Diphenyl(phenylethynyl)phosphine d6 [Rh(III), Ir(III), Ru(II)] complexes:: Preparation of homo (μ-Cl)2 and hetero (μ-Cl) (μ-PPh2C=CPh) bridged d6-d8 compounds

The novel P-coordinated diphenyl(phenylethynyl)phosphine complexes [Cp*MCl2(PPh(2)CdropCPh)] [M = Rh 1, Ir 2] have been prepared by the bridge splitting of [Cp*MCl2](2) With PPh(2)CdropCPh. Treatment of 1 and 2 with AgTfO and PPh(2)CdropCPh affords the corresponding cationic compounds [Cp*MCl(PPh(2)CdropCPh)(2)](OTf) [M = Rh 3, Ir 4, OTf = triflate], respectively. The analogous neutral Ru(II) derivative [Cp*RuCl(PPh(2)CdropCPh)(2)] 5 has been obtained by reaction of PPh(2)CdropCPh and the binuclear complex [Cp*RuCl2](2) in the presence of Zn as the reductor. The molecular structures of 1 and 3-5 have been determined by single-crystal X-ray diffraction. The alkynyl fragments in cations 3 and 4 and in the neutral ruthenium derivative 6 are eclipsed, but the C-alpha...C-alpha interligand distances are longer than the minimal separation necessary (3.2-3.4 Angstrom) to promote alkynyl coupling: The reactivity of these mono (1, 2) and bis[diphenyl(phenylethynyl)phosphine] (3-5) complexes toward [cis-Pt(C6F5)(2)(THF)(2)] has been explored. Treatment of 1 with 1 equiv of [cis-Pt(C6F5)(2)(THF)(2)] in CH2Cl2 affords the doubly chloride bridged [(PPh(2)CdropCPh)Cp*Rh (mu-Cl)(2)Pt(C6F5)(2)] 6. In contrast, the analogous iridium derivative [Cp*IrCl2(PPh(2)CdropCPh)] 2 reacts with [cis-Pt(C6F5)(2)(THF)(2)], leading to a mixture of isomers [(PPh(2)CdropCPh)Cp*Ir(mu-Cl)(2)Pt(C6F5)(2)] 7a and [Cp*ClIr(mu-Cl)(mu-kP:eta(2)-PPh(2)CdropCPh)Pt(C6F5)(2)] 7b (7a/7b approximate to 2.5:1). Similar cationic [(PPh(2)CdropCPh)Cp*M(mu-Cl)(mu-kP:eta(2)-PPh(2)CdropCPh)Pt(CcF5) (OTf) [M = Rh 8, Ir 9] and neutral [(PPh(2)CdropCPh)Cp*Ru(mu-Cl)(mu-kP:eta(2)-PPh(2)CdropCPh)Pt(C6F5)(2) ] 10 hetero-bridged complexes are formed by treatment of the bis[diphenyl(phenylethynyl)]phosphine (3-5) complexes with [cis-Pt(C6F5)(2)(THF)(2)] in CH2Cl2. The structure of 10 has been confirmed by a single-crystal X-ray diffraction analysis.