Stereodynamics of metal butylphenylphosphine chloro {trans-[(tert-Bu)2PPh]2MCl2 [M = platinum(II) and palladium(II)]} and metal butylphenylphosphine chloro carbonyl {trans-[(tert-Bu)2PPh]2M(CO)Cl [M = rhodium(I) and iridium(I)]}: dynamic NMR and x-ray crystallographic studies