Transition metal complexes containing P(C 6H 5)(C 6H 4Cl-2) 2. The effect of added Lewis bases as a probe for substitution reactions occurring in ambient temperature Suzuki couplings catalyzed by Pd/P(C 6H 5)(C 6H 4Cl-2) 2

Abstract

The reactivity of the d 8 transition metal complexes, [NiBr 2(CH 3OCH 2CH 2OCH 3)] and MCl 2L 2 (M=Pd, Pt; L=CH 3CN; L 2=1,5-cyclooctadiene), towards P(C 6H 5)(C 6H 4Cl-2) 2 ( 1) was investigated. While treatment of [PdCl 2(cod)] with 2 equiv of 1 resulted in displacement of the weakly coordinating cyclooctadiene and formation of [PdCl 2(P(C 6H 5)(C 6H 4Cl-2) 2) 2], analogous reactions with [PtCl 2(cod)] afforded the monosubstituted species [PtCl 2(cod)(P(C 6H 5)(C 6H 4Cl-2) 2)]. The disubstituted complex [PtCl 2(P(C 6H 5)(C 6H 4Cl-2) 2) 2] was successfully obtained by treatment of [PtCl 2(NCCH 3) 2] with 2 equiv of 1. However, attempts to react 1 with [NiBr 2(CH 3OCH 2CH 2OCH 3)] were unsuccessful. The chlorinated triphenyl phosphine is quite labile and is readily displaced from [PdCl 2(P(C 6H 5)(C 6H 4Cl-2) 2) 2] by various Lewis bases including nitrogen containing ligands such as 2,2′-bipyridine. The molecular structure of trans-[PdCl 2(P(C 6H 5)(C 6H 4Cl-2) 2) 2] was determined by X-ray diffraction and represents the first molecular structure determination of a transition metal complex containing 1. This complex crystallizes in the monoclinic space group P2 1/ n with a=10.3928(3) Å, b=16.0102(4) Å, c=13.1884(4) Å, β=90.714(2)°, and Z=4. Key geometric parameters include PdCl(1) =2.309(1) Å, PdP(1)=2.334(1) Å; PdP(1)C(7)=118.3(2)°, PdP(1)C(1)=115.3(2)°, C(1)C(6)Cl(2)=120.7(4)° and Cl(1)PdP(1)=85.86(4)°.