂CH═CH₂)PPh₂}(C1)₂] [15], [Pt{η²-Ph₂PN(CH₂Ph)PPh₂}(C1)₂]·CH₂Cl₂ and [Pt{(η²-Ph₂PN(CH₂C₅H₄N)PPh₂)}(C1)₂]·CH₂Cl₂ [16], [Pt{(η²-Ph₂PN{(CH₂)₂SCH₂Ph}PPh₂}(C1)₂] [17], [Pt{η²-Ph₂PN{CH(Me)(COOMe)}PPh₂}(C1)₂ [18], [Ptη²-Ph₂PN {CH(Me)(Et)}PPh₂}(Cl)₂] [19], [Pt{η²-Ph₂PN(C₆H₄CN-2)PPh₂}(Cl)₂] [20], [Pt{(η²-Ph₂PN(C₆H₄CN-3)PPh₂}(Cl)₂]·CH₂Cl₂, [Pt{(η²-Ph₂PN(C₆H₄CN-4)PPh₂}(C1)₂]·CH₂Cl₂, and [Pt{(η²-Ph₂PN(C₆H₄Ph-2)PPh₂}(Cl)₂]·CHCl₃ [21], [Pt{η²-Ph₂PN(C₆H₄Et₃)PPh₂}(Cl)₂]·CHCl₃ [22], [Pt{η²-Ph₂PN(C₆H₄Pr ⁱ -2)PPh₂}(Cl)₂]·Et₂O [23], [Pt{(η²-Ph₂PN(C₆H₄COOMe-3)PPh₂}(Cl)₂]·CHCl₃ [24], [Pt{η²-Ph₂PN{C₆H₃(Me)₂-2,3}PPh₂}(Cl)₂]·CHCl₃ and [Pt{η²-Ph₂PN{C₆H₃(Me)₂-2,5}PPh₂}(C1)₂] [25], [Pt{(η²-Ph₂PN(CH₂C₄H₃O)PPh₂}(C1)₂]·CH₂Cl₂ [26], and [Pt{η²-Ph₂PN(C₁₀H₇)PPh₂}(Cl)₂]·Me₂CO [27]. The structure of [Pt{(η²-Ph₂PN(CH₂Ph)PPh₂}(Cl)₂] [16] is shown in Figure 2 as an example. The mean value of P–Pt–P bite angles is 71.8° (PNP). The mean values of the remaining L–Pt–L angles are 92.2° (Cl–Pt–Cl), 97.5°, and 169.7° (P–Pt–Cl). The mean values of Pt–L bond distances are 2.210 Å (P, trans to Cl) and 2.354 Å (Cl, trans to P).

Figure 2

Structure of [Pt{(η²- Ph₂PN(CH₂Ph)PPh₂}(C1)₂] [16].

There are 24 examples of cis-Pt{η²-P(X)P}(Cl)₂ derivatives in which organodiphosphines create four-membered metallocyclic rings with the total mean value of P–Pt–P angles of 72.4° (for PNP and PCP in the cycle). The total mean values of the remaining L–Pt–L bond angles are 91.7° (Cl–Pt–Cl), 97.3°, and 170.4° (P–Pt–Cl). The total mean values of Pt–L bond distances are 2.214 Å (P) and 2.352 Å (Cl).

