Reactions of [(η6-arene)RuCl2]2with Aromatic Phosphines Containing Methoxy Groups in 2,6-Positions

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Abstract
Reactions of [(η6-arene)RuCl2]21 (arene = p-cymene (a), 1,2,3,4-Me4C6H2 (b), 1,2,3-Me3C6H2 (c)) with tris(2,6-dimethoxyphenyl)phosphine (TDMPP) led to loss of two molecules of CH3Cl to give (η6-arene)Ru[{2-O-C6H3-6-OMe}2{C6H3(OMe)2-2,6}], 2a−c, which contains a trihapto ligand (η3-P,O,O) derived from TDMPP, whereas the 1,3,5-Me3C6H3 (1d), 1,2,3,5-Me4C6H2 (1e), and C6Me6 (1f) complexes did not react with TDMPP. The structures of 2a and 2b were confirmed by X-ray analyses: for 2a, a = 11.691(2) Å, b = 15.228(2) Å, c = 10.320(1) Å, α = 95.93(1)°, β = 113.783(9)°, γ = 83.86(1)°, triclinic, P1̄, Z = 2, R = 0.051; for 2b, a = 17.79(2) Å, b = 15.43(1) Å, c = 20.93(1) Å, β = 91.25(8)°, monoclinic, P21/n, Z = 8, R = 0.056. Bis(2,6-dimethoxyphenyl)phenylphosphine (BDMPP) reacted with 1a, 1b, and 1d at room temperature to give (η6-arene)RuCl[PPh(2-O-C6H3-6-OMe){C6H3(OMe)2-2,6}], 3a,b,d, which contains a dihapto (η2-P,O) ligand derived from BDMPP by an X-ray analysis of 3a: a = 12.33(1) Å, b = 14.246(8) Å, c = 11.236(9) Å, α = 91.47(8)°, β = 117.28(6)°, γ = 111.70(6)°, triclinic, P1̄, Z = 2, R = 0.040. A similar reaction with 1f recovered the starting materials, but that in refluxing MeCN produced [(η6-C6Me6)Ru[PPh(2-O-C6H3-6-OMe}2], 4f, containing a trihapto (η3-P,O,O) ligand derived from BDMPP. Complex 1d reacted with BDMPP at reflux in MeCN/CH2Cl2 and resulted in a loss of an arene ring to give a five-coordinate complex, Ru[η2-P,O-PPh(2-O-C6H3-6-OMe){C6H3(OMe)2-2,6}]2(MeCN), 5. Treatment of (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) with 1f gave (η6-C6Me6)RuCl[η2-P,O-PPh2(2-O-C6H3-6-OMe)], 6f, and that with 1b gave (η6-1,2,3,4-Me4C6H2)RuCl[η2-P,O-PPh2(2-O-C6H3-6-OMe}], 6b, and (η6-1,2,3,4-Me4C6H2)RuCl2[η1-P-PPh2{C6H3(OMe)2-2,6}], 7b. The phosphine ligand of 6b acted as a bidentate ligand derived from MDMPP: a = 8.074(4) Å, b = 16.816(3) Å, c = 18.916(4) Å, β = 94.05(3)°, monoclinic, P21/n, Z = 4, R = 0.051. Transformation of 7b to 6b readily occurred accompanying an elimination of MeCl. Reaction of 1a with MDMPP eliminated an arene ring to give the octahedral compound RuCl2[η2-P,OMe-PPh2{C6H3(MeO)2-2,6}]2, 8. An X-ray analysis of 8 showed that two MDMPP ligands were in a cis-position: a = 10.596(14) Å, b = 27.586(12) Å, c = 13.036(8) Å, β = 108.17(7)°, monoclinic, P21/n, Z = 4, R = 0.035.

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