2.5 Pt(η²-PC-CP)(Cl)₂ type

There are 33 examples in which organodiphosphine ligands build up saturated five-membered metallocyclic rings (PC-CP): [Pt{η²-Et₂P(CH₂)₂Pet₂}(Cl)₂] [28], [Pt{η²-Bu ^t ₂P(CH₂)₂Pbu ^t ₂}(Cl)₂] (monoclinic, at 100 K) [29], and (monoclinic at 298 K) [Pt{η²-Bu ^t ₂P(CH₂)₂Pbut₂}(Cl)₂]PhCl [30], [Pt{η²-Ph₂P(CH₂)₂PPh₂}(Cl)₂ (monoclinic) [31], [Pt{η²-Ph₂P(CH₂)₂PPh₂}(Cl)₂]·CH₂Cl₂ [32], [Pt{η²-Ph₂P(CH₂)₂PPh₂}(C1)₂] (monoclinic) [33], [Pt{η²-Ph₂P(CH₂)₂PPh₂}(C1)₂] (monoclinic) [34], [Pt{η²-Ph₂P(CH₂)₂PPh₂}(Cl)₂] (orthorhombic, at 150 K) [35], [Pt{η²-cy₂P(CH₂)₂Pcy₂}(Cl)₂] [36], [Pt{η²-(Ph)(OH)P(CH₂)₂P(OH)(Ph)}(Cl)₂] [37], [Pt{η²-(C₆H₄Nme₂-2)₂P(CH₂)₂P(C₆H₄Nme₂-2}(Cl)₂]·CH₂Cl₂ [38], [Pt{η²-(C₆H₄Pr ⁱ -2)₂P(CH₂)₂P(C₆H₄Pr ⁱ -2)₂}(Cl)₂]·CH₂Cl₂ [39], [Pt{η²-Ph₂P(CH₂)₂P(η²-C₆H₁₂)}(Cl)₂] [40], [Pt{η²-(η²-C₆H₁₂)P(CH₂)₂P(η²-C₆H₁₂)}(Cl)₂] [41], [Pt{η²-(η²-C₂₈H₁₆O₂)P(CH₂)₂P(η²-C₂₈H₁₆O₂)}(Cl)₂]·CH₂Cl₂ [42], [Pt{η²-Ph₂PCH(Me)CH(Me)PPh₂}(Cl)₂] [43], [Pt{η²-Ph₂P(C₄H₄Ph₂)PPh₂)(Cl)₂] [44], [Pt{η²-(PhO)₂P(C₅-H₈)(Oph)₂}(Cl)₂] (monoclinic), [Pt(η²-(PhO)₂P(C₅H₈)(Oph)₂}(Cl)₂] (monoclinic) and [Pt{η²-(C₅H₁₀N)₂P(C₅H₈)P(C₅H₁₀N)₂}(Cl)₂] [45], [Pt{η²-Ph₂P(η³-C₉H₁₃O)PPh}(Cl)₂]·CH₂Cl₂ and [Pt{η²-Ph₂P(η³-C₁₀H₁₅O)PPh}(Cl)₂] [46], [Pt{η²-Ph₂P(η³- C₁₀H₁₁O)PPh}(Cl)₂] and [Pt{η²-Ph₂P(η³-C₁₀H₁₃O)PPh}(Cl)₂]·CHCl₃ [47], [Pt{η²-Ph₂P(C₆H₈O)PPh₂}(Cl)₂] [48], [Pt{η²-Ph₂P(C₆H₈O)Pet₂}(Cl)₂] and [Pt{η²-Ph₂P(C₆H₆O)P(CH═CH₂)(Ph)}(Cl)₂] [49], (Pt{η²-Ph₂P(C₃H₃N₃)Pet₂}(Cl)₂] [50], [Pt{η²-Pr ⁱ ₂P(C₂H₁₀B₁₀)PPr ⁱ ₂}(Cl)₂]·CH₂Cl₂ [51], [Pt{η²-(Ph)(Cl)P(C₂H₁₀B₁₀)P(Cl)(Ph)}(Cl)₂]·toluene, [Pt{η²-(C₂H₁₀B₁₀)P(Cl)(Net₂)}(Cl)₂]·toluene, and [Pt{η²-(Bu ^t )(Cl)P(C₂H₁₀B₁₀)P(Cl)(Bu ^t )}(Cl)₂] [52]. The structure of [Pt{η²-Ph₂P(CH₂)₂P(η²-C₆H₁₂)}(Cl)₂] [40] is shown in Figure 3 as an example. The mean value of P–Pt–P bite angles is 87.3° (PC-CP). The mean values of the remaining L–Pt–L bond angles are 82.2° (Cl–Pt–Cl), 92.5°, and 176.6° (P–Pt–Cl). The mean values of Pt–L bond distances are 2.225 Å (P, trans to Cl) and 2.362 Å (Cl, trans to P).

Figure 3

Structure of [Pt {η²Ph₂P(CH₂)₂P(η²-C₆H₁₂)}(Cl)₂] [40].

2.6 cis-Pt(η²-PC═CP)(Cl)₂ type

There are 15 examples in which organodiphosphine ligands create unsaturated five-membered metallocyclic rings (PC═CP). Such complexes are [Pt{η²-Ph₂P{C(COOMe)═C(COOMe)}PBu ^t ₂}(Cl)₂]·CHCl₃, [Pt{η²-Ph₂P{C(COOMe)═C(COOMe)}Pcy₂}(Cl)₂]·CH₂Cl₂ and [Pt{η²-cy₂P {C(COOMe)═C(COOMe)}Pcy₂}(Cl)₂]·CHCl₃ [53], [Pt{η²-Ph₂P(C₉H₃)PBu ^t ₂}(Cl)²] [54], [Pt{η²-Pr¹ ₂P(C₆H₄)PPr ⁱ ₂}(Cl)₂] [55], [Pt{η²-(C₇H₉N₂)₂P(C₆H₄)P(C₇H₉N₂)₂}(Cl)₂] [56], [Pt{η²-Ph₂P(C₆H₄)P(η²-C₆H₁₂)}(Cl)₂]·CH₂Cl₂ [57], [Pt{η²-(Bu ^t )(Me)P(C₈H₄N₂)P(Me)(Bu ^t )}(Cl)₂]. CH₂Cl₂ [58], [Pt{η²-Ph₂P(C₅H₂O₂)PPh₂}(Cl)₂] and [Pt{η²-Ph₂P(C₂₀H₁₀O₂)PPh₂}(Cl)₂]·CH₂Cl₂ [59], [Pt{η²-Ph₂P(C₂₂H₁₀O₂)PPh₂}(Cl)₂]·CH₂Cl₂ [60], [Pt{η²-Ph₂P{CH═C(COOEt)P(η²-C₁₈H₂₀N₂)}(Cl)₂]·C₆H₆ [61], [Pt{η²-C₁₆H₁₆P₂}(Cl)₂] [62], [Pt{η²-methyldiphos}(Cl)₂] [63], and [Pt{η²-(C₆H₂Bu ^t ₃)P(C₁₆H₁₀)P(C₆H₂Bu ^t ₃)}(Cl)₂]·Me₂CO [64]. The structure of [Pt{η²-cy₂P{C(COOMe)═C(COOMe)}Pcy₂}(Cl)₂] [53] is shown in Figure 4 as an example. The mean value of P–Pt–P bite angles is 86.5° (PC═CP). The mean values of the remaining L–Pt–L bond angles are 91.5° (Cl–PtCl), 90.8°, and 175.8° (P–Pt–C1). The mean values of Pt–L bond distances are 2.221 Å (P, trans to Cl) and 2.354 Å (Cl, trans to P).

Figure 4

Structure of [Pt{η²-cy₂P{C(COOMe)═C(COOMe)}Pcy₂}(Cl)₂] [53].

2.7 cis-Pt(η²-PNNP)(Cl)₂ type

There are 11 examples, mostly yellow, in which organodiphosphine donor ligands form five-membered metallocyclic rings of the (PNNP) type and together with a pair of chlorine atoms completed a distorted square planar environment around each Pt(ii) atom. Such complexes are [Pt{η²-(PhO)₂PN(Me)N(Me)P(OPh)₂}(Cl)₂] and [Pt{η²-(η²-C_l2H₁₀)PN(Me)(η²-C₁₂H₁₀)}(Cl)₂] [65], Pt{η²-(C₆H₅NO)₂PN(Me)N(Me)P(C₆H₅NO)₂}(Cl)₂] (orthorhombic and triclinic) [66], [Pt{η²-(Cl)₂PN(Me)N(Me)P(Cl)₂}(Cl)₂] [67], [Pt{η²-(η²-C₂₀H₁₂O₂)PN(Me)N(Me)P(η²-C₂₀H₁₂O₂)}(Cl)₂]⸱2H₂O [68], [Pt{η²-(PhO)₂PN(Et)N(Et)P(OPh)₂}(Cl)₂], [Pt{η²-(C₇H₇O)₂PN(Me)N(Me)P(C₇H₇O)₂}(Cl)₂]·CH₂Cl₂ and [Pt{η²-(C₇H₇O)₂}(Cl)₂]·CH₂Cl₂.H₂O [69], and [Pt{η²-Ph₂PN(Ph)N(Ph)PPh₂}(Cl)₂]·CHCl₃ [70]. The structure of [Pt{η²-Ph₂PN(Ph)N(Ph)PPh₂}(Cl)₂] [70] is shown in Figure 5 as an example. The mean value of P–Pt–P bite angles is 87.3° (PNNP). The mean values of the remaining L–Pt–L bond angles are 90.5° (Cl–Pt–Cl), 92.5°, and 176.0° (P–Pt–Cl). The mean values of Pt–L bond distances are 2.194 Å (P, trans to Cl) and 2.344 Å (Cl, trans to P).

Figure 5

Structure of [Pt{η²-Ph₂PN(Ph)N(Ph)PPh₂}(Cl)₂] [70].

2.8 cis-Pt(η²-PCOP)(Cl)₂ type

There are two triclinic examples: [Pt{η²-Pr ⁱ ₂P(OCH₂)P(η²-C₁₀H₁₆O₃)}(Cl)₂] and [Pt{η²-Ph₂P(OCH₂)P(η²-C₁₀H₁₆O₃)}(Cl)₂]·CHCl₃ [71] in which organodiphosphine donor ligands form five-membered metallocyclic rings of PCOP type. The structure of [Pt{η²-Pr ⁱ ₂P(OCH₂)P(η²-C₁₀H₁₆O₃)}(Cl)₂] [71] is shown in Figure 6 as an example. The mean value of the P–Pt–P bite angle is 84.0° (PCOP). The mean values of Pt–L bond distances are 2.22 A° (P, trans to CI) and 2.355 A° (Cl, trans to P). The mean values of the remaining L–Pt–L bond angles are 94.0° (CI–Pt–C1), 95.2°, and 175.0° (P–Pt–Cl).

Figure 6

Structure of [Pt{η²-Pr ⁱ ₂P(OCH₂)P(η²-C₁₀H₁₆O₃)}(Cl)₂] [71].

3 cis-Pt(η²-PXXXP)Cl₂ derivatives

There are over 40 examples in which each Pt(ii) atom has a square-planar environment with varying degrees of distortion, build up by organodiphosphine P,P′-donor ligands, and a pair of chlorine atoms. The homodiphosphine ligands create a wide variety of atoms between the P,P′- donor atoms. These varieties are PC₃P (24 examples), PCNCP (6 examples), PCSCP (1 example), PCSiCP (1 example), PNCNP (3 examples), POSiOP (1 example), POPNP (1 example), PC₂OP (1 example), and PC₂NP (1 example). There are 11 examples in which organodiphosphines create twin chelate rings of the type: P(CNC)₂P (3 examples) and P(CNC)(CCC)P (1 example).

3.1 cis-Pt(η²-PC₃P)(Cl)₂ type

There are 24 examples of this type, which crystallize in the three crystal systems: triclinic (3 examples), orthorhombic (8 examples), and monoclinic (13 examples).

Such complexes are [Pt{η²-Bu ^t ₂(CH₂)₃PBu ^t ₂}(Cl)₂]⸱0.5(PhCl) [72], [Pt{η²-Ph₂P(CH₂)₃PPh₂}(Cl)₂] [73], [Pt{η²-Ph₂P(CH₂)₃PPh₂}(Cl)₂]⸱0.5(C₆H₆) [74], [Pt{η²-Ph₂P(CH₂)₃PPh₂}(Cl)₂]·CH₂Cl₂ [75,76], [Pt{η²-cy₂P(CH₂)₃Pcy₂}(Cl)₂]⸱2CH₂Cl₂ [77], [Pt{η²-(η²-C₄H₈)P(CH₂)₃P(η² _-C₄H₈)}(Cl)₂]·CHCl₃; [Pt{η²-(η²-C₅H₁₀)P(CH₂)₃P(η²-C₅H₁₀)}(Cl)₂], and [Pt{η²-(η²-C₆H₁₂)P(CH₂)₃P(η²-C₆H₁₂)}(Cl)₂] [78], [Pt{η²-(C₁₂H₄F₁₃)₂P(CH₂)₃P(C₁₂H₄F₁₃)₂}(Cl)₂] [79], [Pt{η²-(Ph₂P(CH₂)(Ph)P(CH₂)₃P(Ph)(CH₂PPh₂)}(Cl)₂]·H₂O [80], [Pt{η²-Ph₂P(CH₂)₃P(η²-C₆H₁₂)}(Cl)₂] [40], [Pt{η²-Ph₂P(C₆H₄)PPh₂}(Cl)₂], and [Pt{η²-Ph₂P)(C₅H₈O)PPh₂}(Cl)₂] [81], [Pt{η²-Ph₂P(C₅H₅)PPh₂}(Cl)₂ [82], [Pt{η²-Ph₂P(C₅H₈O₂)PPh₂}(Cl)₂]Me₂SO [83], [Pt{η²-Ph₂P(C₆H₆O)PPh₂}(Cl)₂] [84], [Pt{η²-Ph₂P(C₁₀H₆)PPh₂}(Cl)₂]·CH₂Cl₂ [85], [Pt{η²-(Ph)(Bu ^t )P(C₁₀H₆)P(Bu ^t )(Ph)}(Cl)₂]·CH₂Cl₂ and [Pt{η²-(C₆F₅)(Me)P(C₁₀H₆)P(Me)(C₆F₅)}(Cl)₂]·CH₂Cl₂ [86], [Pt{η²-Bu ^t ₂P(C₇H₆)PBu ^t ₂(Cl)₂]·CH₂Cl₂ and [Pt{η²-Bu ^t ₂P(C₇H₆)P(η²-C₁₀H₁₄O₃)}(Cl)₂]·CH₂Cl₂ [87], [Pt{η²-Pr ⁱ ₂P(C₁₂H₈)P(H)(Ph)}(Cl)₂] [88], [Pt{η²-Ph₂P(C₆H₂F₆O)PPh₂}(Cl)₂] [89], and [Pt{η²-Ph₂P(C₅H₉PPh₂)PPh₂}(Cl)₂] [90]. The structure of [Pt{η²-Bu ^t ₂P(C₇H₆)PBu ^t ₂(Cl)₂]·CH₂Cl₂ [87] is shown in Figure 7 as an example. The mean value of the P–Pt–P bite angle is 94.6° (PC₃P).

Figure 7

Structure of [Pt{η²-Bu ^t ₂P(C₇H₆)PBu ^t ₂(Cl)₂] [87].

3.2 cis-Pt(η²-PCXCP)(Cl)₂(X = N, S, or Si) type

There are six examples of the cis-Pt(η²-PCNCP)(Cl)₂ type. These complexes crystallized in three crystal systems: orthorhombic (one example), triclinic (one example), and monoclinic (four examples). Such complexes are [Pt{η²-Ph₂P(CH₂N(Ph)CH₂)PPh₂}(Cl)₂]·CHCl₃ [91], [Pt{η²-Ph₂P(CH₂N(C₇H₇O)CH₂)PPh₂}(Cl)₂]·CH₂Cl₂ [92], [Pt{η²-Ph₂P(CH₂N(Ph)CH₂)P(η²-C₁₀H₁₆O₃)}(Cl)₂]·CHCl₃ and [Pt{η²-Ph₂P(CH₂N(p-tolyl)CH₂)P(η²-C₁₀H₁₆O₃)}(Cl)₂]·CHCl₃⸱Et₂O [93], [Pt{η²-Ph₂P(CH₂N(C₄H₈SePh)CH₂)PPh₂}(Cl)₂] [94], and [Pt{η²-Ph₂P(C₇H₆N₄)PPh₂}(Cl)₂]·CH₂Cl₂ [95]. The structure of [Pt{η²-Ph₂P(CH₂N(C₇H₇O)CH₂)PPh₂}(Cl)₂]·CH₂Cl₂ [92] is shown in Figure 8 as an example. The mean value of the P–Pt–P bite angle is 94.0° (PCNCP).

Figure 8

Structure of [Pt{η²-Ph₂P(CH₂N(C₇H₇O)CH₂)PPh₂}(Cl)₂] [92].

Monoclinic [Pt{η²-Ph₂P(CH₂SCH₂)PPh₂}(Cl)₂] [91] is the only example in which homobidentate –P,P donor ligand creates six-membered metallocyclic ring of the PCSCP type (95.8°).

Orthorhombic [Pt{η²-Ph₂P(CH₂Si(Me)₂CH₂)PPh₂}(Cl)₂] [96] is also the only example of the PCSiCP metallocyclic ring (96.8°).

3.3 cis-Pt(η²-PNCNP)(Cl)₂ type

There are three examples: monoclinic [Pt{η²-Ph₂P(N(Me)C(═O)N(Me)PPh₂}(Cl)₂], triclinic [Pt{η²-Ph₂P(N(Et))C(═O)N(Et))PPh₂}(Cl)₂] [97], and orthorhombic [Pt{η²-Ph₂P(N(Me)C(═O)N(Me)PPh₂}(Cl)₂]·CHCl₃ [98] in which the chelating –P,P′ donor ligands create six-membered metallocyclic rings of the PNCNP type. The structure of [Pt{η²-Ph₂P(N(Me)C(═O)N(Me)PPh₂}(Cl)₂] [97] is shown in Figure 9 as an example. The mean value of the P–Pt–P bite angle is 94.0° (PNCNP).

Figure 9

Structure of [Pt{η²-Ph₂P(N(Me)C(═O)N(Me)PPh₂}(Cl)₂] [97].

3.7 cis-Pt{η²-P(XXX)₂P}(Cl)₂ type

There are four examples in which the chelating –P,P′ donor ligands create a pair of six-membered metallocyclic rings. In monoclinic [Pt{η²-PhP(CH₂N(Ph)CH₂)₂PPh}(Cl)₂] [104] and in two triclinic [Pt{η²-PhP(CH₂N(C₈H₅O)CH₂)₂PPh}(Cl)₂] [105] and [Pt{η²-Ph₂P(CH₂N(C₈H₅O₄)CH₂)₂PMes}(Cl)₂]·dmf [106], the respective chelating -P,P′ donor ligands create a pair of P(CNC)₂P type with the mean P–Pt–P bite angle of 84.2°.

The structure of monoclinic [Pt{η²-PhP{CH₂N(C₈H₅O₄)CH₂}(CH₂CH₂CH₂)PPh}(Cl)₂]·Me₂SO [106] is shown in Figure 10. (Me₂SO) was omitted. As can be seen, the chelating –P,P′ donor ligand creates a pair of the six-membered rings of P(CNC)(CCC)P type. The values of the P–Pt–P bite angles are 84.5° (CNC) and 85° (CCC), respectively.

Figure 10

Structure of [Pt{η²-PhP{CH₂N(C₈H₅O₄)CH₂}(CH₂CH₂CH₂)PPh}(Cl)₂] [106].

4 Conclusions

This article covers 127 examples of cis-Pt{η²–P(X) _n P}(Cl)₂ (n = 1,2,3) complexes, in which each Pt(ii) atom is in a distorted square planar environment built up by homodidentate P,P′ donors of organodiphosphines and a pair of chlorine atoms. These complexes crystallized in four crystal classes: tetragonal (2 examples), orthorhombic (23 examples), triclinic (35 examples), and monoclinic (67 examples). The organodiphosphines create four-, five-, and six-membered metallocyclic rings. The four-membered metallocyclic are two types: PCP and PNP; the five-membered are four types PC–CP, PC═CP, PNNP, and PCOP. The six-membered are 11 types: PC₃P, PCNCP, PCSCP, PCSiCP, PNCNP, PCCOP, PCCNP, POCNP, POSiOP, P(CNC)₂P, and PCNCCCCP. The P–Pt–P bite angles opening (total mean values) in the order: 72.4°(PXP) < 86.4°(PXXP) < 94.0°(PXXXP).

The mean value of the Pt–P bond distance of 2.217 Å (P, trans to Cl) is stronger (more covalent) than the Pt–Cl bond distance of 2.364 Å (Cl, trans to P) as a reason for much stronger trans-influence of P over Cl atom.

There are two types of isomerism: ligand and distortion. The following seven complexes: [Pt{η²-Ph₂P{N(C₆H₄CN-2)}-PPh₂}(Cl)₂] [20], [Pt{η²-Ph₂P{N(C₆H₄CN-3)}PPh₂}(Cl)₂], and [Pt{η²-Ph₂P{N(C₆H₄CN-4)}PPh2}(Cl)₂] [21], [Pt{η²-Ph₂P{N(C₆H₃(Me)₂-2,3)}PPh₂}(Cl)₂ ] and [Pt{η²-Ph₂P{N(C₆H₃Me₂-2,5}PPh₂}(Cl)₂] [25]; [Pt{η²-(C₆H₆NO)₂P{N(Me)N(Me)}P(C₆H₆NO)₂}Cl₂] and [Pt{η²-(C₆H₆NO^*)₂P{N(Me)N(Me)}P(C₆H₆NO^*)₂}Cl₂] [66]. Each Pt(ii) atom has a square-planar geometry with differing degrees of distortion. The sum of four Pt–P(x₂) + Pt–Cl(x₂) bond distances reflects the position of respective group and increases in the orders: 9.097 Å(…CN-2) [20] < 9.106 Å (…CN-4) < 9.144 Å (…CN-3) [21], 9.136 Å (…2,3) < 9.156 Å (…2,5) [25], and 9.030 Å (L*) < 9.053 Å (L) [66].

The coexistence of two or more species differing only by the degree of distortion of the M–L bond and L–M–L bond angles is typical of the general class of distortion isomers [6]. There are two complexes: [Pt{η²-PhO)₂P(R,R-C₅H₈)P(OPh)₂}Cl₂] and [Pt{η²-(PhO)₂P(S,S-C₅H₈)P(OPh)₂}Cl₂] [45] which contain two crystallographic independent molecules within the same crystal with the sum of four Pt–L bond distances: 9.084 and 9.100 Å for (R,R-C₅H₈); and 9.086 and 9.096 Å for (S,S-C₅H₈). These two complexes are ligands as well as distortion isomers.

Three monoclinic Pt{η²-Bu ^t ₂P(CH₂)₂PBu ^t ₂}Cl₂ with the values of four Pt–L bond distances: 9.238 Å [29], 9.254, and 9.268 Å [30] are somewhat longer than in another three monoclinic [Pt{η²-Ph₂P(CH₂)₂PPh₂}Cl₂] 9.144 Å [33], 9.166 Å [34], and 9.168 Å [35]. The mean values of Pt–P and Pt–Cl bond distances are 2.259 and 2.308 Å in the former and 2.217 and 2.363 Å in the latter.

These data indicate that the group plays a nonpliant role, alkyl (Bu ^t ) vs aryl (Ph). It can be proposed the aryl (Ph) group reduced trans-influence of the P atom over the alkyl group (Bu ^t ). Finally, there are another four complexes: triclinic Pt{η²-Ph₂P(CH₂)₃PPh₂}Cl₂ [73], monoclinic Pt{η²-Ph₂P(Cl₂)₃PPh₂}Cl₂ [74], orthorhombic Pt{η²-Ph₂P(CH₂)₃PPh₂}Cl₂ [75], and orthorhombic Pt{η²-Ph₂P(CH₂)₃PPh₂}Cl₂ [76]. The mean Pt–P and Pt–Cl bond distances are 2.232 and 2.371 Å. Pt{η²-(C₆H₅NO)₂PN(Me)N(Me)P(C₆H₅NO)₂}(Cl)₂] and [Pt{η²-(C₆H₅NO)₂PN(Me)N(Me)P(C₆H₅NO₂*)₂(Cl)₂] [65] are classical examples of ligand isomerism.

There is a cooperative effect between the structural parameters of the complexes with four- and five-membered metallocyclic rings. When the P–Pt–P bite angle opens, the cis-Cl–Pt–Cl and cis-P–Pt–Cl bond angles close with the total mean values, which opens in the orders: 72.4° (PXP) < 91.7° (Cl–Pt–Cl) < 97.3° (P–Pt–Cl) vs 86.9° (PXXP) < 88.0° (Cl–Pt–Cl) < 92.7° (P–Pt–Cl). In general, complexes with four-membered metallocycles are more distorted than those with five-membered metallocycles, as expected.

This article also includes over 40 cis-PtP₂Cl₂ derivatives in which the chelating –P,P′ donor ligands create six-membered metallocyclic rings. There is a wide variety of the respective chelate rings of the types: PC₃P (most common), PCNCP, PCSCP, PCSiCP, PNCNP, PCCOP, PCCNP, POPNP, POSiOP, and P(XXX)₂P. The total mean values of Pt–P and Pt–Cl bond distances are 2.222 and 2.358 Å. The total mean values of cis-L–P–L bond angles are 94.0° (P–Pt–P), 87.6° (Cl–P–Cl), and 89.0° (P–Pt–Cl), and the total mean value of the trans-P–Pt–Cl bond angle is 175.3°.

There are two examples [91,100] that contain two crystallographically independent molecules within the same crystal, differ mostly by degree of distortion, and are examples of distortion isomerism [6].

There are cooperative effects between the selected structural parameters in the complexes with four-, five-, and six-membered metallocyclic rings (Table 1). As can be seen, white P–Pt–P bite angles open with the size of the respective metallocyclic ring, and the cis-Cl–Pt–Cl and P–Pt–Cl bond angles close in the same order. Both Pt–P and Pt–Cl bond distances smoothly elongate with the size of the respective chelate rings.

The analysis and classification of structural parameters of Pt{η²-P(X) _n P}Cl₂ (n = 4, 5, 6, 7, 8, 10, 11, 15, 18) complexes are in progress, and such structural set (subject of our subsequent paper, being in preparation) will be discussed and compared with Pt{η²-P(X) _n P}Cl₂ (n = 1, 2, 3) (this study).

During the collection and organization of the data, it has become evident that despite the increasing availability of data retrieval systems, the tracking of relevant structural data is not always simple. Poorly chosen keywords for indexes appear to be one problem that results in the effective invisibility of some material from a structural point of view. Some original papers lack important information such as atomic coordinates and analysis of intermolecular distances. Increasingly, such data are also being relegated to supplementary material. In view of those limitations, we believe that such a review such as this can continue to serve useful function by centralizing available material and delimiting areas worthy of further investigation.